Two different types of carcinoid tumors of the lung: immunohistochemical and ultrastructural investigation and their histogenetic consideration.

Carcinoid tumors have been an interesting clinical and pathological entity for pathologists because of their unique histopathologic pattern of "Zellballen" (cell ball) and the hormones they produce demonstrable by histochemical and biochemical methods, including immunohistochemistry, and the presence of cytoplasmic dense-core particles demonstrable by electron microscopy. Since carcinoid tumors were established as an entity more than a century ago by Oberndorfer, who was credited with coining the term "carcinoid," meaning carcinoma-like tumors, tumors presenting with similar characteristics have been reported in most of parenchymal organs, including lungs. Carcinoid tumors in the lungs usually occur as bronchocentric tumors and present with typical histopathologic characteristics of carcinoid tumors, but they may present with significant variation in their cellular compositions, in contrast to the midgut carcinoid tumors. In the latter, tumor cells are quite similar to enterochromaffin granule containing crypt cells, which are regarded as their progenitor cells. Currently, a similar histogenetic explanation is applied to all carcinoid tumors occurring elsewhere. The bronchus is one of the most common anatomic sites in which the carcinoid tumors occur. However, bronchial carcinoid tumors differ from the midgut counterparts in microscopic appearance, showing more variability in cellular shape and composition from the classical form of midgut carcinoid tumors. In the lungs, neuroendocrine cells (NEC) are normally found in two different ways. Firstly, they are found as randomly scattered single cells (Kultchitsky cells) similar to enteric counterparts, and, secondly, they are found in aggregates known as "neuroepithelial bodies" (NEB) usually found in the branching point of bronchi. Interestingly, they keep a close anatomic relationship with parasympathetic nerve structures and even form synapses. NEB are usually found in the early stage of fetal development and are claimed to play an important role in the branching of bronchi and regeneration of bronchial epithelial cells following tissue injury. They are claimed to play an important function as a chemoreceptor apparatus related to oxygen tension of the breathing air. To test the hypothesis that histopathologic variability found in bronchial carcinoids may be related to the fact that lungs are endowed with more than one type of NEC, the author reviewed 36 cases of bronchial carcinoids and found 8 cases in which tumor cells varied significantly from typical carcinoids in cell shape and arrangement. Tumor cells tend to be spindly with frequent presence of S-100-positive sustentacular cells. The latter was designated as type II carcinoid and the rest as type I. Ultrastructurally, tumor cells in type I exhibited features more typical for epithelial cells. The tumor cells were usually polygonal, forming closely packed cell masses, and cell membranes were closely apposed with frequent primitive cell junctions. The membrane-bound dense-core granules were of variable size and appearance and larger than those seen in type II in which the size of granules ranged from 160 to 350 nm. In 2 cases of type I, frequent cells contained myelin bodies similar to those found in type II alveolar cells. In 14 cases of type I tumors, tumor cells formed lumens into which microvilli were converging. In 5 cases, some areas showed increased cell size exceeding the usual limit of pathologist's comfortable range of small cells. In 2 cases, the tumor contained areas of adenocarcinoma. Tumor cells in type II were rather oblong and closely packed without any intercellular spaces and the majority of tumor cells contained dense-core granules typical for so-called P granules. These cells seem to give out slender cell processes containing a few dense-core granules. In rare foci, groups of thin cell processes aggregate where profiles of processes cut at different angles can be seen. In such areas one can recognize the profiles of microtubules in many of them. In one tumor, which was previously reported by the author (Ultrapath 2001;25:207), microtubule-containing dendrites were common, as seen esthesioneuroblastomas. They appeared similar to dendrites of neurons. In addition to these chief cells, there were variable numbers of agranulated cells usually found at the periphery of cell balls bordering the interstitium. Some of these cells contained large aggregates of polymorphic dense bodies. However, no definite premelanosomes were found in our series. The results indicate that there exist at least two different types of carcinoid tumors in the lungs and their immunohistochemical and ultrastructural characteristics are quite different. The type I tumors are quite similar to those found in the midgut and their histogenesis might be similar. The type II tumors showed rather definite neural features in their immunophenotypic and ultrastructural characteristics, which is difficult to explain by the same histogenesis applied to type I. We postulate that type II tumors have a different histogenesis from type I. They may derive from NEC of neuroepithelial bodies rather than Kultchitsky cells. In this regard, it is interesting to note the similarity between neuroepithelial bodies of the lungs and olfactory bulbs in their cellular composition and anatomic arrangement of epithelial cells and nerves, and the similarity between tumors they produce, bronchial carcinoid tumors in our type II and olfactory neuroblastomas. It is concluded that there are two types of bronchial carcinoid tumors having two different histogenetic pathways. Detailed analysis of the ultrastructural characteristics is the best and definite means to differentiate two types of pulmonary carcinoid tumors.

