Sarcoidosis is a systemic chronic granulomatous disease. It mostly involves the lungs and hilar lymph nodes and produces epithelioid granulomas. Granulomatous (sarcoid) reaction is known to be associated with malignancies; however, it is uncommonly seen with colon carcinomas. Furthermore, systemic sarcoidosis following cancer diagnosis is less commonly seen. To the best of our knowledge, cutaneous sarcoidosis related with an underlying colon carcinoma has not been reported previously in the literature. In this report, we present a very rare case with sarcoidosis development after resection of sigmoid adenocarcinoma, presenting with multiorgan involvement including the skin, eye, joints, and lymph nodes. 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG-PET/CT) images showed the skin, lung, spleen, mediastinal, and hilar lymph node involvement. Histopathological examination of skin lesions demonstrated granulomatous dermatitis. This case demonstrates that sarcoidosis can cause intensely FDG-avid lesions on 18F-FDG-PET/CT scans, mimicking metastasis in colon cancer patients. Histopathological evaluation is essential for confirming the diagnosis. 18F-FDG-PET/CT scan provides important information for evaluation of disease extension, progression, and clinical follow-up.
Keywords: Colonic adenocarcinoma; granulomatous dermatitis; sarcoidosis.