Adult Langerhans Cell Histiocytosis Diagnosed by Biopsy of the Skull Tumor Generated after Craniotomy

Langerhans cell histiocytosis (LCH) is a disease characterized by the proliferation of Langerhans cells. Most cases of LCH occur in children, although it can be seen in adults as well. We encountered an adult case of LCH. A 44-year-old woman who was diagnosed as diabetes insipidus underwent a magnetic resonance imaging (MRI) of the head which revealed sellar and suprasellar gadolinium-enhanced mass. Prolactin level was high and cabergoline was prescribed. The size of this mass had reduced, so we supposed the tumor was prolactinoma. However, after 4 years of observation, it had increased once again. The biopsy of pituitary stalk lesion was performed via transcranial approach. The histological diagnosis was initially gangliocytoma. The patient complained of back pain after surgery. Three months after the biopsy, a computed tomography (CT) scan revealed multiple osteolytic lesions throughout the entire body. One of the osteolytic lesions of the skull was removed to determine the diagnosis. The pathological examination of the skull led to a diagnosis of LCH. We concluded retrospectively that the lesion of the pituitary stalk was LCH mimicking gangliocytoma though classical pathological findings were not obtained. In conclusion, LCH should be considered as a differential diagnosis in adult cases of diabetes insipidus with hypothalamic–pituitary lesion.