Resection of an obstructive neonatal cardiac myxoma of the infundibulum.

Myxoma, the most common primary cardiac tumor in adults, is rare in neonates. We describe a myxoma arising from the infundibulum of the right ventricle causing significant outflow tract obstruction in an otherwise normal newborn. Serial echocardiograms revealed an increasing gradient across the right ventricular outflow tract prompting surgery. The patient underwent successful excision of the myxoma with an uneventful recovery.

A clinicopathologic and immunohistochemical study of 35 anaplastic carcinomas of the pancreas with a review of the literature.

Anaplastic pancreatic carcinomas are rare tumors, frequently displaying a variety of growth patterns. The literature lacks a comprehensive study of this tumor. Thirty-five cases of anaplastic carcinoma of the pancreas diagnosed between 1955 and 1997 were retrieved from the Endocrine Registry at the Armed Forces Institute of Pathology. Histology, immunophenotype, molecular analysis, and patient follow-up were analyzed. The tumors of 10 women and 25 men, aged 34 to 85 years (mean age at presentation, 62.5 years), were studied. Patients had vague symptoms (weight loss, pain, and fatigue, nausea, or vomiting), lasting an average of 13.2 weeks. The tumors, of an average size of 9.2 cm, were usually in the head or tail of the pancreas. The tumors were widely infiltrative, histomorphologically separated into predominantly large, pleomorphic cell, or spindle cell groups. Tumor phagocytosis and necrosis were noted. Immunohistochemical studies confirmed an epithelial origin with at least one epithelial marker in 78% of the tumors. K-ras mutations by sequence analysis were found in eight of 12 cases tested. Surgical biopsy/excision was used in all patients. Twenty-nine of 35 patients died of disease (average, 5.2 months), three died with no evidence of disease (average, 56.9 months), and three patients were alive at last follow-up (average, 94.0 months), one with residual disease. There was no statistically significant difference in survival between patients with and without a K-ras mutation. Anaplastic carcinoma of the pancreas usually occurs in the head of the pancreas in older men. The epithelial nature of the pleomorphic cells (giant or spindled) can usually be documented. Patients with K-ras mutations have a shorter survival time, even though the overall prognosis for all anaplastic carcinomas is fatal (93% fatality; average survival, 448 days). Ann Diagn Pathol 5: 129-140, 2001. This is a US government work. There are no restriction on its use.

Pleomorphic (giant and/or spindle cell) carcinoma of lung shows a high percentage of variant CYP1A12.

BACKGROUND: Pleomorphic carcinoma (PC) of the lung is an aggressive epithelial neoplasm composed of giant and/or spindle tumor cells and associated with short survival. Most patients are cigarette smokers. The tumor susceptibility gene P-450 1A1 (CYP1A1) is involved in the activation of polycyclic aromatic hydrocarbons, including benzo[a]pyrene, producing DNA-damaging epoxides that lead to G:C-->T:A point mutations. Isoleucine (Ile)-valine (Val) and Val-Val genotypes of the CYP1A1 exon 7 polymorphism are associated with an increased risk for lung cancer in certain populations. METHODS AND RESULTS: We sought to determine whether 25 archival, formalin-fixed, paraffin-embedded PC samples had a modified CYP1A1 gene profile at exon 7 using allele-specific PCR amplification. KRAS mutation status was available for all samples. Previous investigations have shown 0.88 Ile-Ile, 0.12 Ile-Val, and rarely, Val-Val as normal baseline population frequencies. Conversely, the markedly different PC CYP1A1 population frequencies were more likely to have the heterozygote variant alleles: 0.24 (six cases, Ile-Ile) and 0.76 (19 cases, Ile-Val; P <.001). CYP1A1 genotypes were found to be similar in both tumor and nontumor samples in a given case. All KRAS-mutated cases were Ile-Val heterozygotes. CONCLUSION: The increased propensity for the variant CYP1A1 allele may be the contributing factor to PC pathogenesis and may also result from KRAS mutations in these tumors.

Adenosquamous carcinoma of the pancreas: a clinicopathologic series of 25 cases.

