Myxomatous neoplasms in the perineal region of baboons.

BACKGROUND: In baboons, Papio sp. neoplasms tend to affect the hematopoietic system most commonly, with rare documentation of myxomatous neoplasms. In contrast, women can develop myxomatous masses within deep peripelvic tissues with some frequency during their reproductive years. METHODS: We have identified and examined, retrospectively, myxomatous perineal masses in twelve female baboons within one research facility and compared their histopathologic, immunohistochemical and electron microscopic features to their human variants. RESULTS: Our results indicate that these myxomatous neoplasms, in humans and non-human primates, share common features. CONCLUSION: Further research, particularly molecular genetic analysis, may be needed to identify the baboon as a true animal model for myxomatous perineal neoplasms.

Primary extracranial meningioma of the pelvis: a light microscopic, immunohistochemical, and ultrastructural study.

BACKGROUND: Extracranial meningiomas are rare tumors which have been described in head and neck. The occurrence in mediastinum and retroperitoneum is even rarer. This presented case records a unique location, a meningioma arising in pelvis. CASE: A 52-year-old woman presented with an ovarian mass. The histology of the resected tumor revealed sheets of bland epithelioid cells arranged in prominent whorls with psammoma bodies typical of meningothelial meningioma. Immunohistochemical analysis demonstrated diffuse strong positivity for vimentin and epithelial membrane antigen (EMA). There was moderate reactivity for cytokeratin, estrogen (ER) and progesterone (PR) receptors. By electron microscopy, the tumor cells expressed desmosomes and abundant intermediate filaments. CONCLUSION: According to our review of literature, this is the first reported case of a primary pelvic meningioma. Its benign appearance and 4-year disease-free survival without clinical or radiological evidence of intracranial disease favors the pelvis as the primary site.

Atypical pleomorphic epithelioid angiomyolipoma localized to the pelvis: a case report and review of the literature.

AIMS: Angiomyolipoma is the most common mesenchymal tumour of the kidney. It has been reported in several other sites outside the kidney, mainly in the liver. We report the first case of atypical pleomorphic angiomyolipoma in a man, arising from the pouch of Douglas and extending to the entire abdominal cavity. METHODS: A 17-year-old man underwent a complete resection of a giant abdominopelvic mass. The tissue was formalin fixed and paraffin embedded and 4 micro m thick histological sections were stained with haematoxylin-eosin. Immunohistochemical stains for HMB-45, smooth muscle actin, vimentin, calponin, S100 and desmin were performed. Sections for electron microscopy were also prepared. RESULTS: Microscopic examination revealed a neoplasm composed of pleomorphic epithelioid cells with atypical features, immunoreactive for HMB-45, MART-1, actin, vimentin and calponin, while S100 protein and desmin stains were negative. Ultrastructurally, the tumour cells showed prominent nucleoli, vacuolated cytoplasm, and some premelanosomes. A diagnosis of atypical pleomorphic epithelioid angiomyolipoma was then made. CONCLUSIONS: To date five patients with abdominal epithelioid angiomyolipoma have been described in the literature. All were women. Three of the five patients reported developed metastasis, while our patient is still free of disease at 16 months of follow-up. Clear prognostic pathological features have not been identified.

Leiomyosarcoma of the broad ligament arising in a pre-existing pure neurilemmoma-like leiomyoma.

A 35-year-old woman presented with an adnexal mass which came out as a leiomyosarcoma of the broad ligament arising in a pre-existing pure neurilemmoma-like leiomyoma. This is the first reported case of leiomyosarcoma arising in a pure neurilemmoma-like leiomyoma, the third reported case at an unusually young age showing evidence of a pre-existing leiomyoma and the 12th reported case of leimyosarcoma of the broad ligament. Is the likelihood of malignant transformation, especially in large leiomyomas of the broad ligament, a rare event?

Peripheral primitive neuroectodermal tumor (PPNET) of pelvic origin: report of a case arising from an unusual location.

We report a rare case of a peripheral primitive neuroectodermal tumor (PPNET) originating from the left ileopsoas muscle in an adult patient with neoplastic thrombosis of the left external iliac vein, the common femoral vein and the left popliteal vein. We performed a median laparotomy with an oblique left inguinal incision to remove the neoplasm, which consisted of a large mass surrounding the iliac-psoas muscles, extending from the transverse apophysis of the spinal column to Scarpa's triangle, and passing through the lacuna musculorum. Histopathological examination revealed a primitive neuroectodermal tumor (PNET) with focal areas of necrosis, hemorrhage and vascular invasion. Immunophenotyping was positive for CD99, NSE, and focally for CK. Ultrastructural examination of the neoplastic cells showed often multiple nuclei with dense chromatin and very large nucleoli. The patient was discharged ten days after the operation. Adjuvant treatment consisted of radiotherapy at a dose of 2000 cGy in five fractions followed by six cycles of chemotherapy. The venous thrombosis was treated by anticoagulant therapy and recanalization of the occluded veins was obtained after two months of therapy. An MRI scan, carried out 12 months later, showed a local relapse, which was treated with chemotherapy and arterial chemoembolization.

