Clinical Challenges

Clinical Challenges - August 2016:
What's Your Diagnosis?

Publish date: August 12, 2016

What's Your Diagnosis?

BY SHAN-CHI YU, MD, CHIH-HORNG WU, MD, AND HSIN-YI HUANG, MD. Published previously in Gastroenterology (2012;143:1156, 1140).

A 53-year-old man with history of type 2 diabetes mellitus had an elevated serum creatinine level in the routine screening for diabetic nephropathy. He underwent renal ultrasonography, and abdominal masses were incidentally found.
Computed tomography showed multiple cystic lesions that have thin walls, internal septations, and liquids of different attenuation in the abdominal and pelvic cavities (Figures A and B).

The cystic lesions and appendix were resected under the clinical impression of pseudomyxoma peritonei.

There were multiple, thin-walled, cystic tumors containing clear fluid throughout the abdominal and pelvic cavities.

Histologic examination showed multilocular cystic lesions with fibrotic walls and proteinaceous content (Figure C).

The cysts were lined by a single layer of flattened or cuboidal cells, which were positive for calretinin (Figures D) and negative for CD31 (an endothelial marker). A carcinoid tumor was incidentally found at the appendix.


 

The diagnosis

We present a case of benign multicystic mesothelioma with extensive involvement of the abdominal and pelvic cavities in a male patient. Benign multicystic mesothelioma is a rare tumor most frequently localized to the pelvic peritoneal surface. Patients are usually women of reproductive age without a history of asbestos exposure. The gross appearance is typically multiple translucent membranous cysts that are grouped together to form a mass or discontinuously studding the peritoneal surface. Microscopically, the cystic spaces are lined by mesothelial cells expressing markers such as calretinin. The major differential diagnosis is cystic lymphangioma, in which cystic spaces are lined by endothelial cells. Preoperative diagnosis by fine-needle aspiration cytology has been described in the literature. Cytology shows monomorphous cells with mesothelial features in a clean background. 1 The disease course is usually indolent, but local recurrence after operative intervention is common. 2,3

References

1. Devaney, K., Kragel, P.J., Devaney, E.J. Fine-needle aspiration cytology of multicystic mesothelioma. Diagn Cytopathol. 1992 Jan;8:68-72 .

2. Ross, M.J., Welch, W.R., Scully, R.E. Multilocular peritoneal inclusion cysts (so-called cystic mesotheliomas). Cancer. 1989 Sep;64:1336-46 .

3. Weiss, S.W. Tavassoli, F.A. Multicystic mesothelioma (An analysis of pathologic findings and biologic behavior in 37 cases). Am J Surg Pathol. 1988 Oct;12:737-46 .

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