BACKGROUND: Adenosquamous carcinoma is a rare aggressive subtype of pancreatic adenocarcinoma. We describe the clinical, pathologic, and molecular characteristics of 25 of these lesions, the largest series to date. METHODS: Twenty-five cases of adenosquamous carcinoma of the pancreas diagnosed between 1961 and 1994 were retrieved from the files of the Endocrine Registry of the Armed Forces Institute of Pathology. Histologic features were reviewed, histochemical, immunohistochemical, and molecular (k-ras) studies were performed, and patient follow-up was obtained. RESULTS: The patients included 17 men and eight women, aged 28 to 82 years (mean, 65.4 y). The patients usually experienced weight loss (n = 17) or painless jaundice (n = 11), while also presenting with other abdominal symptoms. The tumors affected the head most frequently (n = 17), followed by the tail (n = 9) or body (n = 4). Five cases involved more than one anatomic region of the pancreas. Microscopically, all tumors demonstrated dual differentiation toward adenocarcinoma and squamous cell carcinoma. All cases tested were immunoreactive with keratin (AE1:AE3 and CK1), whereas other keratin markers were variably expressed: CK5/6 (88%), CK7 (68%), Cam5.2 (41%), and CK20(26%). CA-19-9 (84%) and CEA (74%) were positive in the majority of the cases. K-ras oncogene mutations were identified in seven of 13 cases. All patients died from their disease an average of 5.8 months after diagnosis (range, 1 to 33 months). CONCLUSIONS: Adenosquamous carcinoma of the pancreas represents a distinct clinical and pathologic entity, demonstrating the expected immunoprofile and k-ras oncogene mutation of a ductal origin, with a worse prognosis than ductal adenocarcinoma.

Fine needle aspiration of gastrointestinal stromal tumors.

OBJECTIVE: Gastrointestinal stromal tumors (GISTs) are uncommon mesenchymal tumors of the gastrointestinal tract. Fine needle aspiration (FNA) is one option for diagnosing GISTs before surgery. This study was designed to evaluate the clinical utility of FNA in the diagnosis of GISTs. STUDY DESIGN: FNAs from 19 GISTs originating in the stomach, small bowel and colon obtained from 1988 to 1998 were studied. Immunocytochemistry was performed on 12 cases. The GISTs were classified as benign, borderline and malignant, according to location, size, mitotic activity and clinical outcome. RESULTS: Benign (three) and borderline (five) GISTs were all spindle cell type; malignant GISTs included five spindle cell type and six epithelioid type. Most smears contained abundant cellular material. Benign and borderline GISTs of spindle cell type tended to have cells arranged in tightly cohesive clusters, while malignant GISTs were more likely to exhibit loosely cohesive groups with many single cells, occasional nuclear pleomorphism, hyperchromasia and irregular nuclear contours. Epithelioid-type GISTs mimicked adenocarcinoma. Mitoses were seldom observed in either type. CD117 (KIT protein product) was demonstrated by immunocytochemistry in 9 cases, CD34 in 11, desmin in 3, S-100 protein in 2 and smooth muscle actin in 6 cases. CONCLUSION: FNA can be used to diagnose GISTs as spindle cell and epithelioid types, but cytomorphology alone cannot be used to assess malignant potential. Immunocytochemical staining for CD117 is helpful in confirming the diagnosis. Care must be taken to differentiate epithelioid-type GISTs from adenocarcinoma.

Hemochromatosis (HFE) gene sequence analysis of formalin-fixed, paraffin-embedded liver biopsy specimens.

BACKGROUND: Hereditary hemochromatosis (HH) is a common disease predominantly characterized by mutations of the HFE gene. METHODS AND RESULTS: We investigated the utility of HFE gene sequence analysis in the diagnosis of HH in 61 prospectively accrued formalin-fixed, paraffin-embedded liver biopsy specimens with clinical or histologic features suggestive of HH. Mutations in codons 63 or 282 of the HFE gene were identified by direct sequencing; in 21 of these samples, quantitative hepatic iron testing was also performed. Changes characteristic of HH were present in 16 (26%) of the cases, and 54% of the cases showed HFE gene mutations. The most common alteration was homozygous mutation of codon 282 (11 cases, 18%), followed by the combined 63 + 282 heterozygous mutation (3 cases, 5%). Two cases (3%) showed biallelic mutation of codon 63. The other 28 cases (46%) showed no sequence abnormalities. Weak iron staining did not exclude HH; intense staining did not reliably predict HH. CONCLUSION: When HH is clinically and/or histologically suspected, HFE gene sequencing of formalin-fixed, paraffin-embedded liver biopsy specimens is a rapid and cost-effective approach to genotypic diagnosis of HH.