Desmoplastic small round cell tumor: II: an ultrastructural and immunohistochemical study with emphasis on new immunohistochemical markers.

In order to investigate the histogenesis and facilitate the diagnosis of desmoplastic small round cell tumor (DSRCT), 39 cases were studied by immunohistochemical methods using a large battery of antibodies directed against a wide variety of epithelial, mesenchymal, and neural-associated proteins. Sixteen of these tumors were also studied by electron microscopy. Thirty-seven of 39 cases reacted for cytokeratin using a "cocktail" of 3 monoclonal antibodies (CAM 5.2/AE1/AE3), 39/39 for desmin, 24/25 for epithelial membrane antigen, 22/27 for vimentin, 18/25 for neuron-specific enolase, 10/15 for CD57 (Leu-7), 3/19 for synaptophysin, 1/22 for chromogranin, 3/19 for muscle-specific actin, 3/16 for alpha-smooth-muscle actin, 11/16 for CD15 (Leu-M1), 5/12 for CA-125, 6/17 for CD99, 9/10 for MOC-31, 2/6 for NB84, 5/7 for Ber-EP4, and 8/9 for the Wilms tumor (WT1) protein. No staining was obtained in any of the cases tested for cytokeratin 5/6 or 20, neurofilament proteins, glial fibrillary acidic protein, peripherin, CA19-9, thrombomodulin, alphafetoprotein, carcinoembryonic antigen, TAG-72 (B72.3), placental alkaline phosphatase, S-100 protein, HMB-45, myoglobin, or for the two myogenic regulatory proteins myogenin and MyoD1. A frequent ultrastructural finding was the presence of juxtanuclear aggregates of intermediate filaments, but microfilaments with densities or Z-band-like material suggestive of either smooth or skeletal muscle differentiation were not seen in any case. Dendritic-like processes containing microtubules and dense core granules were seen in four tumors and all of these tumors reacted for at least one of the neural markers investigated. Although ultrastructural and immunohistochemical studies confirmed previous observations that DSRCTs present epithelial, mesenchymal, and neural phenotypes, a great variation was found in the frequency of expression of the different markers used to demonstrate each line of cell differentiation. The absence of expression of cytokeratin 5/6 and thrombomodulin together with positive staining for CD15, MOC-31, and Ber-EP4 argues against the possible mesothelial origin that has been suggested for this tumor. Additionally since none of the tumors reacted for myogenin or MyoD1, desmin expression in DSRCT cannot be regarded as evidence of skeletal muscle differentiation. Although the histogenesis of DSRCT remains unknown, it is believed that this tumor originates from a progenitor cell with potential for multiphenotypic differentiation.

Expression of epidermal growth factor receptor in urinary bladder cancer metastases.

Bladder cancers frequently exhibit an increased number of epidermal growth factor receptors (EGFR) in comparison to normal urothelium. The EGFR could potentially be a target for toxic conjugates. The aim of our study was to compare the expression of EGFR in metastases with concurrent or primary tumour in the urinary bladder using immunohistochemical techniques and a monoclonal antibody. Tumour material from 20 patients was investigated. The majority (13/20) of the metastases were homogeneously stained and showed a moderate to strong membranous staining for EGFR. The expression of EGFR in primary bladder tumours and metastases was similar. There was no indication that tumour tissue exposed to chemotherapy or radiation had a decreased number of EGFR. Targeting of the EGFR thus seems potentially applicable to metastatic disease.

Perianal ependymoma presenting in the neonatal period.

Extraspinal ependymomas are a rare type of glioma that may arise in the sacrococcygeal region, presenting as a pelvic mass in an infant or child. Ependymoma presenting in the newborn period has not been described previously. Herein we describe a case of a newborn boy who presented with a perianal ependymoma, which was subsequently found to have presacral extension. The major diagnostic challenge this case presented was to rule out the alternative diagnosis of sacrococcygeal teratoma or a developmental malformation/heterotopia.

Rhabdomyosarcoma. Morphologic, immunohistochemical, and DNA study.

