A difficult diagnosis: acute histoplasmosis.

A 43-year-old male with deceased donor kidney transplantation presented with fever of unknown etiology and underwent an extensive workup. The diagnosis of histoplasmosis was made after biopsy of a positron emission tomography-positive subcarinal lymph node showed non-caseating granulomas with a positive stain for yeast. The diagnosis was confirmed when fevers remitted with initiation of appropriate anti-fungal therapy.