Inflammatory pseudotumor of lymph nodes presenting as pyrexia of unknown origin.

Inflammatory pseudotumor (IPT) is an uncommon benign disorder characterized by proliferation of spindle cells, inflammatory cells, and small vessels. The IPT of lymph nodes is a rare cause of lymphadenopathy that usually affects one or two nodal groups. We describe a 27-year-old male presenting with generalized lymphadenopathy, hepatosplenomegaly and fever for 1 year. Histologic examination of lymph node revealed few remnant lymphoid aggregates with marked sclerosis and numerous anastomosing blood vessels in lymph node parenchyma. Interspersed in between the fibrotic bands was a polymorphic infiltrate composed of lymphocytes, plasma cells, eosinophils, and immunoblasts. Also, many histiocytes, multinucleated giant cells some being Langhan's type and at places forming ill-defined granulomas were observed. The presence of granulomas and Langhan's type of giant cells can lead to a misdiagnosis of tuberculosis as was also done in the present case. It is thus not only important to be aware of this rare benign pathologic entity while dealing with a case of lymphadenopathy, but also consider it in the differential diagnosis of granulomatous disease.