SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A member 4 (SMARCA4)-deficient tumors are rare and highly aggressive tumors characterized by a loss of SMARCA4 expression, and SMARCA4-deficient tumors in the adnexal area of the uterus are particularly rare. The present study describes the case of a 64-year-old woman who was admitted to Weifang People\'s Hospital (Weifang, China) with abdominal distension, and was observed to have a mass with ascites in the adnexal area of the uterus. Based on clinical, imaging and pathological findings, the patient was diagnosed with a SMARCA4-deficient adnexal tumor with ascites. Biopsy of the left and right adnexal lesions was performed, and the patient was administered chemotherapy. After one cycle of bevacizumab, sindilizumab and carboplatin, no further treatment was administered. After biopsy and chemotherapy, the abdominal distension was alleviated and the general condition of the patient was satisfactory. The patient was followed up and died 3 months after treatment. Notably, it is important to avoid misdiagnosing this tumor as other types of adnexal uterine tumors, and morphological and immunohistochemical features may be useful for diagnosing primary SMARCA4-deficient tumors in the adnexal area of the uterus.

Thoracic SMARCA4-deficient undifferentiated tumors (SMARCA4-UTs) are rare undifferentiated thoracic malignancies with poor prognosis. They predominantly affect young men who are heavy smokers. Recently, the category of SMARCA4-deficiency-related malignancy has been expanded to include extra-thoracic sites, such as the paranasal sinuses, gastrointestinal tract, ovary, and uterus. We report a rare case of SMARCA4-deficient tumors in the adrenal gland and small intestines. SMARCA4-deficient tumors should be included in the differential diagnosis when multiple large masses with heterogeneous contrast effect and strong accumulation are seen in cancers of unknown primary on 18F-fluorodeoxyglucose (FDG) positron emission tomography with computed tomography (PET/CT).

A new classification of SMARCA4-deficient tumors was proposed recently for thoracic malignancies, and the tumors have some histopathological characteristics similar to those of carcinosarcoma. We encountered a case of SMARCA4-deficient rectal carcinoma with a sarcomatoid component. A 46-year-old man presented to our hospital with a prolapsing anal mass. Colonoscopy revealed an irregular, nodular, and elevated lesion in the rectum, and the biopsy revealed a moderately differentiated adenocarcinoma. Abdominoperineal resection of the rectum was performed. A macroscopic image of the resected specimen showed a complex tumor 3.5 cm × 3 cm in size with a papillary protrusion and an irregular ulcerative lesion. Histopathological examination revealed that the tumor was composed of moderately/poorly differentiated adenocarcinoma and atypical spindle cells. The adenocarcinoma component was positive for epithelial markers (AE1/AE3 and carcinoembryonic antigen) and showed deletion of SMARCA2 and SMARCA4, while the spindle cells expressed mesenchymal markers (α-smooth muscle actin and vimentin). The pathological diagnosis was poorly differentiated adenocarcinoma with a sarcomatoid component, pT3N2bM0, stage IIIc. Although our case had histological characteristics of carcinosarcoma, immunostaining revealed a deficiency of SMARCA4. This case presented a SMARCA4-deficient colorectal carcinoma with a sarcomatoid component, which was histopathologically similar to carcinosarcoma.