Clinicopathological Characteristics of Small Cell Carcinoma of the Ovary, Hypercalcemic Type – a case Series

Abstract Introduction/Objective Small cell carcinoma of the ovary hypercalcemic type (SCCOHT) is a rare (<0.01%) and aggressive ovarian tumor primarily affecting young women (median of approximately 24 years), characterized by rapid growth, early metastasis, and association with hypercalcemia in two-thirds of cases. The diagnosis of SCCOHT is challenging due to its rarity and lack of specific clinical symptoms or biomarkers. Our study aims to delineate the clinicopathologic characteristics of SCCOHT based on our case series and add to the existing knowledge. Methods/Case Report A retrospective review of University of Pennsylvania Health system pathology database was conducted from 2012 to 2024. Our study identified four patients diagnosed with SCCOHT. Clinical information and histopathologic characteristics were reviewed. Results (if a Case Study enter NA) Among the four patients identified, the median age was 24 years, with a median tumor size of 14.5 cm, and all patients presented with weight loss, abdomen bloating, and elevated CA125 levels. Notably, two patients exhibited hypercalcemia, while one initially presented with normal calcium levels but developed hypercalcemia during disease recurrence. One patient maintained normal calcium levels throughout. Surgical intervention involved bilateral salpingo-oophorectomy in all cases, with pathological staging revealing two patients at pT1a, one at pT1c, and one at pT3c. Histopathological analysis consistently revealed similar morphology, including solid and cystic necrotic neoplasms with diffuse growth or nests/cords of undifferentiated small cells, which displaying vesicular chromatin and prominent nucleoli. Immunohistochemical staining demonstrated loss of BRG1 (SMARCA4) expression in two patients and diffuse positivity for WT1 in all patietns, while negative for cytokeratin, germ cell markers, and melanocytic markers. Genetic test revealed SMARCA4 mutation (p.E 717*, c.3169-1G>A) in one patient. Conclusion Small cell carcinoma of the ovary, hypercalcemic type, presents a diagnostic and therapeutic challenge due to its rarity and aggressive nature. Adequate treatment options are currently limited, highlighting the critical need for further research and development of targeted therapies in SCCOHT. Testing for mutations in the SMARCA4 gene is essential for accurate diagnosis of SCCOHT and may uncover new avenues for treatment and management strategies.