Analysis of KIT mutation and protein expression in fine needle aspirates of gastrointestinal stromal/smooth muscle tumors.

OBJECTIVE: To determine if sequencing the KIT gene could facilitate more definitive FNA diagnosis. STUDY DESIGN: Sixteen cases of gastrointestinal stromal/smooth muscle tumor (GIST) in which fine needle aspiration (FNA) was performed (mean age, 67; M/F = 12/4) were studied. DNA was extracted from cytologic preparations from all patients (15 cell blocks, 1 alcohol-fixed smear) and seven subsequent resection specimens. DNA was amplified by polymerase chain reaction, using primers designed to amplify a segment of the KIT gene exon 11 and sequenced on an ABI Prism 377 DNA sequence analyzer (Applied Biosystems, Indianapolis, Indiana, U.S.A.). Immunocytochemical staining for CD 117 (the KIT gene product) was performed on sections from 12 cell blocks and 7 surgical resections. RESULTS: In-frame deletion of exon 11 was detected in eight cases (7 monoalleic, 1 bialleic); a point mutation was found in one case. Mutation was found only in histologically malignant (6 of 10 cases) and borderline GISTs (3 of 4 cases). No mutation was identified in benign tumors. In three cases, scant cellularity or blood precluded sequencing. CD 117 was expressed in 12 of 15 cases. CONCLUSION: Immunocytochemical staining for CD 117 is useful in confirming a cytologic diagnosis of GIST but does not facilitate diagnosis of malignancy. FNA biopsy specimens are suitable for KIT gene sequencing; detection of a KIT mutation favors a malignant diagnosis, though absence of mutation does not preclude malignancy.

A clinicopathologic and immunohistochemical study of 22 intraductal papillary mucinous neoplasms of the pancreas, with a review of the literature.

Intraductal papillary-mucinous neoplasms (IPMNs) of the pancreas are rare lesions. We undertook this study to analyze these tumors by focusing on the diagnostic criteria and correlating the histologic features with clinical prognosis. Twenty-two cases of IPMN were retrieved from the Endocrine Tumor Registry of the Armed Forces Institute of Pathology. Blocks or unstained slides were available for histochemical and immunohistochemical studies (including proliferative markers and cell cycle regulators) and K-ras oncogene mutations in 15 cases. Patient follow-up was obtained in all of the cases. IPMN occurs in both genders with a slight male predominance, with a mean age at presentation of 64.4 years (range, 48-85 yr). The patients presented with abdominal pain. The neoplasms were radiologically and grossly cystic, usually (18 cases of 22) located in the head of the pancreas. Histologically, the tumors consisted of intraductal papillary proliferations protruding into and expanding the pancreatic ducts. Invasion into the surrounding pancreatic parenchyma was detected in 15 cases. Chronic pancreatitis was present in all of the cases. p27 immunoreactivity always exceeded the immunoreactivity of cyclin E. K-ras oncogene mutations were detected in two cases. Patients were treated with a complete surgical resection (n = 7) or a Whipple procedure (n = 13). Only 2 of 22 patients died of disease (3 died immediately postoperatively and 3 died of unrelated causes), whereas the remaining 14 patients were alive at last follow-up, without evidence of disease, an average of 58.2 months after initial presentation. IPMNs are rare, distinctive neoplasms, with complex intraductal papillae, that can be easily separated from in situ ductal adenocarcinoma and mucinous cystic neoplasms. The high ratio of p27 protein to cyclin E supports the excellent prognosis of these neoplasms, despite the presence of invasion and K-ras oncogene mutation.

Mucinous cystic neoplasm (mucinous cystadenocarcinoma of low-grade malignant potential) of the pancreas: a clinicopathologic study of 130 cases.