Gastrointestinal stromal tumor: an ultrastructural investigation on regional differences with considerations on their histogenesis.

Gastrointestinal stromal tumor (GIST) is the most frequent spindle cell tumor in the gastrointestinal tract and may arise from esophagus to rectum. The stomach is the most frequent site, followed by small intestine, rectum, and esophagus. There have been some regional differences reported in their histopathologic and clinical presentations. The purpose of this study is to compare ultrastructural features of GIST, according to its anatomic site, in order to provide additional data to support the current concept of its histogenesis. Fifty-four GISTs (27 from stomach, 23 from small intestine, and 4 from rectum) were included in the study. Histopathologically, gastric GISTs tended to be more frequently epithelioid, particularly those in children, while small intestinal GISTs (SISTs) were mostly spindly in all but three cases. All four of the rectal GISTs were spindly. Ultrastructurally, there seem to be considerable regional differences. In the majority of gastric GISTs, in both epithelioid and spindle types, tumor cells exhibited focal features of myoid differentiation evidenced by the presence of incomplete external lamina (EL) and/or focal accumulations of thin fibers with interrupted electron densities consistent with actin filaments. However, features of myoid differentiation were exceptional for SISTs and rectal GISTs, being present in only one example in each. Some gastric GISTs, particularly those having an epithelioid appearance, showed cell borders luxuriously decorated by long filopods (anemone cell features). Anemone cell features were also present in spindle cell types of gastric GISTs as well as SISTs, albeit it was simpler and less luxuriant. Skeinoid fibers were present in the majority of SISTs and rectal GISTs, but absent in all gastric GISTs except one. These differences appeared to be too significant to propose a uniform histogenesis for all GISTs. Nevertheless, on closer analysis, certain features could be identified to explain a line of differentiation in all GISTs ranging from (1) polygonal uncommitted epithelioid mesenchymal cells with cell borders decorated by luxuriant fimbria, to (2) spindly tumor cells with less prominent fimbria, or (3) cells with or without features of minimum myoid differentiation characterized by the focal presence of cytoplasmic actin fibers or incomplete EL or skeinoid fibers, which might represent an altered product of EL protein. These findings led the author to speculate that the probable primordial cells of GIST may be the primitive mesenchymal cells, which have the potential to differentiate into myoid cells. In this regard, it is important to note that the putative primordial cell of GIST, interstitial cells of Cajal (ICC), and intestinal smooth muscle cells have been shown to develop from the common progenitor cells of the primitive gut, and c-Kit plays a crucial role in the determination of their fate to differentiate to muscle cells or ICC. The author concludes that all GISTs derive from stem cells in the gut retaining some of the differentiation potential seen in primitive gut cells. One of the likely candidates for such cells in the intestinal musculature is ICC-DMP (interstitial cells of Cajal associated with deep muscular plexus) identified as ICC having smooth muscle features identified exclusively by electron microscopy. These cells have been shown to have some of the features of muscle cells by the presence of external lamina and less well-organized cytoplasmic filaments; they also express CD117 in the cytoplasm. Furthermore, recent studies demonstrated the presence of so-called progenitor cells of ICC, similar to ICC-DMP in appearance, expressing insulin-like growth factor and CD34, indicating their stem cell nature. The author proposes that all GISTs develop from the common progenitor cells similar to primitive gut cells, which may differentiate into tumor cells with more myoid features in the stomach (similar to so-called ICC-DMP) as well as spindle cells with less myoid features (similar to ICC-MP [interstitial cells of Cajal associated with the myenteric plexus] in the small intestine and rectum). ICC-DMP have been recruited in the group of ICC by electron microscopic technique alone without methylene blue stain and it is questionable whether they are part of ICC depicted by the ICC network originally shown by Dr. Cajal more than century ago. Recent discovery of their expression of insulin-like growth factors may indicate that they represent persisting primitive gut cells (gut stem cells), which may serve as the progenitor cells to GIST. It is also pointed out that in this era of ICC and GIST pandemonium, a minority of intestinal stromal tumors with mature smooth muscle features have been totally ignored; these now appear to belong to GISTs, representing the best differentiated example among the tumors developing from the same progenitor cells.

