Sarcoid reaction: a rare occurrence associated to colon adenocarcinoma (case report and literature review).

Granulomatous reactions are related to infectious and non infectious diseases, but more rarely, granulomas may occur in association to malignancies. The presence of sarcoid-like granulomas in lymph nodes draining malignant tumors is an uncommon but well known occurrence. However, their presence in the stroma of malignant tumors is much rarer. We have only found two previous cases reported in the Japanese and English literature. In this study we report a well differentiated adenocarcinoma of the right colon associated to a stromal granulomatous sarcoid-like reaction. Lymph nodes were not involved. The patient had a clinical history of tuberculosis treated 15 years ago, but there was no clinical, histomorphological, immunohistochemical or molecular evidence of disease at the moment of these findings. We have reviewed the literature to find the keys and the diagnostic challenges posed by granulomatous sarcoid-like reaction occurring in lymph nodes draining malignant neoplasms, peritumoral stroma and in other organs far from the primary tumor. The diagnosis of granulomatous sarcoid-like reactions associated to malignancies can be challenging and it can only be made after ruling out specific infectious and non infectious causes of granulomatous inflammation. The mechanisms involved in granuloma formation, their relationship with demographic and histopathological features, their possible association with autoimmune disorders, their cytokine profile and, more importantly, their prognostic significance in each type of tumor are still unclear and require studies with larger number of patients.