Cases reported "Peritoneal Neoplasms"

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1/12. Mesotheliomas with deciduoid morphology: a morphologic spectrum and a variant not confined to young females.

    Deciduoid mesotheliomas are rare with only four previously reported cases, all affecting the peritoneum of young females. We describe another six cases (three men and three women; age range 52-65 yrs, median 55 yrs; five peritoneal and one pleural). Three patients had an occupational history of asbestos exposure. The deciduoid appearance predominated in four cases, whereas in two it represented a minor component within conventional tubulopapillary epithelioid mesothelioma. All tumors were strongly cytokeratin-positive (including CK5/6) and all showed at least focal staining for thrombomodulin, HBME-1, and calretinin. All were negative for epithelial mucin (D/PAS), CEA, BerEP4, LeuM1 (CD15), CD21, CD35, and S100 protein. Five of six cases (83%) were vimentin-positive and two (33%) were focally positive for alpha-smooth muscle actin. A differential diagnosis of gastrointestinal autonomic nerve tumor (GANT) had been initially considered from the morphology of one case, and we found positivity for some of the "neuronal" markers described in GANTs. This prompted us to apply such a panel to the other five tumors, accepting that the cytokeratin positivity encountered in all of our cases would exclude GANT. All cases of deciduoid mesothelioma (100%) were positive for PGP 9.5 and NSE and four of six (66%) were positive for NKI/C3. Weak focal staining (<5% cells) for synaptophysin was seen in two of six tumors. All cases were chromogranin-negative. All cases examined by electron microscopy showed desmosomes and smooth microvilli without rootlets but no neuroendocrine granules. In conclusion, a deciduoid morphology appears to be part of the histopathologic spectrum encountered in epithelioid mesothelioma. This variant is not confined to female patients and occurs over a wider age range than previously recognized. The overlapping immunophenotype with GANTs illustrates that caution should be exercised when interpreting positivity for "neuronal" markers in this context. An immunohistochemical panel that includes cytokeratins should always be used.
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2/12. 'Mucin-positive' epithelial mesothelioma of the peritoneum: an unusual diagnostic pitfall.

    AIMS: The histopathological, immunohistochemical and ultrastructural features of a primary 'mucin-positive' epithelial mesothelioma of the peritoneum are reported to draw attention to a potential cause of diagnostic error. methods AND RESULTS: light microscopy showed an infiltrative neoplasm within the gastric wall and omentum which was composed of sheets of 'signet- ring' tumour cells and contained abundant diastase-resistant periodic acid-Schiff-positive material. immunohistochemistry supported a mesothelial phenotype (cytokeratin AE1/3, thick membranous HBME-1, focal thrombomodulin and calretinin expression and no reactivity for carcinoembryonic antigen, Leu-M1 and Ber-EP4). Ultrastructural features showed large cells with prominent intercellular desmosomes and numerous delicate, elongated microvilli. Within intracytoplasmic neolumina, crystalloidal 'fern-like' bodies were identified with features similar to the ultrastructural appearances of hyaluronic acid crystals. Repeat histochemical analysis following hyaluronidase pretreatment revealed a significantly diminished diastase-resistant periodic acid-schiff reaction. CONCLUSIONS: This case of primary peritoneal 'mucin-positive' epithelial mesothelioma demonstrates morphological and histochemical mimicry with diffuse gastric adenocarcinoma. A similar case has not been previously reported in the peritoneum and an awareness of the tumour (with application of suitable ancillary studies) prevents misdiagnosis and assists in potentially difficult medicolegal cases.
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3/12. Malignant peritoneal mesothelioma in childhood with long-term survival.

    A diffuse, well-differentiated, malignant peritoneal mesothelioma (MPM) developed in a nine-year-old girl. She received limited chemotherapy and radiation therapy and is alive and well without clinical evidence of disease 109 months after diagnosis. The neoplastic cells stained immunohistochemically for cytokeratin and epithelial membrane antigen but were unreactive with B72.3, anti-carcinoembryonic antigen, and anti-Leu-M1. Ultrastructurally, the tumor cells had abundant desmosomes, numerous tonofilament bundles, and variable-length microvilli. These findings confirm the mesothelial nature of the cells. Features consistent with malignancy included dna aneuploidy by flow cytometric analysis and diffuse peritoneal involvement. The three previously described survivors with MPM were also premenarchal girls. Some MPMs in premenarchal girls have an indolent biologic behavior similar to that of low-grade peritoneal serous neoplasia or well-differentiated papillary mesothelioma in adult women.
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4/12. Diffuse malignant peritoneal mesothelioma in a young woman with a high serum level of CA125.

    An autopsy case of diffuse malignant peritoneal mesothelioma in a young woman who showed a high serum level of CA125 is reported. autopsy revealed extensive tumor involvement of the visceral and parietal peritoneum. The liver, spleen and other abdominal viscera were encased by tumor nodules. Histologically, the polygonal tumor cells were arranged mostly in a sheet-like fashion with a few tubular or papillary forms. No PAS reaction-positive mucin was recognized, but there was a strongly positive colloidal iron reaction. The colloidal iron positivity was effaced after combined treatment with hyaluronidase and sialidase. Immunohistochemically the tumor cells showed strongly positive reactions for CA125, epithelial membrane antigen (EMA) and cytokeratin, weak positivity for carcinoembryonic antigen (CEA) and focal positivity for vimentin. Ultrastructurally, the most characteristic feature was the expression of numerous long microvilli projecting from the tumor cell surfaces and abundant long desmosomes between the tumor cells. We consider that pretreatment using a combination of hyaluronidase and sialidase might be useful for the diagnosis of malignant mesothelioma. CA125 staining should be performed routinely in cases where this tumor is suspected.
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5/12. Malignant mesothelioma of peritoneum.