CDX-2 homeobox gene expression in human gastric carcinoma and precursor lesions.

BACKGROUND: Recent studies have demonstrated that CDX-2 is expressed in the intestinal metaplasia of the stomach and intestinal-type gastric cancer. To address the role of CDX-2 in carcinogenesis of gastric carcinomas of intestinal type, the expression of CDX-2 in gastric carcinoma and precursor lesions were examined using immunohistochemistry. METHODS: A total of 160 specimens diagnosed as gastric carcinomas or non-invasive neoplasia from 158 patients were analyzed for CDX-2 expression by immunochemical methods. Patients were classified into histopathologic subgroups according to the Padova international classification: 60 cases of low-grade non-invasive neoplasia, 55 cases of high grade, and 45 cases of invasive intestinal-type adenocarcinoma. The CDX-2 expression in non-neoplastic gastric mucosa including intestinal metaplasia was also evaluated in the areas included in the histologic sections. RESULTS: The CDX-2 expression was localized in the epithelial cell nuclei in the area of intestinal metaplasia with or without dysplasia and carcinoma, consistent with its role as a transcriptional regulator. No CDX-2 reactivity was noted in the normal mucosa in all cases. The CDX-2 expression was detected in 73.3% of low-grade cases, 85.5% of high-grade cases and 91.1% of intestinal-type adenocarcinoma cases. In the gastric mucosa with intestinal metaplasia, 89.7% of the samples were positive. The CDX-2-expressing cells in intestinal metaplasia were more prevalent than in dysplasia and carcinoma. Expression of CDX-2 showed a statistically significant positive correlation with increasing grade of dysplasia and carcinoma. CONCLUSIONS: These findings suggest that CDX-2 expression in stomach cancer may be a marker of the progression of gastric carcinogenesis, and that its activation may represent an early event.

Expression of PTEN in the progression of cervical neoplasia and its relation to tumor behavior and angiogenesis in invasive squamous cell carcinoma.

BACKGROUND AND OBJECTIVES: Loss of PTEN expression has been associated with tumor progression and adverse patient outcome. The purpose of this study was to evaluate PTEN expression in the successive steps of progression in cervical neoplasia and to determine its correlation with tumor angiogenesis and clinicopathologic features in squamous cell carcinoma of the uterine cervix. METHODS: Immunohistochemical staining with anti-PTEN antibody was performed in a total of 160 patients with 12 normal cervical epithelium, 63 cervical intraepithelial neoplasia (33 CIN I, 30 CIN III), and 85 cervical squamous cell carcinomas. Microvessels were immunohistochemically labeled with an antibody for CD34. Computerized image analysis was used to evaluate microvessel density (MVD). RESULTS: Reduced PTEN expression progressively increased along the continuum from normal epithelium to squamous cell carcinoma (P < 0.01). There was no significant correlation between PTEN expression and MVD. On univariate analysis, stage and reduced PTEN expression were significant prognostic factors for both disease-free and overall survival. However, stage was the only independent prognostic factor by multivariate analysis. CONCLUSIONS: Our results suggest that tumor progression in the cervical epithelium is accompanied by loss of PTEN protein expression. Reduced PTEN expression is not associated with tumor angiogenesis of squamous cell carcinoma of the uterine cervix.

Ossifying fibromyxoid tumor: modified myoepithelial cell tumor? Report of three cases with immunohistochemical and electron microscopic studies.