In this study 80 cases of predominantly adult rhabdomyosarcoma are presented as follows: 20 cases of the embryonal type, 32 cases of the alveolar and 8 cases of the pleomorphic type. Additional histologic classification was performed in each type. In myotube stage the histologic picture of fetal muscles cannot be compared to the alveolar type of rhabdomyosarcoma. Desmin and sarcomeric actin are observed in 47.7% of all cases, and myoglobin and myosin in only 23.1%. The reactions were diffuse, disperse, or focal. Electron microscopic study subdivides desmin positive tumors into three groups of differentiation. DNA analysis shows that most desmin positive cells are diploid in comparison to all the tumor cells that are hyperdiploid and tetraploid.

Myxofibrosarcoma. Clinicopathologic analysis of 75 cases with emphasis on the low-grade variant.

Myxofibrosarcoma is one of the most common sarcomas in the extremities of elderly patients. We analysed the clinicopathologic features in a series of 75 patients. All patients were adults (range, 22-91 years; median, 66 years) with an approximately equal incidence in men and women. Thirty-five tumors arose in the lower and 25 in the upper extremities, nine on the trunk, two each in the retroperitoneum and the head and neck region, and one each in the pelvis and penis. Forty-eight cases (69.5%) were located in dermal or subcutaneous tissues. Distinctive histologic features included the following: a commonly nodular growth pattern; a myxoid matrix containing elongated, curvilinear capillaries; and fusiform, round or stellate tumor cells with indistinct cell margins, slightly eosinophilic cytoplasm, and hyperchromatic atypical nuclei. These lesions varied from a hypocellular, mainly myxoid, and purely spindle-cell appearance (low-grade neoplasms) to high-grade, pleomorphic (malignant fibrous histiocytoma-like) lesions with multinucleated giant cells, high mitotic activity, and areas of necrosis. Immunohistochemistry in 44 cases revealed only vimentin and occasional actin positivity. Ultrastructurally, tumor cells had a fibroblastic phenotype. DNA flow cytometry and proliferation analysis showed an association between aneuploidy and histologic grade. An average follow-up of 45 months (range, 5-300 months) in 60 cases has revealed local recurrence in 33 cases (54%). Thirteen patients developed metastases, and 13 tumor-related deaths occurred. A short interval to first local recurrence was associated with poor clinical outcome. The rate of local recurrence was independent of histologic grade, but only intermediate and high-grade neoplasms metastasized. The depth of the primary lesion did not influence the incidence of local recurrence. However, in deep-seated neoplasms, the incidence of metastases was higher and the percentage of tumor-related deaths was twice as high as in superficially located lesions, reflecting the fact that deep-seated lesions tended to be higher-grade, larger tumors. Myxofibrosarcoma tends to become progressively higher grade in recurrences, as demonstrated in five cases in our series. The poorly recognized low-grade myxofibrosarcoma is emphasized, as proper diagnosis and treatment and scrupulous follow-up are mandatory to avoid local recurrence and gradual tumor progression to a higher-grade neoplasm that may then metastasize.

Aggressive angiomyxoma of the pelvioperineal region. Immunohistological and ultrastructural study of seven cases.

We describe seven cases of aggressive angiomyxoma of the pelvioperineal region. In three cases, we observed immunohistochemical signs of myoid differentiation in the tumor cells. In one of these cases, we could confirm the myoid differentiation at the ultrastructural level. The other four cases were devoid of this differentiation. We further discuss the relationship of aggressive angiomyxoma to the recently described angiomyofibroblastoma of the vulva.

Keratin-positive, epithelial membrane antigen-positive solitary pelvic tumor with ultrastructural features of large cell lymphoma.

A case of an unusual malignant solitary pelvic tumor is presented. The neoplastic cells were positive for keratin and epithelial membrane antigen. Although ultrastructural features (prominent nuclear pleomorphism, abundant polyribosomes, and absence of cell junctions) were those typically seen in large cell lymphomas, lymphoid markers were not detected, and immunoglobulin heavy-chain gene and T-cell receptor beta-chain gene rearrangements were not identified. Combination chemotherapy resulted in complete remission.

Lipid-rich rhabdomyosarcoma--a potential source of diagnostic confusion.

Rhabdomyosarcoma is an often primitive tumor capable of diverse morphologic manifestations. The article describes three cases of childhood rhabdomyosarcoma in which a significant population of lipid-rich tumor cells was present. The lack of specificity and potentially confusing nature of this feature are discussed, and the ultrastructural diagnosis of rhabdomyosarcoma is briefly reviewed.

Primitive pelvic sarcoma resembling clear cell sarcoma of kidney.