Mucinous cystic neoplasms (MCNs) of the pancreas are uncommon tumors. The classification and biologic potential of these neoplasms remain the subject of controversy. Attempts to classify these tumors in a similar manner to ovarian MCNs remains controversial, as even histologically benign-appearing pancreatic MCNs metastasize and are lethal. One hundred thirty cases of MCNs were identified in the files of the Endocrine Pathology Tumor Registry of the Armed Forces Institute of Pathology from the years 1979 to 1993. The pathologic features, including hematoxylin and eosin staining, histochemistry, immunohistochemistry (IHC), cell cycle analysis, and K-ras oncogene determination were reviewed. These findings were correlated with the clinical follow-up obtained in all cases. There were 130 women, aged 20-95 years (mean age at the outset, 44.6 years). The patients had vague abdominal pain, fullness, or abdominal masses. More than 95% of the tumors were in the pancreatic tail or body and were predominantly multilocular. The tumors ranged in size from 1.5 to 36 cm in greatest dimension, with the average tumor measuring >10 cm. A spectrum of histomorphologic changes were present within the same case and from case to case. A single layer of bland-appearing, sialomucin-producing columnar epithelium lining the cyst wall would abruptly change to a complex papillary architecture, with and without cytologic atypia, and with and without stromal invasion. Ovarian-type stroma was a characteristic and requisite feature. Focal sclerotic hyalinization of the stroma was noted. This ovarian-type stroma reacted with vimentin, smooth muscle actin, progesterone, or estrogen receptors by IHC analysis. There was no specific or unique epithelial IHC. K-ras mutations by sequence analysis were wild type in all 52 cases tested. Ninety percent of patients were alive or had died without evidence of disease (average follow-up 9.5 years), irrespective of histologic appearance; 3.8% were alive with recurrent disease (average 10 years after diagnosis); and 6.2% died of disseminated disease (average 2.5 years from diagnosis). Irrespective of the histologic appearance of the epithelial component, with or without stromal invasion, pancreatic MCNs should all be considered as mucinous cystadenocarcinomas of low-grade malignant potential. Pancreatic MCNs cannot be reliably or reproducibly separated into benign, borderline, or malignant categories.

Loss of heterozygosity at 1p36 predicts poor prognosis in gastrointestinal stromal/smooth muscle tumors.

Gastrointestinal stromal/smooth muscle tumors are uncommon neoplasms for which current criteria for diagnosing malignancy (size and mitotic index) sometimes fail to predict outcome. Cytogenetic studies reveal frequent chromosome 1 abnormalities in these tumors, but significant underlying molecular changes have not been elucidated, and their significance is unknown. DNA was obtained from the formalin-fixed, paraffin-embedded tissue of 80 gastrointestinal stromal/smooth muscle tumors. Tumors were topographically microdissected from surrounding normal tissue; microsatellite markers from tumor and normal tissue were amplified by PCR in the regions of chromosome 1p36 (D1S199, D1S228, D1S450, D1S214, D1S243), 1p12 (D1S418),1p13 (D1S252, D1S514), and 1q32(D1S103). The presence or absence of heterozygosity for each case was mapped at each informative marker. Relationships among loss of heterozygosity (LOH), tumor size, mitotic index, and survival were investigated using correlation analysis, Kaplan-Meier plots, and the Cox model. LOH at 1p36 was found in 24 of 80 cases, suggesting the possibility of a tumor suppressor gene at 1 p36 near the site of a suspected neuroblastoma tumor suppressor gene. Patients whose tumors demonstrated LOH at 1 p36 had significantly shorter survival (p = 0.017) than those whose tumors did not. LOH at 1 p36 retained independent prognostic significance in a multivariate model that included KIT mutation status and tumor size; the mitotic index, however, did not retain independent significance in such a model. LOH was observed at 1 p12-1p13 (most frequently at 1p13.3) in 19 of 80 cases, but loss of heterozygosity at this site did not influence survival. No LOH was observed near 1q32. These findings provide strong evidence for a prognostically significant tumor suppressor gene in the region of chromosome 1p36.3.

