RELAPSING NODULAR LESIONS IN THE COURSE OF ADULT PULMONARY LANGERHANSCELL HISTIOCYTOSIS

In most patients with pulmonary Langerhans cell histiocytosis (LCH), c linical and radiological abnormalities initially either stabilize or r egress, often without treatment. Little information is available, howe ver, concerning the subsequent evolution of disease in patients who in itially follow a benign course. We describe four patients with biopsy- confirmed pulmonary LCH whose initial course was characterized by regr ession of parenchymal nodular lesions, but who subsequently developed one or more episodes of active disease 7 mo to 7.5 yr after their init ial presentation. In each case, the subsequent episodes of active dise ase were characterized by the reappearance or marked increase in nodul ar radiographic abnormalities, whose presence was confirmed by high-re solution computed tomography (HRCT). Thus, initial regression of nodul ar lesions in pulmonary LCH does not preclude the reappearance of one or more episodes of active disease, and may have important consequence s on the long-term prognosis of these patients.