Case 107

A 78-year-old female with a 7.5 cm ovarian mass and here is the fluid cytology:

1. What's your morphology impression?

   A: Benign, favor mesothelial origin

   B: Benign, endometriosis

   C: Malignant, high grade serous carcinoma

   D: Malignant, clear cell carcinoma

Answer

The correct answer is C. Patient's history of ovarian cancer is noted. Cell block demonstrates rare clusters of malignant cells. Tumor cells are positive for Claudin-4, MOC31, PAX8, and are predominantly negative for calretinin and CK5/6. They exhibit a P53 null phenotype which is consistent with high grade serous carcinoma. Please corrolate clinically as the number of tumor cells are very scant. Block for ancillary testing (tumor percentage): Cell block ~1%

Case credit: UCSD pathology

Author: Wangpan Jackson Shi, MD