CT imaging characteristics of ovarian small cell carcinoma: correlation with clinicopathology and prognosis

Small cell carcinoma of the ovary (SCCO) is a rare, highly aggressive malignancy comprising pulmonary type (SCCOPT) and hypercalcemic type (SCCOHT). Clinical presentations are nonspecific, and CT features remain poorly defined. We aimed to characterize CT findings of SCCO, compare subtypes, and evaluate associations with pathology and outcomes. We retrospectively analyzed 42 patients with pathologically confirmed SCCO (8 institutional cases and 34 literature-derived cases). Clinical, pathological, and follow-up data were collected. Pre-treatment contrast-enhanced CT images were independently reviewed by two senior radiologists. Imaging features were correlated with immunohistochemical markers and survival outcomes. The cohort included 22 SCCOPT and 20 SCCOHT cases. Compared with SCCOPT, SCCOHT patients were younger (25.5 vs. 54.0 years, P < 0.0001), had larger tumors (15.0 vs. 11.1 cm, p = 0.039), and more frequently had hypercalcemia (55.0% vs. 0%, p = 0.0002). On CT, SCCOPT commonly presented as irregular (63.6%), ill-defined (59.1%) solid or mixed masses with moderate-to-marked enhancement and frequent metastases, whereas SCCOHT typically appeared as large unilateral, well-circumscribed cystic–solid tumors with mild-to-moderate peripheral enhancement and central necrosis, often mimicking benign lesions. BRG1 loss was associated with lower enhancement and reduced invasiveness (r = − 0.64 to − 0.41, p < 0.05), while high Ki-67 expression correlated with irregular morphology, marked enhancement, and metastasis (r = 0.33–0.47, p < 0.05). In SCCOPT, lower chromogranin A expression correlated with ill-defined margins (r = − 0.45, p = 0.035). Median overall survival remained poor (14.4 months for SCCOPT vs. 11.0 months for SCCOHT). In multivariable Cox analysis, irregular morphology (HR = 3.75, p = 0.03) and bowel invasion (HR = 3.13, p = 0.03) independently predicted worse overall survival. CT features differ between SCCOPT and SCCOHT and show meaningful associations with immunohistochemical markers and outcomes. Integrating imaging with molecular pathology may aid preoperative risk stratification and prognostic assessment in this rare malignancy.