Adenocarcinoma simulating mesothelioma: a clinicopathologic and immunohistochemical study of 29 cases.

We report 29 cases of adenocarcinomas whose clinical, gross, and microscopic appearance resembled diffuse malignant pleural mesothelioma. Initial criteria for inclusion in the study included availability of an open pleural biopsy or decortication specimen and microscopic evidence of neutral (periodic acid-Schiff positive) mucin in the tumor. The median age of the patients was 63 years (range, 31 to 78 years), with a peak age in the seventh decade. There were 24 men and five women. Thirteen of them had a history of smoking; six (21%) had possible or definite occupational exposure to asbestos. Three (21%) of 14 lung specimens showed ferruginous bodies and two (14%) showed microscopic evidence of asbestosis. At least 25 patients had pleural effusion, most typically unilateral. Needle biopsy of pleura showed malignancy in 10 (77%) of 13 cases. Most (20 of 29) patients underwent pleural stripping. Radiotherapy and chemotherapy was each given to three patients without effect. Median survival by Kaplan-Meier estimate was 8 months, with an 18-month survival of 13%. Histologically, glands (23 cases), nests (13 cases), tubulopapillary arrays (12 cases), or sheets (eight cases) of tumor cells were found. Spindling of neoplastic cells was seen in 10% of cases. Three (21%) of 14 lung specimens showed a subpleural adenocarcinoma. Antibodies to polyclonal CEA, Ber-EP4, Leu-M1, and B72.3 were positive in 94%, 56%, 50%, and 44% of cases, respectively. All but one of the cases stained with two or more of the antibodies CEA, Ber-EP4, Leu-M1, or B72.3. This study indicates that adenocarcinomas simulating mesothelioma are aggressive variants of peripheral adenocarcinomas with a poor prognosis, that they can show pathological evidence of asbestos exposure in a subset of cases, and that immunohistochemical and histochemical stains are useful in their differential diagnosis with diffuse malignant mesotheliomas.

Microdissection-Based p53 Genotyping: Concepts for Molecular Testing.

p53 is the most commonly altered tumor-suppressor gene in humans, involved in the development and progression of many diverse forms of human cancer. Although much remains to be learned about the biology of this important growth regulatory gene, sufficient experience has been accumulated with respect to the occurrence and pattern of p53 mutational change to justify molecular diagnostic testing for specific objectives. The authors outline specific concepts for testing with particular emphasis for solid tumor molecular diagnostics. This article focuses on microdissection-based fixed tissue molecular analysis, introducing new considerations related to quality control appropriate for this type of methodology. Given the rapidly evolving nature of molecular genetics, the suggestions provided here should be viewed as flexible. Nevertheless, the concepts are intended to serve as a model for other oncogene/tumor suppressor-gene assays to be developed with the overall purpose of establishing informative integrated histopathologic/genetic molecular diagnostic testing to complement standard microscopic analysis.

p53 mutation spectrum in relation to GSTM1, CYP1A1 and CYP2E1 in surgically treated patients with non-small cell lung cancer.

p53 mutation status was analysed in relation to DNA polymorphisms of GSTM1, CYP1A1 and CYP2E1 from 105 surgically resected non-small cell lung cancer cases. Demographic factors, smoking, occupation, family history, tumour histology, grade and stage were taken into account. p53 mutations, detected either directly by DNA sequencing (P = 0.04, adjusted for smoking) or indirectly by immunostaining (P = 0.06), were overrepresented among CYP1A1 variants. Mutations in exon 8 and transitions at CpG sites in the p53 gene were favoured in this subset. There was no relation between the individual gene polymorphisms or p53 mutations and disease-free survival by Kaplan-Meier analysis. The finding of excess CYP1A1 heterozygotes in individuals with p53 mutations after adjustment for smoking suggests that CYP1A1 activation contributes to lung cancer via p53 inactivation.

KIT mutation portends poor prognosis in gastrointestinal stromal/smooth muscle tumors.

