Small-Cell Carcinoma of the Ovary of Hypercalcemic Type (Malignant Rhabdoid Tumor of the Ovary): A Review with Recent Developments on Pathogenesis.

Small-cell carcinoma of the ovary of hypercalcemic type (SCCOHT) is a highly malignant and aggressive tumor and is the most common undifferentiated ovarian malignancy to occur in women younger than 40. SCCOHT is characterized by deleterious germline or somatic mutations in SMARCA4. Given the striking morphologic and molecular similarities between SCCOHT and atypical teratoid/malignant rhabdoid tumor, we propose this should be reflected in a nomenclature change and that SCCOHT be renamed malignant rhabdoid tumor of the ovary. SMARCA4 (BRG1) immunohistochemistry is useful in diagnosis because there is loss of nuclear immunoreactivity in SCCOHT but retention of staining in mimics.