{Reference Type}: Case Reports
{Title}: SMARCA4-deficient rectal carcinoma with a sarcomatoid component: a case report.
{Author}: Meda Y;Miyake H;Nagai H;Yoshioka Y;Yuasa N;Kiriyama A;Fujino M;Meda Y;Miyake H;Nagai H;Yoshioka Y;Yuasa N;Kiriyama A;Fujino M;
{Journal}: Clin J Gastroenterol
{Volume}: 15
{Issue}: 2
{Year}: Apr 2022
暂无{DOI}: 10.1007/s12328-022-01602-y
{Abstract}: 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.