Gastrointestinal stromal/smooth muscle tumors (GISTs) are uncommon neoplasms for which current criteria for the diagnosis of malignancy (location, size, and mitotic index) do not always reliably predict patient outcome. Recently, mutation of KIT oncogene exon 11 has been observed in some of these tumors, but the relationship between mutation and clinical outcome has not yet been determined. DNA was obtained from the formalin-fixed, paraffin-embedded tissue of 35 gastric GISTs. A segment of exon 11 was amplified by PCR and sequenced on an ABI 377 sequencer. The relationship between the presence or absence of mutation, tumor size, and mitotic index was investigated using correlation analysis, and the relationship between mutation and outcome was investigated using Kaplan-Meier plots, the Cox-Mantel statistic, and the Cox regression model. Exon 11 deletion mutations were identified in 10 cases, and point mutations were identified in an additional 3 cases; 22 cases demonstrated no KIT mutations. KIT mutation was associated with decreased survival (p = 0.001), with fewer than 30% of patients surviving more than 3 years, compared with over 65% survival for patients whose tumors did not bear the mutation. KIT mutation did not correlate with either the mitotic index or the tumor size. In conclusion, KIT mutation is associated with poor prognosis in patients with gastrointestinal stromal tumors. Whether the KIT mutation will prove to be an independent prognostic factor awaits the completion of larger studies.

Primary germ cell tumors of the mediastinum: II. Mediastinal seminomas--a clinicopathologic and immunohistochemical study of 120 cases.

BACKGROUND: Primary seminomas of the mediastinum are unusual neoplasms that are morphologically indistinguishable from their gonadal counterparts but may have different biologic behavior because they arise at this particular location. METHODS: The clinical and pathologic features in 120 cases of primary mediastinal seminoma were reviewed, and the immunohistochemical staining patterns in 50 of these tumors were also analyzed. RESULTS: The patients were all men between the ages of 14 and 79 years (mean age, 46.5 years). Their clinical symptoms included cough, chest pain, and dyspnea. In some patients, the lesions were asymptomatic and discovered incidentally on routine chest radiographs. None of the patients had a previous history of testicular neoplasm or tumor elsewhere. Macroscopically, the tumors were described as soft and tan, with a slightly lobulated cut surface, and measured up to 16 cm in greatest dimension. Histologically, the morphologic features were similar to those of tumors occurring in the gonads, namely, a neoplastic proliferation of round-to-polygonal cells with indistinct cell borders, clear-to-lightly-eosinophilic cytoplasm with round-to-oval nuclei and prominent nucleoli, associated with a prominent inflammatory background composed mainly of mature lymphocytes. Necrosis, hemorrhage, multinucleated giant cells, granulomatous reaction, and remnants of thymic tissue were observed in a variable number of cases; mitoses were rare. Immunohistochemical studies in 50 cases showed cytoplasmic staining with placental alkaline phosphatase in 80% of the tumors, focal dotlike positivity for CAM 5.2 low-molecular-weight keratins in 75%, focal cytoplasmic staining for wide-spectrum keratin in 70%, focal positive reaction with vimentin in 70%, and focal positivity with HCG in singly scattered cells in 5%. Immunostains for carcinoembryonic antigen, epithelial membrane antigen, and alpha-fetoprotein were negative in all the cases studied. Fifty patients were Stage I, 3 patients were Stage II, and 12 patients were Stage III. Clinical follow-up information was obtained for 65 cases (54%). Forty-nine patients were alive and disease free after a period ranging from 1 to 19 years (mean follow-up, 10 years). Sixteen patients died within the same period and were found to have metastases to distant organs. Of the 16 patients who died, 6 showed extension of the tumor outside of the mediastinal compartment at the time of initial diagnosis (Stage III lesions). Aside from clinical staging, the authors' findings also suggest that patients >37 years have worse outcomes than younger individuals. The authors were unable to find any correlation between histopathologic features and clinical behavior in any of these cases. CONCLUSIONS: Clinical and pathologic staging of mediastinal seminomas are important parameters that can be useful in determining the clinical outcomes of patients with these tumors. Tumor invasion into adjacent organs represents a marker of increased morbidity and mortality. The authors' findings suggest that patients with mediastinal seminomas may have a very good prognosis when the diagnosis is made early; patients with more advanced lesions may require more aggressive therapy for improved local control and prevention of distant metastases.

