We present a 22-year old male patient previously treated with radiotherapy and surgery at the age of 7 for an undefined suprachiasmatic mass. Following treatment he gradually became morbidly obese and besides subsequent panhypopituitarism he achieved his target height probably due to obesity-induced severe hyperinsulinemia. At the age of 21 Langerhans' cell histiocytosis was diagnosed at the right mandible and was surgically treated. One year later he developed a further painful osteolytic hip lesion and a single zoledronate infusion eliminated all symptoms. We highlight the importance of obtaining a histological diagnosis before initiating treatment, and the distinctive course of the disease in a patient who continued to growth besides GH deficiency.