A rare large cell variant of small-cell carcinoma of the ovary, hypercalcemic type in a postmenopausal woman: Case report.

RATIONALE: Small-cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is an extremely rare and aggressive ovarian malignancy associated with SMARCA4 mutation, accounting for less than 0.01% of ovarian tumors. It predominantly affects young females and is characterized by poor prognosis. Here, we report a unique case of SCCOHT with a special pathological classification of large cell variant type in a 59-year-old postmenopausal woman, an age that is rare for this disease. PATIENT CONCERNS: A 59-year-old female patient presented with lower abdominal pain. A hard and restricted mass was palpated at the back of the uterus during pelvic physical examination. MRI examination showed a huge solid mixed-signal mass shadow in the right adnexal area, with a size of 10 × 7 × 7 cm. DIAGNOSES: Postoperative histopathological and immunohistochemical analyses demonstrated abundant large cells under microscopic examination and a loss of BRG1 protein expression, leading to the diagnosis of large cell variant of SCCOHT in right ovary. Genetic testing confirmed a mutation in the SMARCA4 gene (exon 6, c.1103del p.[Q368Rfs*43]). INTERVENTIONS: The patient underwent pelvic tumor cytoreductive surgery and pelvic adhesion release surgery, and the implanted lesions in the pelvic cavity were resected during the operation. OUTCOMES: The patient underwent extensive surgical resection and completed 6 cycles of TC chemotherapy (paclitaxel + carboplatin). Despite the postoperative pathological stage reached Stage II, during the 18-month follow-up after the operation, no evidence of tumor progression or recurrence was observed. LESSONS: SCCOHT is a highly malignant tumor associated with a generally poor prognosis, particularly for tumors at stage II or higher. Nevertheless, the favorable prognosis observed in this case suggests that the traditional understanding may require reevaluation. Whether there is a correlation between the age of onset of SCCOHT and the prognosis remains to be elucidated through systematic clinical research in the future.