Sporadic and Thorotrast-induced angiosarcomas of the liver manifest frequent and multiple point mutations in K-ras-2.

Hepatic angiosarcoma (HA) is an uncommon neoplasm associated with known etiologic factors in 25% to 42% of cases. It is, however, one of the most common sarcomas found in the liver. The aim of this study was to find was to find mutations in the K-ras-2 oncogene in sporadic and Thorotrast (TT)-induced HA. Point mutations in K-ras-2 were sought in archival, formalin-fixed tissue blocks from 24 patients with angiosarcoma. Of these, 19 cases were sporadic and 5 were TT-induced. Mutational analysis was performed by topographic microdissection with PCR amplification followed by genotyping. Specific mutations were determined by two independent methods: (a) direct sequencing of the PCR product confirmed by rePCR and by using a different sequencing primer, and (b) PCR-based selective enrichment of mutant DNA by endonuclease digestion followed by heteroduplex DNA analysis using denaturing gradient gel electrophoresis. Eleven K-ras-2 point mutations were detected in 7 of 24 (29%) tumors, including 5 of 19 (26%) sporadic HA and 2 of 5 (40%) TT-induced HA. There were seven G:C > A:T and four G:C > T:A mutations. All seven mutated tumors contained a codon 12-aspartate amino acid substitution. In addition, a second codon 12-cysteine mutant cell population was present in one of two codon 12-aspartate mutated TT-induced HA and in three of five codon 12-aspartate sporadic tumors. Of these four tumors, three contained both aspartate and cysteine mutations and were composed of multiple nodules; the fourth was a single mass. Seventeen tumors had multiple nodules; whereas 5 had a K-ras-2 mutation, 12 were wild-type. The molecular pathology of both sporadic and TT-induced HA is characterized by a high rate of K-ras-2 mutations characteristic of oxidative damage (ie, G:C > A:T and G:C > T:A mutations) resulting in two mutated population sets: codon 12 GGT > GAT and GGT > TGT (glycine to aspartic acid and cysteine). This is, to date, the first study to characterize the K-ras-2 gene mutations within human sporadic and TT-induced HA by direct sequence analysis and denaturing gradient gel electrophoresis. These data further support the hypothesis linking adduct-forming vinyl chloride exposure to HA containing a much higher frequency of K-ras-2 mutations and a mutational spectrum characteristic of chloroethylene oxide, a carcinogenic metabolite of vinyl chloride.

Pleomorphic (giant and spindle cell) carcinoma is genetically distinct from adenocarcinoma and squamous cell carcinoma by K-ras-2 and p53 analysis.

Pleomorphic carcinoma (PC) of lung is a poorly differentiated epithelial neoplasm predominantly composed of pleomorphic giant and/or spindle tumor cells. The WHO classification of lung cancer recognizes spindle cell carcinoma and giant cell carcinoma as separate neoplasms related to squamous cell carcinoma (SqC) and large cell carcinomas, respectively. Further, the presence of foci of SqC or adenocarcinoma (AdC) in, respectively, 10% and 45% of PC produces additional uncertainty as to the distinctive nature of this tumor type. In this study, the authors tested the hypothesis that PC is an entity separate from SqC or AdC by evaluating the mutational spectrum seen in these tumor types. This is performed by documenting and comparing mutation type and rate of K-ras-2 and p53 genes in PC, SqC, and AdC. Comparative DNA sequence and immunohistochemical analysis were performed on 22 PC, 42 SqC, and 97 AdC. Archival formalin-fixed, paraffin-embedded tissues formed the basis of the study. Immunohistochemical staining with p53 antibody (DO-7) revealed statistically significant differences in the intensity and frequency of staining of PC (weak, 86% of cases) versus SqC (strong, 52% of cases) and AdC (strong, 27% of cases) (P < .001). Topographic genotyping with subsequent polymerase chain reaction (PCR) and sequence analysis of K-ras-2 showed mutations in significantly fewer cases of PC (9%, 2 of 22 cases) than in AdC (36%, 35 of 97 cases) or SqC (0%, 0 of 42 cases) (P < .001). Pleomorphic carcinoma also showed significantly fewer p53 point mutations (14%, 3 of 22 cases) than did AdC (27%, 26 of 97 cases) of SqC (43%, 18 of 42 cases) (P < .01). Finally, the p53 mutations in PC were more common in exon 7, whereas those in SqC and AdC were more frequent in exon 8. These findings reveal significant differences in the pattern and frequency of genetic mutations between PC and pulmonary SqC and AdC and are in keeping with the separate histopathologic classification of these tumors.

