Multifocal intraparenchymal Langerhans' cell histiocytosis concomitant with an arachnoid cyst in a child: case report and review of the literature.

Langerhans' cell histiocytosis is a disease usually found in children and characterized by idiopathic proliferation of histiocytes in the reticuloendothelial system. Intracranial Langerhans' cell histiocytosis presenting as multifocal intraparenchymal lesions is very rare. In this article, the authors report on a 4-year-old boy diagnosed with multifocal intraparenchymal Langerhans' cell histiocytosis concomitant with an arachnoid cyst. After a series of laboratory examinations, the right frontal mass was surgically excised. Histological examinations confirmed the diagnosis of intracranial Langerhans' cell histiocytosis. The patient's intracranial hypertension symptoms were alleviated, and the remaining foci were treated by Langerhans' cell histiocytosis-directed standard chemotherapy. At the 8-month follow-up visit, no recurrence of the excised lesion was found, and no change in the size of other lesions was seen. Supratentorial intracerebral lesions with mass effect and enhancement have rarely been described; in this report, the histological features of and therapeutic options for such a case are discussed.