RESUMEN
Langerhan Cell Histiocytosis (LCH) is a disorder in which cells with a phenotype similar to that of epidermal langerhans cells cause tissue damage possibly through excessive cytokine production. The clinical spectrum of the disease is wide. We are reporting a case of LCH who presented with prolonged pyrexia and a clinically benign bony swelling of mandible of long duration, which was otherwise ignored as being unrelated. The biopsy from the swelling confirmed the diagnosis of LCH. Another biopsy from lower end of tibia where he had pain also demonstrated typical findings. There was no evidence of other system involvement. There was good remission of the swellings and the symptoms with steroid alone initially but later relapsed and is now on treatment as per LCH III protocol. The case is being reported for its rarity and for the unusual presentation as PUO.