Clear cell sarcoma of kidney (CCSK) is an aggressive childhood renal tumor of unknown histogenesis that has not been reported to occur outside the kidney. The article describes an extrarenal neoplasm arising in the pelvic soft tissues of a 13-year-old boy that was composed predominantly of uniform mesenchymal cells with optically clear cytoplasm supported by an arborizing network of small blood vessels, which was indistinguishable in appearance from CCSK. The electron microscopic findings, although nonspecific, were essentially identical to those of CCSK, with tumor cells displaying fine chromatin, electron-lucent cytoplasm, and intercellular collagen but no evidence of tissue-specific differentiation. Immunocytochemical studies showed positivity for vimentin but negative results for desmin, myoglobin, cytokeratin, epithelial membrane antigen, S-100 protein, neuron-specific enolase and factor VIII-related antigen. Tumor cells were also nonreactive with Ulex lectin. This unusual pelvic tumor and CCSK may both derive from primitive mesenchymal cells and may represent phenotypic but not necessarily histogenetic analogs.

Extrarenal primitive malignant tumor with rhabdoid features: fine-needle aspiration cytology, immunocytochemistry, and electron microscopy of a case.

We describe a malignant pelvic tumor with rhabdoid-like features that arose in the sacroiliac region of a 15-year-old girl. Fine-needle aspiration (FNA) cytology showed large cells with glassy cytoplasm, globular hyaline cytoplasmic inclusions, and prominent nucleoli. Immunocytochemical methods applied to FNA material revealed immunoreactivity for cytokeratin, epithelial membrane antigen, and vimentin; the cells failed to react with antibodies to desmin. This distinct appearance and phenotype was most consistent with a diagnosis of extrarenal malignant rhabdoid tumor. Electron microscopy confirmed this interpretation, showing whorled filamentous aggregates in the cytoplasm of the tumor cells.

Immunohistochemical localization of five classes of intermediate filament in a benign pelvic soft tissue tumor of rhabdoid appearance.

A benign pelvic soft tissue tumor from a 50-year-old woman was examined by immunohistochemistry and electron microscopy. The tumor cells had abundant eosinophilic cytoplasm with a hyaline appearance, which was filled with large aggregates of intermediate-sized filaments (IF). The cells were positively immunostained by antibodies against cytokeratin, vimentin, desmin, glial fibrillary acidic protein, and neurofilament proteins. This case represents an extreme example of the simultaneous expression of IF by neoplastic cells, and exemplifies the limited applicability of immunohistochemical detection of IF antigens for pathological diagnosis of neoplasms.

Aggressive angiomyxoma of the pelvis and perineum. Report of a case with immunohistochemical and electron microscopic study.

A case of aggressive angiomyxoma (AAM) of the pelvis and perineum is reported, whose clinical and pathological findings are consistent with the literature. This is a clinicopathological entity recently described by Rosai and colleagues (1983) who stressed its locally infiltrative nature and its tendency to recur. Its differential diagnosis includes a series of benign and malignant soft tissue tumours.

Selective use of electron microscopy in fine needle aspiration cytology.

The utility of electron microscopy (EM) applied to fine needle aspiration (FNA) biopsy specimens was analyzed in order to determine the role and the diagnostic contribution of the EM examination. A rapid stain (Diff-Quik) was used to obtain a preliminary diagnostic impression and to assure the adequacy of the EM specimen for problematic cases. Our experience suggests that EM is being relied upon with greater frequency in the study of FNA specimens because it is an accurate and cost-effective diagnostic procedure. The use of a rapid interpretation (Diff-Quik stain) enhances the quality of the EM specimen and, as in surgical pathology, the EM examination increases the accuracy and specificity of the FNA biopsy diagnosis.

Malignant rhabdoid tumour of soft tissue. An ultrastructural and immunohistological study of a pelvic tumour.

A case of extrarenal malignant rhabdoid sarcoma arising in the pelvic soft tissues of a 12-year-old girl is described. By routine light microscopy the tumour resembled, in some areas, an embryonal rhabdomyosarcoma and, in other areas, a neuroblastoma. Electron microscopy revealed characteristic cytoplasmic aggregates of intermediate filaments, often with central clusters of organelle membranes surrounded by these filaments. Immunohistochemical stains showed strong cytoplasmic reactivity for vimentin. Staining for cytokeratin, myoglobin, desmin, neurofilaments, neurone specific enolase, S-100 protein and leucocyte common antigen was negative. A histogenetic origin from primitive mesenchymal cells is favoured. We strongly support the use of electron microscopy for the definitive diagnosis of small round cell undifferentiated sarcomas of childhood.