Ossifying fibromyxoid tumors (OFMT) are rare soft tissue tumors of uncertain histogenesis and clinical behavior. Since Enzinger, Weiss, and Liang first described 59 examples in 1989 (Am Surg Pathol. 13:817-827), approximately 150 cases have been reported. Their clinicopathologic features are fairly well characterized and their histogenesis remains unknown. Three examples of soft tissue tumors with typical histopathologic characteristics of OFMT were studied: case 1, a 43-year-old female with a 2.5-cm tumor of the back; case 2, a 56-year-old man with an 8-cm thigh mass; and case 3, an 81-year-old female with a 13.5-cm buttock tumor. For immunohistochemistry, formalin-fixed, paraffin-embedded tissue sections were stained with antibodies against cytokeratin, smooth muscle actin, desmin, vimentin, S-100 protein, EMA, and collagen type IV using standard ABC-peroxidase methods. For electron microscopy, tissue samples fixed in EM-grade buffered formalin were processed according to routine methods. Immunohistochemistry showed that the tumor cells were positive for vimentin and S-100 protein in all 3 cases. Stains for collagen type IV revealed diffusely positive staining in the stroma with a tendency for stronger staining around the cell borders in 2 out of 3 cases. Desmin was positive in one and actin was positive in one other case. By electron microscopy, tumor cells were characterized by centrally located round to oval nuclei with varying amounts of cytoplasm containing scanty cytoplasmic organelles. There were rare profiles of rough-surfaced endoplasmic reticulum (RER) and rare mitochondria with areas of condensed intermediate filaments. No tonofilaments or actin filaments were present. There were multiple short web-like processes, some of which were attached to that of neighboring cells by primitive cell junctions. In all 3 cases, lesional cells showed external lamina (EL), which was abundant in case 1, forming redundant scrolls frequently. In case 2, EL was less prominent and incomplete, and interrupted portions of EL were present only along the periphery of cell columns or nests bordering the stroma. In case 3, which behaved as a malignant tumor, the tumor cells were less differentiated spindle cells with primitive cellular features, and EL was rarely found along the short span of tumor cell borders. In this study, tumor cells in OFMT were polygonal to stellate often with multiple short cytoplasmic processes. The tumor cells were found to form cell clusters attached by primitive intercellular junctions between cytoplasmic processes forming intercellular bridges. The cell borders facing the stroma around cell clusters tended to be flat and had incomplete EL, while no EL was present along the cell borders facing the inner aspect of cell clusters. These ultrastructural findings together with immunophenotypic expression of S-100 protein presented closer resemblance to those of modified myoepithelial cells in pleomorphic adenomas of salivary glands and skin appendages rather than peripheral nerve sheath tumors. The authors conclude that these findings render more support to the hypothesis of myoepithelial histogenesis of OFMT. They also conclude that ultrastructural study not only helps accurate diagnosis, but also may aid in predicting malignant behavior by the degree of deviation from the typical examples of OFMT.

Expression of PTEN in ovarian epithelial tumors and its relation to tumor behavior and growth.

OBJECTIVE: To evaluate the expression of tumor suppressor gene phosphatase and tensin homologue on chromosome 10 (PTEN) in ovarian epithelial tumors and its correlation with tumor growth and clinicopathologic features in ovarian adenocarcinomas. STUDY DESIGN: Immunohistochemical staining with anti-PTEN antibody was performed in 54 adenocarcinomas and 23 borderline tumors of the ovary. The apoptotic cells were visualized by terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling, and proliferative cells were visualized by staining with Ki-67 antibody. RESULTS: Reduced PTEN expression was significantly higher among the adenocarcinomas than the borderline tumors (p < 0.001). Reduced PTEN expression in adenocarcinomas did not correlate with International Federation of Obstetrics and Gynecology (FIGO) stage. The Ki-67 index (KI) and apoptotic index were significantly higher in adenocarcinomas as compared with borderline tumors (p < 0.001). Tumors with reduced PTEN expression in ovarian adenocarcinomas had a significantly higher KI than those with normal PTEN expression (p < 0.01). By univariate analysis, FIGO stage and histologic type correlated with survival. However, FIGO stage was the only independent prognostic factor by multivariate analysis. CONCLUSION: Our results suggest that alteration of the PTEN gene may be associated with malignant transformation of ovarian epithelial tumors. The PTEN gene seems to be a negative regulator of cell proliferation in ovarian adenocarcinomas.

Stromal elements for tumor diagnosis: a brief review of diagnostic electron microscopic features.