Primary mediastinal and testicular seminomas: a comparison of K-ras-2 gene sequence and p53 immunoperoxidase analysis of 26 cases.

Primary mediastinal seminomas (MS) are rare tumors. Histologically, they are similar to their counterpart in the gonads. The survival rate has varied from 50% to 85% in different series. However, large series of these tumors primarily in the mediastinum are lacking. At the molecular level, a few reports document K-ras mutations in up to 40% of testicular seminomas (TS), localized predominantly to codon 12. Reports on TS p53 immunohistochemistry (IHC) range from negative to overexpression approaching 90% of cases, and by sequence analysis one small series showed a 23% mutation rate. To date, no analyses have been performed for either K-ras mutations or p53 immunohistochemical expression in primary MS. The authors studied 13 cases each of primary MS and TS from archival formalin-fixed, paraffin-embedded sections in which adequate tumor sampling and clinical history, including serological studies, and histological, histochemical, and IHC staining, were performed to confirm the diagnosis. p53 immunoperoxidase staining using citrate buffer/microwave antigen retrieval was performed. Topographic genotyping was performed on 5-microns-thick tissue sections up to 17 years old, in which the neoplastic cell population was sampled. Additionally, multiple sites within a given cases were sampled to determine clonality of the tumor cell population. Polymerase chain reaction and subsequent sequence analysis of the K-ras-2 exon-1 gene was used for mutation analysis. Focal weak staining with p53 IHC was observed in 4 of 13 (31%) MS and 10 of 13 (77%) TS cases, with all remaining cases being negative (P < .05). Only one MS case (8%) showed K-ras mutation (codon 13 GGC > GAC; glycine > aspartate), which is in contrast to 2 of the TS cases (15%), showing codon 12 mutations. All the remaining cases were wild type. Therefore, primary mediastinal seminomas appear to be different in their K-ras sequence and p53 immunostain profile from TS. Codon mutation type may be useful in determining primary versus metastatic origin of a mediastinal seminoma.

Comparison of DNA topoisomerase II alpha expression in small cell and nonsmall cell carcinoma of the lung. In search of a mechanism of chemotherapeutic response.

BACKGROUND: Small cell carcinoma of the lung (SCLC) is distinguished from nonsmall cell carcinoma (NSCLC) by its exquisite initial sensitivity to chemotherapy. Antineoplastic drugs effective against SCLC include doxorubicin, etoposide, and others. Recently, the molecular target of these drugs has been identified as the alpha form of DNA topoisomerase II, which is important in DNA replication and in the separation of chromosomes during normal cellular division. In this study we compared DNA topoisomerase II alpha expression in SCLC and NSCLC by immunohistochemistry. We hypothesized that the sensitivity of SCLC and relative insensitivity of NSCLC to these chemotherapeutic agents stem from different frequencies of DNA topoisomerase II alpha expression. METHODS: DNA topoisomerase II alpha expression was analyzed in 17 cases of SCLC and 24 cases of NSCLC by immunohistochemistry utilizing a monoclonal antibody recognizing the alpha isoform of DNA topoisomerase II. A topo II index was determined by dividing the number of tumor nuclei expressing DNA topoisomerase II by the total number of tumor nuclei counted. RESULTS: A significantly higher frequency of DNA topoisomerase II alpha expression was identified in SCLC (P < 0.001). The average topo II index for SCLC was 0.60 (range: 0.45-0.76) compared with NSCLC, 0.31 (range: 0.05-0.75). CONCLUSIONS: We conclude that DNA topoisomerase II alpha is expressed at a higher frequency in SCLC than in NSCLC, and that this expression is possibly involved in the response of SCLC to chemotherapeutic agents.