Nodal mycobacterial spindle cell pseudotumor: A diagnostic pitfall

Inflammatory pseudotumor (IPT) is a rare benign mass forming lesion that has been reported in virtually every organ, and can closely mimic spindle cell neoplasms. Mycobacterial spindle cell pseudotumor (MSP) represents a small proportion of IPT of the lymph node, which occur in immunocompromised patients, posing a diagnostic challenge. We report three cases of MSP involving two AIDS patients who presented with generalized lymphadenopathy, and one immunosuppressed patient with a mediastinal mass. Biopsy in these cases revealed effaced architecture replaced by proliferating fibrohistiocytic spindle cells, fibrosis and polymorphic inflammatory infiltrate. Inflammatory pseudotumors and other spindle cell neoplasms of the lymph node can show overlapping morphologic features, resulting in diagnostic confusion. A differential diagnosis of Mycobacterial spindle cell pseudotumor should be kept in mind when approaching localized or generalized lymphadenopathy in an immunocompromised patient.