Tumor diagnosis mainly depends on the appearance of the tumor cells in recapitulating the appearance of primordial cells from which they arise. However, certain tumors may present with specific stromal changes that may assist/enhance the diagnosis. In this presentation, diagnostic stromal features have been reviewed. The cytoplasm is enclosed by a unit membrane, which serves as a barrier to, as well as an interface with, surrounding structures. Epithelial cells usually show characteristic basal-apical orientation. In mesenchymal tissue, different types of interface can be found in different types of mesenchymal tissue. External lamina can be defined as an anatomic structure, which encloses anatomic functional units. In epithelial tissue, cells in a functional unit are enclosed within a well-defined external lamina (EL). In malignant epithelial tumors, EL can become increasingly indistinct as tumors become less differentiated, and one has to look for it diligently. Within the external lamina, epithelial cells are closely packed with closely apposed cell membranes and cell attachment junctions. In contrast to epithelial tissue, mesenchymal tissue is usually characterized by the stromal elements they produce. Individual cells are embedded in the stroma, and individual mesenchymal cells represent the functional unit. Vascular endothelial cells are an exception since their relationship to stroma resembles to that of epithelial cells. Thus, tumors deriving from mesenchymal cells known to have external lamina such as muscle cells and Schwann cells tend to show total enclosure of cells by external lamina. In malignant muscle tumors, external lamina production can be focally present and found only by diligent search. In Schwann cell tumors, the presence of EL is prominent in low-grade tumors and more irregular and variable in malignant tumors. In the latter, stromal aggregation of scrolls of external lamina can be characteristic. Similar features are seen in ossifying fibromyxoid tumors. Fibronexus junctions (composed of extracellular fibronectin fillements linking intracellular 5-nm filaments) is claimed to be typical of myofbroblasts. Finding them in spindle cell tumors justifies a diagnosis of myofibroblastomas. There have been several stromal changes diagnostic for certain tumors found only by electron microscopy. Fibrous long-spaced collagen (known as Luse bodies) is diagnostic for peripheral nerve sheath tumors, but they can rarely be found in other tumors. Luse bodies usually appear as focally as crystallized aggregates apart from the regular collagenous interstitial stroma. They should be distinguished from other nonspecific long-spaced collagen changes. The changes are diffusely stromal in contrast to Luse bodies. Spiny collagen and amianthoid fibers are interesting collagen fibrils and their diagnostic value is questionable. Skeinoid fibers (SF) are short-spaced collagen of 41- to 45-nm banding so-named because of their peculiar appearance by electron microscopy simulating skeins of yarn. They were originally described in neurogenic tumors and small intestinal stromal tumors with features of gastrointestinal autonomic nerve tumors (GANT). Although there have been a few sporadic case reports of the presence of skeinoid fibers in nonneurogenic tumors, the frequent presence of SF in spindle cell tumors signifies their neurogenic nature in this authors' experience. An exception to this is that SF can be a constant element of rare ciliary body tumors known as ciliary mesectodermal leiomyomas, in which tumor cells show some resemblance to smooth muscle as well as Schwann cells. In addition to SF, several other types of peculiar crystallized collagen were observed in GANT tumors, particularly those with multiple tumor syndromes such as neurofibromatosis and Carney's triad. They simulate the appearance of railroad tracks or centrosomes. The reason for this is not known. The authors speculate that such collagen crystallization may be caused by genetic alterations involving collagenosis. Further studies will be necessary to clarify their pathogenesis. Another peculiar stromal change is electron-dense stromal filamentous aggregates with extra-long banding of > 250-nm periodicity previously described in Ewing sarcomas. This stromal change simulating a tiger skin pattern is also seen in primitive neuroectodermal tumors and malignant melanomas. In view of continually new discoveries of stromal changes that can be used for the differential diagnosis of tumors, the importance of close evaluation of stromal elements of tumors, and diligent application of electron microscopy in tumor diagnosis cannot be overemphasized.

Expression of cyclooxygenase-2 in adenocarcinomas of the uterine cervix and its relation to angiogenesis and tumor growth.

OBJECTIVE: The purpose of this study was to evaluate cyclooxygenase (COX)-2 expression in adenocarcinomas of the uterine cervix and its correlation with clinicopathologic features, angiogenesis, and tumor growth. METHODS: Thirty-nine cases of FIGO clinical stage I and II adenocarcinoma of the uterine cervix were examined by immunohistochemical studies with anti-COX-2. Microvessels were immunohistochemically labeled with an antibody to CD34. Computerized image analysis was used to evaluate microvessel density (MVD). The apoptotic cells were visualized by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) and proliferative cells were visualized by staining with Ki-67 antibody. RESULTS: Twenty-eight tumors (71.8%) were classified as COX-2 positive. COX-2 expression correlated with FIGO stage (P < 0.01). Tumors expressing COX-2 had a significantly higher MVD and Ki-67 index than those that did not express COX-2 (P < 0.05). However, COX-2 expression did not correlate with the apoptotic index. In univariate long-rank analysis, COX-2 expression, MVD, and FIGO stage were associated with shortened survival. However, FIGO stage and MVD were the only independent prognostic factors by multivariate analysis. CONCLUSIONS: Our results suggest that COX-2 expression in cervical adenocarcinomas may contribute to tumor progression by increasing angiogenesis and cell proliferation.

