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Diagnostics Histology, Clinical care, Microscopy and imaging

Case of the Month

Ovarian Mass

The hematoxylin-eosin-stained slides shown here were prepared from a 20 cm mass, partially cystic and partially solid, that was removed from the right ovary of a 59-year-old female. Immunohistochemically, the tumor was positive for napsin-A and PAX8, but negative for p53 and WT1.

What is the most likely diagnosis?

A. High-grade serous carcinoma

B. Clear cell carcinoma

C. Mucinous cystadenocarcinoma

D. Yolk sac tumor

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We will reveal the answer in next month’s issue!

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Answer to last month’s Case of the Month…

C. Kaposi sarcoma.

This tumor is composed of nodules of monomorphic spindle cells arranged in fascicles, consistent with the diagnosis of Kaposi sarcoma. Tumor cells form mitotic division figures and include rare entrapped inflammatory cells and erythrocytes. The expression of HHV-8 confirmed the diagnosis, excluding other vascular neoplasms listed in the differential diagnosis.

This is the classic variant of Kaposi sarcoma, which has a predilection for the skin on the legs of elderly men. Angiosarcoma favors the face and scalp and is composed of widely infiltrative, hyperchromatic endothelial cells that form crack-like vascular spaces and are negative for HHV-8. 

The present case was biopsied with the presumptive diagnosis of angiosarcoma.  It can be tempting to “copy and paste” a previous pathology or clinical diagnosis, but to us, the morphology of the present tumor did not fit the existing diagnosis. With some additional effort, we were able to come to the correct diagnosis. The message we repeat daily to our residents is: every case should be weighed and measured on its own merits. If the findings are inconsistent with a pre-existing diagnosis, it is upon the pathologist to consider and investigate alternative explanations.

Submitted by Garth Fraga, The University of Kansas, Kansas City, USA.


  1. Z Marušić, SD Billings, “Histopathology of spindle cell vascular tumors”, Surg Pathol Clin, 10, 345–366 (2017). PMID: 28477885.
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