Epithelioid cell granulomatous response of Waldeyer's ring among Japanese : a clinicopathological and immunohistochemical study of 16 cases.

The tonsils are uncommonly affected by granulomatous inflammation. This study attempted to clarify the clinicopathological and immunohistochemical findings and presence or absence of Epstein-Barr virus (EBV) in tonsilar granulomatous inflammation. A total of 537 consecutive specimens from tonsillectomies performed at Dokkyo University School of Medicine between 1999 and March 2012 were reexamined. Using formalin-fixed, paraffin-embedded sections, histological, immunohistochemical, and in situ hybridization (ISH) studies were performed. Epithelioid granulomas (EPGs) were identified in the tonsils in 16 (3.0%) cases. There were 8 males and 8 females, aged 4 to 57 years (mean, 23). In 11 patients, EPGs were located in the germinal center (GC), whereas they were located in the interfollicular area as well as GC in the remaining 5 cases. Three types of EPG have been delineated : (i) poorly demarcated small epithelioid cell granulomas (n = 6) ; (ii) well-demarcated non-caseating sarcoid-like granulomas (n = 5) ; and (iii) EPGs within GC showing suppurations at the center (n = 5). An ISH study demonstrated EBV-encoded small RNA (EBER)(+) cells in 4 lesions. The present study demonstrated that the majority of EPGs were located in the GC and tonsilar EPGs showed histological variation.