Reduced PTEN expression is associated with poor outcome and angiogenesis in invasive ductal carcinoma of the breast.

Loss of PTEN expression has been associated with advanced stages of tumor. Tumor angiogenesis is involved in tumor progression. In breast cancer, a high frequency of mutations of the PTEN locus has been reported. However, the prognostic importance of PTEN expression and its correlation with angiogenesis in breast cancer have not been well established. Formalin-fixed, paraffin-embedded tissues from 99 women with a primary diagnosis of invasive ductal carcinoma were evaluated for PTEN expression by immunohistochemical methods. The microvessel density (MVD) was also studied by immunohistochemical labeling of endothelial cells with CD34 antibody. Computerized image analysis was used to evaluate MVD. Reduced PTEN expression was seen in 27.3% of invasive ductal carcinoma. The MVD ranged from 22.0 to 197.0, with a median value of 58.5 (65.4 +/- 27.9). Reduced PTEN expression correlated with lymph node status (P < 0.01), tumor grade (P < 0.05), and tumor-node-metastasis (TNM) stage (P < 0.05). There was a statistically significant correlation between reduced PTEN expression and increased MVD (P < 0.05). The mean MVD was higher in reduced PTEN-expressive tumors, irrespective of stage, compared with normal PTEN-expressive tumors with the same stage. On multivariate analysis, only TNM stage and reduced PTEN expression correlated with survival. Our results suggest that reduced PTEN expression may be an independent prognostic indicator in patients with invasive ductal carcinoma. PTEN loss may be associated with increased tumor angiogenesis.

A comparison of modified MonoPrep2 of liquid-based cytology with ThinPrep Pap test.

OBJECTIVE: The purpose of this study is to evaluate a modified MonoPrep2 (MP) of liquid-based cytology (LBC) to search for a less expensive alternative technique usable for screening of cervical cancers. STUDY DESIGN: Cervicovaginal direct-to-vial samples from 1218 consecutive patients were processed with the modified MP technique and the results were compared with those of currently popular ThinPrep Pap test (TP) technique. RESULTS: Both MP and TP methods provide uniformly spread thin layers of cells without cellular overlap or significant obscuring elements. The diameter of the circular area was 20 mm in MP and 22 mm in TP. Obscuring factors were slightly more frequent in MP but not enough to affect interpretation. Thirteen specimens were excluded from the study because of poor specimen quality in MP. In 1205 patients, there was an absolute agreement in results (the Bethesda diagnosis system) between the two methods, and discordances were observed in only 18 (1.5%) in 1187 cases (98.5%). Furthermore, there was no significant difference in diagnostic accuracy in histopathologic correlation between the two methods. The sensitivity of MP was slightly lower than that of TP, and the specificity of MP was higher than that of TP. A human papillomavirus (HPV) test with polymerase chain reaction (PCR) using broad-spectrum probes has yielded good results in both MP and TP samples. CONCLUSIONS: The modification of the MP method gave comparable results to those of TP in terms of smear quality, cytologic diagnostic evaluation, and biopsy correlation with much less cost. The modified MP offers a cost-effective alternative to the currently popular expensive techniques of liquid-based cytology practical for cervical cancer screening.

Metaplastic mammary carcinoma with osteoclast-like giant cells: identical point mutation of p53 gene only identified in both the intraductal and sarcomatous components.

Metaplastic mammary carcinoma with osteoclast-like giant cells is a rare neoplasm, and the histogenesis of this tumor remains controversial. A case of metaplastic mammary carcinoma with osteoclast-like giant cells in a 72-year-old woman is reported with p53 mutational analysis. Microscopically, the tumor was composed of a dominant sarcomatous stromal component containing osteoclast-like giant cells and a minor component of intraductal carcinoma. Immunostaining for p53 revealed strong positivity in both intraductal and sarcomatous components, but not in osteoclast-like giant cells. Mutational analysis of the p53 gene disclosed an identical point mutation in both intraductal and sarcomatous components, but not in osteoclast-like giant cells, indicating that both components share the same progenitor cells, and osteoclast-like giant cells represent a reactive infiltrate.

Correlation between cyclooxygenase-2 and tumor angiogenesis in non-small cell lung cancer.

