Calvarial Langerhans cell histiocytosis in an adult presenting rapid growth.

Background:Langerhans cell histiocytosis (LCH) arising in the skull is rare in adulthood. Case Description:A 58-year-old woman experienced a durable headache. Cerebral magnetic resonance imaging (MRI) at presentation showed no abnormalities; however, MRI and computed tomography (CT) performed 6 weeks later revealed the emergence of a well-demarcated, heterogeneously enhancing calvarial tumor accompanied by irregular-shaped bone erosion. On MRI, the temporalis muscle and subcutaneous tissue adjacent to the tumor were extensively swollen and enhanced. The patient underwent en bloc resection. The microscopic appearance of the tumor was consistent with that of LCH. Postoperative systemic 18F-fluorodeoxyglucose positron emission tomography/CT did not detect any abnormal accumulation. Conclusion:LCH may develop within a short period. It should be considered as a differential diagnosis when a rapidly growing calvarial tumor is encountered, even when the patient is an adult. Prompt histological verification is recommended in such cases.