INTRAOPERATIVE CYTOLOGIC DIAGNOSIS OF GRANULOMAS - A RETROSPECTIVE STUDY OF 156 CASES

To avoid contamination of equipment and reduce risks of infection, int raoperative cytology (IOC) is a useful substitute to conventional froz en section in the diagnosis of infectious diseases. One of the various histomorphologic patterns of infections is the granuloma, which somet imes may be difficult to diagnose cytologically. In an attempt to asse ss accuracy and pitfalls of IOC in the diagnosis of granuloma, cases d iagnosed as granuloma on IOC or on permanent sections (PS) at George W ashington University Medical Center were collected for the period of S eptember 1990 to March 1996. Cyto-histologic correlation was performed . During that time, a diagnosis of granuloma in either the IOC or PS w as rendered in 156 of 5,901 IOC cases. IOC showed definite granuloma ( 87), suspicious for granuloma (23), and neither definite nor suspiciou s for granuloma in 46 cases. The latter group corresponded to neoplasm s (5) and benign conditions (41). Eighty-five cases were accurately di agnosed as definite granuloma by both IOC and PS. Fifty-seven cases di agnosed as granuloma by PS corresponded on IOC to suspicious for granu loma (21), benign smear (41), and neoplasms (5). Only two cases were i ncorrectly diagnosed as granuloma on IOC: a neoplasm and a case of fib rosis. Overall, four cases of neoplasms were interpreted as suspicious for granuloma (3) or definite granuloma (I) on IOC, and five cases of granulomas were misdiagnosed as neoplasms on IOC. Four Of these nine case were deferred for a PS diagnosis. IOC is a useful tool in the dia gnosis of granulomas with a sensitivity of 60% and specificity of 99% and positive and negative predictive values of 98% and 99%, respective ly. Rarely, neoplasms may be misdiagnosed as granulomas and vice versa . (C) 1998 Wiley-Liss, Inc.