The role of COX-2 expression and angiogenesis of lung cancer is yet to be delineated. Eighty four non-small cell lung cancer (NSCLC) specimens were evaluated for COX-2 expression, microvessel density (MVD), and vascular endothelial growth factor (VEGF) expression by immunohistochemical methods. The relationships between COX-2 expression and MVD, VEGF expression, and survival time were analyzed. COX-2 expression was observed in the cytoplasm and membrane of the carcinoma cells, and premalignant cells. COX-2 was positive in 67 cases (79.8%). There was a statistically significant correlation between COX-2 expression and tumor size, TNM stage, tumor type, VEGF expression, and vascular pattern with survival in univariate analysis. No significant correlation was seen between COX-2, VEGF expression and MVD. A lack of expression of either COX-2 or VEGF expression or both, however, was associated with lower MVD than the group with both expressed. The difference was statistically significant (P=0.005). Statistically significant differences were also observed according to TNM stage, vascular pattern, COX-2 expression, and VEGF expression. With multivariate analysis, only TNM stage and COX-2 expression retained their significance as independent predictors of survival. COX-2 expression takes part in tumor angiogenesis and is a significant poor prognostic factor in the surgically resected NSCLC. COX-2 inhibitor, either in combination therapy with other agents, or for chemoprevention, may be effective via suppression of angiogenesis in this fatal disease.

Intestitial cells of Cajal in the human small intestine: immunochemical and ultrastructural study.

The stem cell kinase CD117 has recently been found to play an important role in the development of interstitial cells of Cajal (ICC), which are currently regarded as pacemaker cells of the gastrointestinal tract. CD117 is expressed in both gastrointestinal stromal tumors (GIST) and ICC, with the latter regarded by many as the progenitor cells of GIST. The authors investigated immunoreactivity of 25 normal surgically removed small intestinal tissues and correlated the findings with electron microscopy (EM) on 12 cases. In all cases CD117-positive cells were frequently seen around the myenteric plexi either singly or in groups. CD117-positive cells on immunostained sections corresponded to the cells appearing as fibroblast-like or undifferentiated primitive mesenchymal cells around the myenteric ganglia and interstitial spaces by EM. In contrast, S-100 stain revealed a fine network of positive staining throughout the muscularis. Branches of nonmyelinated axons and nerve endings were found regularly between myocytes with direct contact with muscle cells by EM. The cells that we could depict as ICC because of their distribution and staining pattern of CD117 were limited to the nonmuscular mesenchymal cells. No muscle cell-like ICC were found. Instead, the muscle cells in direct contact with nerve endings were often disfigured and the cytoarchitectural contents for muscle cells became less distinct because of lighter staining and loss of definite focal densities among actin filaments. However, these latter cells did maintain most muscle cell features, such as continuous external lamina, caveolae, and some of the peripheral densities. These findings raise a possibility that previous investigators could have included these altered muscle cells into the ICC group. It was also found that intestinal muscularis not only was richly endowed with an elaborate neural network of delicate axonal extensions and dense-core granule containing nerve endings traversing through and between myocytes, but also showed frequent synapse-like direct contact between nerve endings and muscle cells. These findings indicate that enteric nerves may play a major role in the control of intestinal motility, while CD117-positive cells play an accessory role as cells of Cajal as originally speculated. Further studies are necessary to better define and characterize interstitial cells of Cajal, which will be useful in the correlation of the vast number of data concerning the possible role of CD117-positive ICC in the pacemaker function of the intestine and oncogenesis of GIST.

Bednar tumor: report of a case with immunohistochemical and ultrastructural study.

A slowly growing tumor in the right shoulder of a 38-year-old white male, which felt like a superficial cystic mass, was studied. The spindle cells, which represented the main component of the tumor, were arranged in a typical storiform pattern and were positive for CD34 and focally for CD117. The pigmented cells were mostly found at the center of the storiform whorls and were negative for S-100 protein and HMB-45. Ultrastructurally, the tumor consisted predominantly of nondescript mesenchymal spindle cells that resembled fibroblasts. The tumor cells blended into a loosely arranged stromal tissue background. The general appearance of pigmented cells was very similar to the nonpigmented spindle cells. The pigment appeared to be a mature form of melanin granules. The lack of premelanosomes, cell injections, basal lamina, and pinocytotic vesicles was inconsistent with a neural origin/neural differentiation hypothesis for this tumor.

Postirradiation epithelioid angiosarcoma of the breast: a case report with immunohistochemical and electron microscopic study.

