Pulmonary nocardiosis in fine-needle aspiration cytology smears: Report of four cases.

Nocardia has been recognized as a significant opportunistic pathogen in organ transplant patients; however, it is an uncommon pathogen in immunocompetent patients. It may mimic other infectious diseases both clinically and radiologically. We report four cases of pulmonary nocardiosis in three immunocompromised and one immunocompetent patients on fine-needle aspiration cytology (FNAC). Two patients presented with lung consolidation while two had cavitatory lesions. FNAC smears showed inflammatory cells composed of polymorphs and histiocytes along with necrosis. Occasional epithelioid cell granuloma was seen in one case. Modified Ziehl-Neelsen (ZN) stain was performed which highlighted long slender filamentous branching organisms conforming to the morphology of Nocardia. Thus, a suspicion for nocardiosis should be kept while assessing cytologic material especially in immunocompromised individuals. The diagnosis can be confirmed by special stains and culture studies; however, a high index of clinical suspicion is required so that appropriate culture media can be used for high diagnostic yield. FNAC is of help in providing immediate and accurate diagnosis of nocardiosis, thus helping in appropriate medical management.