Deciduoid peritoneal mesothelioma. A report of the cytological appearances

Mesothelioma

Mesothelioma arises from the surface serosal cells lining the pleural, peritoneal, and pericardial cavities. It has three variants including: epithelioid, sarcomatous/desmoplastic, and biphasic types. Mesothelioma cells, predominantly of the epithelioid type, can shed into effusions as sheets, clusters/ morulae, papillae, or single cells. The challenges to cytologic diagnosis of mesothelioma are two-fold: 1. distinguishing mesothelial cells from metastatic malignant (most commonly carcinoma) cells; 2. distinguishing reactive mesothelial from mesothelioma cells. Immunocytochemistry is a helpful aid to cytologic evaluation for the former. The distinction of reactive mesothelial cells from mesothelioma can be more difficult, as there is considerable overlap in their appearances in effusion specimens. Recently developed ancillary molecular and genetic tests are proving to be useful in confirming the diagnosis of malignant mesothelioma in cytology specimens.

Malignant Deciduoid Mesothelioma: case presentation of an exceptional variant and review of the literature

BACKGROUND

Malignant Deciduoid Mesothelioma (MDM) is an extremely rare variant of epithelioid mesothelioma. It was first described in young females, in the peritoneum, and its relation with asbestos was not well defined. Later reports, have shown that this variant may also occur in the pleura, the pericardium and the tunica vaginalis of elderly people, who had been exposed to asbestos.

CASE PRESENTATION

We report a case of malignant deciduoid mesothelioma that occurred in the peritoneal cavity, and the omentum of a 35-year-old woman. The patient had never been exposed to asbestos.

CONCLUSIONS

Through this observation, we describe clinical, histopathological, and immunohistochemical findings of deciduoid mesothelioma, and review the literature reports.

Deciduoid mesothelioma: report of 21 cases with review of the literature

Deciduoid mesothelioma is a rare variant of epithelioid mesothelioma that was initially considered to occur exclusively in the peritoneum of young women who had no history of asbestos exposure and to be characterized by an aggressive clinical course, but it was later demonstrated that this tumor could also occur in the pleura of older men and women who had been exposed to asbestos. Some subsequent studies have also indicated that the clinical course is no different from that of conventional epithelioid mesothelioma. Herein are reported 21 cases of deciduoid mesothelioma that were investigated using a large panel of immunohistochemical markers, 9 of which were also studied by electron microscopy. Fifteen of the patients were male and 6 were female (mean age, 60 years). Seventeen of the cases originated in the pleura and four in the peritoneum. Histologically, all of the cases were composed of large, polygonal or ovoid cells with well-defined cell borders, dense eosinophilic cytoplasm, and single or multiple nuclei. In some cases, the cells exhibited a wide variation in their size and shape, frequent loss of cell cohesion, marked nuclear atypia, and high mitotic activity (>5 per 10 HPF); whereas, in others, the cells were more cohesive, less pleomorphic, and the mitotic activity low. As the survival of patients in the first group of cases was shorter (mean, 7 months), when compared with that of the latter (mean, 23 months), it is concluded that the differences in prognosis reported in deciduoid mesothelioma are due to the existence of a high-grade subgroup that presents highly aggressive clinical behavior. Therefore, when a high-grade deciduoid mesothelioma is present, it should be reported as it can significantly affect prognosis and treatment. The use of immunohistochemistry and electron microscopy in assisting in the differential diagnosis of deciduoid mesothelioma is also discussed.

Metastasis of a pleural mesothelioma to a hyperplastic stomach polyp: an increase of vimentin expression is seen during a gain in deciduoid morphology

Deciduoid mesothelioma is a rare variant of the epithelioid histotype spectrum, resembling decidua of gravid uterus. It is found in the peritoneum of young women, but also in the pleura of elderly people. Histotype plasticity from epithelioid to sarcomatoid mesothelioma may be considered as epithelial-mesenchymal transition (EMT). A full autopsy was performed and mesothelioma infiltrates were analysed by immunohistochemistry. The metastasis of an epithelioid pleural mesothelioma to a hyperplastic polyp of the stomach is presented in this autopsy case. Deciduoid morphology increased during tumour progression and metastasis. The increase in eosinophilic cytoplasm correlated with the upregulation of the intermediate filament vimentin. High expression of vimentin was found in both central and superficial periglandular regions of the polyp. High vimentin expression also can occur in epithelioid rather than sarcomatoid differentiation. Thus, although vimentin is considered to be the major EMT marker, additional pathways must regulate its expression.

