低级别浆液癌伴去分化

The pathogenesis of serous ovarian tumors has been extensively investigated, with a dualistic model dividing these cancers into 2 groups. Type I tumors, including lowgrade serous carcinoma, is characteristic for concurrent presence of borderline tumors,less atypical cytology, relatively indolent biologic behavior, and molecular aberrations related to the MAPK pathway with chromosomal stability. Meanwhile, type II tumors,such as high-grade serous carcinoma, are notable for no significant association with borderline tumors, higher grade cytology, more aggressive biologic behavior, and TP53 mutations along with chromosomal instability. We describe a case of morphologic low grade serous carcinoma with focally increased cytologic atypia arising in serous borderline tumors involving both ovaries, which demonstrated highly aggressive behavior despite several years of surgical and chemotherapeutic management. 

Each recurrent specimen contained more uniform higher grade morphology than what was seen in the original specimen. Immunohistochemical and molecular studies in both the

original tumor and the most recent recurrence demonstrate identical mutations in the MAPK genes, but with additional mutations in the latter, notably an acquisition of a variant of possible clinical significance in the SMARCA4 gene, which is associated with

dedifferentiation and aggressive biologic behavior. This case challenges our current and still evolving understanding of the pathogenesis, biologic behavior, and expected clinicaloutcome of low-grade serous ovarian carcinomas. It also underscores the need for further investigation into this complicated tumor.

Tumor morphology in original resection specimen. Morphology is shown on H&E. Low-grade serous carcinoma is appreciated in a
background of serous borderline tumor at low (A, 40×) and high (B, 200×) magnifications. Focal increased cytologic atypia is identified as well,
shown at low (C, 40×) and high (D, 200×) magnifications. Micropapillary architecture can be appreciated in (A) and (C).

Tumor morphology in most recent recurrence in transverse colon. Morphology is shown on H&E at magnifications of 20× (A); 40×
(B); 100× (C); and 200× (D). Abundant eosinophilic cytoplasm can be particularly appreciated in (D). The immunohistochemical expression of
BRG1/SMARCA1 is seen in (E) (100× magnification).