After several days in the hospital the rash began to fade, but the
low-grade fever, myalgia, arthralgia, and muscle weakness persisted.
Bronchoscopy was unrevealing, and subsequent transthoracic needle
aspiration was nondiagnostic. Concern regarding malignancy prompted
surgical exploration. The results of testing an intraoperative frozen
section were inconclusive, and a left upper lobectomy was performed.
Gross examination of the surgical specimen revealed a mass 3-cm in
diameter that, on microscopic examination, was composed of spindle
cells, the presence of which is consistent with IPT (Fig 2
). Immunohistochemical staining demonstrated that the bulk of these
cells were histiocytes. These findings confirmed the diagnosis of IPT,
fibrous histiocytoma type.