Image Description
The differential diagnosis of adult granulosa cell tumor (GCT) includes the following: cellular fibroma/thecoma, endometrial stromal sarcoma, undifferentiated carcinoma, high-grade serous carcinoma, small cell carcinoma - hypercalcemic type, endometrioid carcinoma, insular carcinoid tumor, sex cord tumor with annular tubules, gonadoblastoma, large solitary luteinized follicle cyst of pregnancy (for cystic adult GCT), and metastases (melanoma, lobular breast carcinoma).
The differentiating features of each of these entities are discussed over the next several images.
Cellular Fibroma/Thecoma: Diffuse fibromatous areas in adult GCT may resemble cellular fibroma or thecoma. Adult GCT will show areas with typical granulosa cell differentiation elsewhere in the tumor and grooved nuclei at higher magnification. With reticulin stain, adult GCT shows reticulin fibrils around entire nests of cells rather than around individual cells (see next image). Cellular fibromas have storiform growth in a collagenous background and show hyaline plaques. Any sex cord-stromal elements in fibromas, by definition, make up < 10% of the tumor. Fibromas may be positive for FOXL2 but lack the mutation.
The differentiating features of each of these entities are discussed over the next several images.
Cellular Fibroma/Thecoma: Diffuse fibromatous areas in adult GCT may resemble cellular fibroma or thecoma. Adult GCT will show areas with typical granulosa cell differentiation elsewhere in the tumor and grooved nuclei at higher magnification. With reticulin stain, adult GCT shows reticulin fibrils around entire nests of cells rather than around individual cells (see next image). Cellular fibromas have storiform growth in a collagenous background and show hyaline plaques. Any sex cord-stromal elements in fibromas, by definition, make up < 10% of the tumor. Fibromas may be positive for FOXL2 but lack the mutation.