Mediastinal histoplasmosis: F-18 FDG PET and CT findings simulating malignant disease.

We describe the computed tomography and F-18 FDG PET findings of a patient with extensive mediastinal nodal enlargement resulting from histoplasmosis. This patient with known metastatic melanoma presenting for restaging was initially considered to have widespread mediastinal and cervical metastases on the basis of the imaging findings. Bronchoalveolar lavage fluid and transbronchial lymph node biopsy were consistent with histoplasmosis. The imaging findings improved after treatment with antifungal medication. A relatively small area of pulmonary involvement proved to be the clue in the imaging studies that the disease was inflammatory rather than neoplastic.