Clinical significance of sarcoid-like reaction in lymph nodes of gastric cancer patients

Background Although granulomatous formation (sarcoid-like reaction [SR]) similar to sarcoidosis occasionally occurs in regional lymph nodes of malignant tumors, the pathological significance of SR is unknown. We aimed to elucidate the clinicopathological significance and prognostic relevance of SR in gastric cancer. Methods We evaluated 391 patients who underwent curative gastrectomy for gastric cancer between 2007 and 2016 at our hospital. The patients were divided into two groups according to presence of SR in lymph nodes, and clinicopathological factors and prognosis were compared between the two groups. Results SR was found in 67 (17.1%) of the 391 patients, and 332 (3.3%) of 10,149 lymph nodes examined. Regarding clinicopathological factors, SR-positive group showed significantly higher average age (p < 0.01) and numbers of differentiated tumors than SR-negative group (p < 0.05). Three-year overall survival rate in elderly patients aged >= 75 years was significantly more favorable in SR-positive group (n = 27, 85.2%) versus SR-negative group (n = 97, 63.4%) (p < 0.05). Immunohistochemical studies showed the predominant presence of CD68-positive macrophages for SR, with CD4/CD8-positive T cells and interleukin-10 also positive. Conclusion The presence of SR in gastric cancer is frequent in elderly patients and might be a favorable indicator of prognosis. SR is suggested to reflect immune activation in the host.