Abstract
BACKGROUND: A sarcoid reaction is a phenomenon characterized by histologically proven granulomatous lesions without evidence of sarcoidosis. This pathology is a benign tumor itself, but several reports have described sarcoid reactions accompanying malignant tumors. Sarcoid reactions occur in various cancers, such as skin, lung, ovary, stomach, and breast cancers. However, only a few published reports have described sarcoid reactions in patients with colorectal cancer. CASE PRESENTATION: A 76-year-old woman underwent laparoscopic sigmoidectomy for sigmoid colon cancer. The postoperative follow-up computed tomography and 18-fluorodeoxyglucose positron emission tomography-computed tomography findings were suspicious for splenic metastasis of the sigmoid colon cancer. The patient then underwent laparoscopic splenectomy. Histopathological examination of the resected lymph nodes and spleen showed a non-caseating epithelioid cell granuloma. The patient was diagnosed with a sarcoid reaction. CONCLUSIONS: To our knowledge, this is the first report of a sarcoid reaction in the spleen and regional lymph nodes after colon cancer resection. The effect of a sarcoid reaction on the prognosis in patients with colorectal cancer has not been fully determined because of the small number of such cases. Further analyses involving a larger number of cases are necessary to evaluate the relationship between sarcoid reactions and prognosis in patients with colorectal cancer. We herein present an extremely rare case of a sarcoid reaction in the spleen and regional lymph nodes.