Primary malignant deciduoid peritoneal mesothelioma: a report of the cytohistological and immunohistochemical appearances

Malignant deciduoid mesothelioma (MDM) is a rare variant of epithelioid mesothelioma. This type of tumor might be associated with the asbestos exposure and carries a poor prognosis in general. MDM was first described by Nascimento et al. in 1994 in a peritoneal lesion of a young woman. And its diagnosis is frequently mistaken with florid mesothelial hyperplasia and peritoneal deciduosis. There are 44 MDM cases reported in the literature up today. A 59-year-old woman patient referred to our clinic was identified with an abdominal mass. Computed tomography of whole abdomen of the patient showed a mass with the widest transverse dimension of 65 × 60 mm at abdominal bifurcation in the mesenteric region. The patient was diagnosed with MDM after the cytopathological examination of the fine needle aspiration biopsy performed from the mass. Consequently, she received a total mass excision and right hemicolectomy under general anesthesia. The cytomorphological appearance of the ascitic fluid is detailed for the first time by Gillespie et al. and is described only in two manuscripts. In the present study, we aimed to report a case of a 59-year-old woman since she was diagnosed with MDM and because her cytological findings were further supported by histomorphological and immunohistochemical evaluations of the operation material obtained from the patient.

Comparative genomic hybridisation in malignant deciduoid mesothelioma

BACKGROUND

Malignant deciduoid mesothelioma is a rare variant of epithelioid mesothelioma. This tumour generally has poor prognosis, and can be asbestos related.

AIM

To identify peculiar genetic changes responsible for critical phases in pathogenesis of malignant deciduoid mesothelioma and their prognostic relevance.

METHODS

Comparative genomic hybridisation was carried out in six cases of malignant pleural deciduoid mesothelioma, four sporadic and two familial. All cases were found to be asbestos related. Four patients died during follow-up and the mean survival was 29.5 (SD 14.2, range 12-43) months.

RESULTS

Genetic abnormalities were found in all the tumour tissues, the most frequent being chromosomal gains at 1p, 12q, 17, 8q, 19 and 20 and losses at 13q, 6q and 9p. Survival was found to be longer in those patients who presented a smaller number of losses (< or =2) in the tumorous chromosomes.

CONCLUSIONS

Although numerous genetic changes are presented by deciduoid mesotheliomas, certain chromosomal regions are preferentially affected. The clinical outcome for this mesothelioma subtype is predicted by the number of losses.

Deciduoid mesothelioma in the pelvic cavity

A very rare case of deciduoid mesothelioma in the pelvic cavity is presented. A 24-year-old woman (gestational stage: 28 weeks and 6 days) was admitted because of a tumor mass in the abdominal cavity. A well-circumscribed and fibrously encapsulated tumor mass was revealed in the Douglas cavity. Histologically, tumor cells were arranged in a solid sheet with deciduoid appearance and showed partial glandular and papillary structures. The tumor cells contained PAS positive and diastase-digested granules in the cytoplasm as well as alcian-blue positive and hyaluronidase-digested substances in the stroma. The cellularity of the tumor cells was moderate and mitoses were rare. There was partial tumor necrosis and tumor cells had infiltrated through the fibrous capsule. Immunohistochemically, the tumor cells were reactive for pancytokeratin, cytokeratin5/6, vimentin, HBME-1, calretinin and thrombomodulin. Ultrastructurally, numerous, long microvilli, tonofilaments and desmosome junctions could be seen. Consequently, this case was diagnosed as deciduoid mesothelioma and 2 years and 4 months after operation, the patient's clinical course has been good. This case is considered to be the first reported in Japan.

Primary epithelial malignant mesothelioma of the pericardium with deciduoid features: cytohistologic and immunohistochemical study

Malignant mesothelioma with deciduoid features (MMWDF) is a recently characterized morphologic variant of epithelioid malignant mesothelioma, which frequently is misdiagnosed as peritoneal deciduosis or florid mesothelial hyperplasia. We report on the cytological, histological, immunohistochemical, and autopsy findings of a case of MMWDF arising in the pericardium of a 71-yr-old female patient. Cytology showed large, polygonal to round cells with pale to bright, eosinophilic cytoplasm, occasionally showing xantomatous pattern, containing a pleomorphic and vesicular nucleus with a single prominent nucleolus. Autopsy examination showed a neoplasm encasing the heart and great vessels. No other primary neoplasm was found. The histological analysis disclosed the typical features of MMWDF. Immunohistochemistry showed diffuse immunoreactivity for cytokeratin MNF116, HBME-1, and calretinin in the neoplastic cells, as well as focal positivity for epithelial membrane antigen positivity in a brush border-like pattern. All other markers were negative. We would like to stress that pathologists must be aware of the cytological and histological features of this rare variant of epithelioid malignant mesothelioma in order to avoid a misdiagnosis of a benign process or a metastatic malignancy.