    A 57-year-old man with malaise, ascites, and abdominal pain was found to have a peritoneum studied with numerous, small nodular tumor masses. light microscopy revealed an anaplastic malignant tumor of uncertain differentiation. Mucin stains were negative. Electron microscopy revealed pleomorphic tumor cells with diffusely distributed cytoplasmic tonofilaments and well-developed true desmosomes. No long, thin, branching microvilli were present, yet tumor cells were strongly positive for both callus keratin (polyclonal) and monoclonal cytokeratin (AE1/3) in a diffuse cytoplasmic distribution (a pattern corresponding to the diffuse cytoplasmic tonofilaments). Tumor cells were negative for Leu-M1 and carcinoembryonic antigen. The findings were most consistent with malignant mesothelioma, and additional questioning, after tissue diagnosis, revealed a work history of asbestos exposure.
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6/12. An autopsy case of peritoneal malignant mesothelioma in a radiation technologist.

    A case of peritoneal malignant mesothelioma in a radiation technologist, who had worked in this field for 34 years, is reported. Histopathologically, a biopsy specimen from the retroperitoneal tumor revealed a biphasic type of malignant mesothelioma. Electron microscopy disclosed that the tumor cells contained prominent microvilli, basal laminae adjacent to the stroma, junctional complexes, desmosomes, tonofilaments, clusters of glycogen granules, well developed rough endoplasmic reticulum (RER), confronting cisternae showing direct continuity with the RER and membrane-bound granules suggestive of secretory activity. No increased amount of asbestos was detected in autopsied lung material or the peritoneal mesothelioma. The estimated cumulative dose of occupational irradiation was calculated to be about 40 to 50 rad at most. Irradiation was discussed in relation to the etiology of the peritoneal mesothelioma.
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7/12. Multicystic peritoneal mesothelioma: a case report.

    A case of recurrent cystic peritoneal mesothelioma is reported. Ultrastructurally the tumour cells showed abundant surface microvilli, desmosomes, intracytoplasmic filaments and well-developed basal lamina. The cells demonstrated positive staining for keratin peptides, vimentin and epithelial membrane antigen and, some of them, for carcinoembryonic antigen. No staining was demonstrable for a number of endothelial markers. The findings are in accord with the proposed mesothelial origin of the neoplasm and can be of help in the differential diagnosis of other multicystic neoplasms arising in the peritoneal cavity.
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8/12. Ultrastructure of poorly differentiated diffuse epithelial mesotheliomas.

    In differentiating diffuse epithelial mesothelioma from metastatic adenocarcinoma in pleural and peritoneal biopsies, the number and form of microvilli and the amount and distribution of tonofilaments are thought to be the most useful criteria. This report details 5 cases of diffuse epithelial mesothelioma in which the characteristic fine structural features of neoplastic mesothelial cells were markedly modified. The majority or all tumor cells were poorly differentiated in electron micrographs, particularly with reduced prominence or absence of intermediate filaments, desmosomes, intracytoplasmic lumina, and microvilli. immunohistochemistry revealed the absence of carcinoembryonic antigen and the presence of cytokeratin in all cases. Comparison with a better differentiated case suggests cytologic details that are useful in distinguishing the poorly differentiated type of epithelial mesotheliomas from adenocarcinoma. These include a mosaic pattern of closely associated tumor cells with a few long, narrow cytoplasmic processes lying parallel to adjacent plasma membranes, abundant cytoplasm with limited organelles usually having a polar arrangement, and nuclei with markedly disaggregated chromatin and prominent nucleolonemal-type nuclei.
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9/12. Occluding junctions in an epithelioid mesothelioma: a freeze-fracture study.

    The presence of a well-developed tight junction system in a case of diffuse, papillary, malignant mesothelioma of the peritoneum is documented using the freeze-fracture methodology. The mean number of strands within the tight junction network was determined to be 3.83 /- 0.16. In addition, the tight junctions were specifically located in regions of the plasma membrane adjacent to recognizable microvilli. gap junctions and desmosomes were found in close association with the occluding complexes; however, they were also seen in areas of the plasma membrane quite distinct from those that exhibit tight junction differentiation. The possible significance of the presence of tight junctions in neoplastic epithelial cells is also discussed.
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10/12. Concomitant malignant mesothelioma of the pleura, peritoneum, and tunica vaginalis testis.

    We describe the cytohistological, immunohistochemical and ultrastructural findings in a 55-yr-old-man with history of asbestos exposure and diffuse malignant mesothelioma (DMM) of the pleura, peritoneum, and tunica vaginalis presenting with chest pain and scrotal swelling. Pleural fine-needle aspiration (FNA) revealed mesenchymal elements and spindle-shaped epithelial-like cells, while biopsy showed pure sarcomatous tumor invading lung parenchymal. In both samples tumor cells coexpressed cytokeratin and vimentin. Peritoneal and hydrocele effusions contained aggregates of malignant mesothelial cells. Electron microscopy showed intermediate filaments, rare desmosomes and sparse microvilli. Morphological findings were consistent with a DMM, with a biphasic pattern in the pleura and an epithelial one in the peritoneum and tunica vaginalis. Although the possibility of a multicentric origin cannot be ruled out, clinical chronologic sequence suggests that the pleura was the primary involved site, followed by spread to peritoneum and tunica vaginalis.
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