Fine needle aspiration cytology of mycobacterial spindle cell pseudotumor. A case report

We report a case of mycobacterial spindle cell pseudotumor (MSP) in a lymph node from an acquired immunodeficiency syndrome patient diagnosed by fine needle aspiration (FNA). The FNA cytology was characterized by spindle cell proliferation without the typical foamy histiocytes usually seen in mycobacterial infections and mimicked a mesenchymal neoplasm, particularly Kaposi's sarcoma. This case illustrates the importance of including MSP in the differential diagnosis of lymph node FNAs from immunocompromised patients, particularly those that show spindle cell proliferation suspicious for Kaposi's sarcoma or another mesenchymal neoplasm.