“Signet‐ring” cells—A caveat in the diagnosis of a diffuse peritoneal mesothelioma occurring in a lady presenting with recurrent ascites: An unusual case report

Abstract

A diffuse peritoneal mesothelioma is a rare tumor. Exfoliative cytology forms the first step in the diagnosis of mesothelioma, since most of these cases presented with effusion. Despite well established cytomorphological features, a challenge exists in differentiating mesothelial cells, including reactive and malignant types from carcinoma cells and macrophages. Presence of "signet-ring" cells increases the diagnostic challenge as these can be forms of benign and malignant cells. Ancillary techniques like immunohistochemical (IHC) markers and ultrastructural analysis form useful adjunct in substantiating exact diagnosis. We report an unusual case study of a diffuse peritoneal mesothelioma in a 57-years-old lady, with no history of asbestos exposure, presenting with recurrent ascites, diagnosed on ascitic fluid cytology and on histology as an adenocarcinoma, based upon the presence of "signet-ring" cells. On review, clinicopathological correlation with IHC was helpful in forming correct diagnosis.

Mesothelioma with signet-ring cell features: report of 23 cases

“…33 Most epithelioid mesotheliomas exhibit a tubulopapillary, adenomatoid, or solid pattern; however, in rare instances, they may present other histologic patterns, including deciduoid, [36][37][38] clear cell, 39,40 adenoid cystic, 34 pleomorphic, 41,42 small cell, 43,44 rhabdoid, 45 glomeruloid, 46 oncocytoid, 47 and signet-ring cell. 31,35 Although the finding of an occasional signet-ring cell is not rare in mesotheliomas, the presence of large areas primarily composed of this type of cell is relatively uncommon, as is demonstrated by the fact that only a very limited number of publications on mesotheliomas with signet-ring-like features have been published. In a review of the literature, I was able to find only two publications that focused primarily on signet-ring cell mesotheliomas, both of which were case reports and both of these cases were peritoneal mesotheliomas.…”

“…In a review of the literature, I was able to find only two publications that focused primarily on signet-ring cell mesotheliomas, both of which were case reports and both of these cases were peritoneal mesotheliomas. 31,35 One report was the case of a 57-year-old woman with no history of asbestos exposure who presented with recurrent ascites that was initially diagnosed as a carcinoma because of the presence of signet-ring cells in the cytologic preparations. 35 The second was the case of a 59-year-old man with a 30-year history of heavy asbestos exposure who presented with ascites containing malignant cells whose precise type could not be determined.…”

“…31,35 One report was the case of a 57-year-old woman with no history of asbestos exposure who presented with recurrent ascites that was initially diagnosed as a carcinoma because of the presence of signet-ring cells in the cytologic preparations. 35 The second was the case of a 59-year-old man with a 30-year history of heavy asbestos exposure who presented with ascites containing malignant cells whose precise type could not be determined. 31 As ultrasound studies revealed thickening of the gastric wall, the possibility of linitis plastica was raised.…”

“…32 Even though mesotheliomas with signet-ring features are often mentioned in major publications and review articles on the pathology of mesotheliomas, 1,33,34 to my knowledge, only two case reports in which the primary focus was on this variant of epithelioid mesothelioma have been published. 31,35 Given that a detailed investigation of a series of signetring cell mesotheliomas has yet to be published, the study of 23 such cases was undertaken and the results are herein reported. The value of both immunohistochemistry and electron microscopy in assisting in distinguishing these tumors from signet-ring cell adenocarcinomas of the lung, several cases of which are included for comparison purposes, is also discussed.…”

Pleomorphic mesothelioma: report of 10 cases

“…Based on their light microscopic features, the 2004 WHO Classification defines four major histologic subtypes of diffuse malignant mesothelioma: epithelioid, sarcomatoid, mixed epithelioid and sarcomatoid (biphasic), and desmoplastic. 1 Although epithelioid mesotheliomas most frequently present a tubulopapillary, adenomatoid (microglandular) or solid pattern, on rare occasions, they may present other histologic patterns, including deciduoid, [2][3][4] clear cell, 5,6 adenoid cystic, 7 pleomorphic, 8,9 small cell, 10,11 rhabdoid, 12 glomeruloid, 13 signet-ring cell 14,15 and oncocytoid. 16 Some of these patterns, such as the pleomorphic, however, have not been well defined.…”