Case 81

1. A 19-year-old female with a 7.6 cm ovarian mass.

1. What's your preferred diagnosis?

   A: Serous carcinoma

   B: Undifferentiated carcinoma

   C: SMARCA4 deficient uterine sarcoma

   D: Embryonal rhabdomyosarcoma

   E: Small cell carcinoma of the ovary

   
   

Answer

It's a not a fair question for anyone with just this morphology but the options are all possible differential diagnosis. This case showed a SMARCA4 (BRG1) loss. This tumor is characterized by small to large epithelioid cells with prominent nucleoli and brisk mitotic activity. It demonstrates a diffuse growth pattern of tightly packed cells, often arranged in nested or corded architecture with stromal hyalinization. Rhabdoid morphology, necrosis, and lymphovascular invasion are common features.

SMARCA4-deficient undifferentiated sarcoma (SDUS) is characterized by inactivating somatic mutations in SMARCA4, including missense, nonsense, frameshift, and splice site mutations, as well as whole-gene deletions. A germline SMARCA4 mutation has been reported in one patient.

SDUS is a chromosomally stable cancer and exhibits a distinct DNA methylation profile, which differentiates it from other SWI/SNF-deficient tumors, such as small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) and undifferentiated endometrial carcinoma.

Reference: https://www.pathologyoutlines.com/topic/uterusSMARCA4sarcoma.html

Case credit: https://qp-qp.91360.com/pc/109cfd8012f5a76913bee722c94d1b0e?userKey=&lang=en&cname=qpLib

Author: Wangpan Jackson Shi, MD