A case of postirradiation epithelioid angiosarcoma of the breast in a 72-year-old woman is reported. She had had right breast conserving surgery, axillary lymph node dissection, and 50 Gy external beam radiation therapy for infiltrating ductal carcinoma. A skin lesion on the irradiated breast appeared 5 years after completion of radiation. Angiosarcoma was diagnosed in a contralateral axillary mass 8 months later. Light microscopically, the tumor was characterized by a sheet-like growth of epithelioid cells with focal vasoformative areas. Tumor cells were reactive for factor VIII-related antigen, cytokeratin and CD34. Electron microscopically, the tumor cells were round with smooth cell borders. They were closely apposed, occasionally forming a small lumen containing single red blood cells or aggregates of platelets. Groups of tumor cells were enclosed by an external lamina. The tumor cells had abundant cytoplasm with sparse organelles. Rare suggestive Weibel-Palade bodies were present. The immunohistochemical and ultrastructural findings in this postirradiation tumor were in agreement with previously reported findings in non-irradiation-induced epithelioid angiosarcomas.

Peculiar cytoplasmic inclusions in oncocytic adrenal cortical tumors: an electron microscopic observation.

Two cases of an oncocytic adrenal cortical tumor that contained peculiar cytoplasmic crystalline inclusions in the tumor cells are presented. The patients were 49- and 72-year-old females without clinical and biochemical evidence of adrenal cortical or medullary dysfunction. The adrenal tumors weighed 80 and 200 g each. These crystalline inclusions were present in groups of longitudinal profiles or clusters of crossly cut aggregates. They appeared in clusters of membrane-bound columns. On longitudinal sections, they appeared as rigid rods of homogenous density measuring 36 nm in width, but when they were cut transversely their paracrystalline nature became apparent. They were composed of closely packed microtubules in rectangular blocks. The microtubules measured 12.5 nm with a hollow center measuring 4.2 nm. The inclusions were within the membrane-bound cisterna of rough-surfaced endoplasmic reticulum. The significance of these inclusions is not clearly understood; however, they have been seen only in adrenal cortical tumors and their presence may be helpful in the differential diagnosis of adrenal oncocytic tumors. One patient presented with a tumor in which gross and microscopic appearance was compatible with a pheochromocytoma. This case exhibited an oncocytic appearance and pronounced cellular pleomorphism. Ultrastructural studies were necessary to recognize the tumor cells as cortical cells. The tumor cells contained abundant mitochondria with tubular cristae, paranuclear parallel stacks of granular endoplasmic reticulum, and relatively prominent smooth endoplasmic reticulum. These features are typical of adrenocortical cells. In addition, frequent tumor cells contained the peculiar cytoplasmic inclusions herein described.

Comparative evaluation of angiogenesis in gastric adenocarcinoma by nestin and CD34.

Tumor angiogenesis has been shown to be important for growth and metastasis in human neoplasms. Angiogenesis is usually determined by immunohistochemical staining of tumor tissue using various antibodies specific for endothelial cells. CD34 has been the one most commonly used in studies of tumor angiogenesis. Nestin, a class VI intermediate filament protein, was reported to be a good angiogenic marker in animal models. The aim of the current study was to compare the predictive value of angiogenesis as determined by CD34 and nestin on the same group of patients with advanced gastric carcinomas and to evaluate the possibility of nestin being a newer, better angiogenesis marker. Immunohistochemical staining using antinestin polyclonal antibody and anti-CD34 monoclonal antibody was carried out on surgical specimens from 61 patients with advanced gastric adenocarcinomas. The sensitivity of each of the two antibodies was evaluated by microvessel density (MVD) measurement by counting vessels in three 200x fields of intense neovascularization ("hot spots") of invasive tumors using a digital image analyzer. Immunoreactivity for nestin and CD34 was seen in the endothelial cells, and no stain was noted in the negative controls. MVD determined by nestin [87.74 +/- 29.30 (mean +/- standard deviation)] staining was significantly greater than that obtained by CD34 (82.48 +/- 32.27), and the difference was statistically significant. There was no correlation between MVD and patient clinical outcome with either antibody. Interestingly, in patients with larger carcinomas, MVD determined by nestin correlated better with longer survival than CD34. The difference was statistically significant. These results indicate that nestin is the better marker to evaluate neovascularity in endothelial cells. Evaluation of MVD determined by immunohistochemistry has limited value in patients with gastric carcinomas.