Stereotactic Radiosurgery for Localized Cranial Langerhans Cell Histiocytosis: A Single Institution Experience and Review of Literature.

BACKGROUND: Langerhans cell histiocytosis (LCH) is a rare idiopathic disease characterized by the clonal proliferation of Langerhans histiocytes in various parts of the body and capable of leading to organ damage and tumor formation. Reports of cranial LCH in the adult population are extremely rare. Although surgery remains the preferred option for localized LCH lesions, the role of stereotactic radiosurgery (SRS) is emerging. OBJECTIVE: To retrospectively review a rare case series to determine the safety and effectiveness of SRS for patients with localized cranial LCH. METHODS: We retrospectively reviewed histopathologically confirmed cases of localized cranial LCH treated with SRS at our institute in the adult population between January 2005 and September 2022. Five patients were identified with a median age of 34 years (19-54 years). The tumor location was in the pituitary stalk in 3 patients, the orbit in one patient, and the parietal skull in one patient. The median target volume was 2.8 cc (range: 0.37-6.11). Treatment was delivered in a single fraction in 4 patients (median margin dose of 8 Gy, range: 7-10 Gy) and in 3 fractions (22.5 Gy) in 1 patient. The median follow-up was 12 years (range: 4-17). None of the patients required craniotomy for tumor debulking before or after SRS. RESULTS: The local tumor control rate for the lesions was 100%. All 3 patients with LCH in the pituitary stalk had diabetes insipidus at the initial presentation and developed panhypopituitarism after SRS. Diabetes insipidus was not improved after SRS. The other 2 patients presented no adverse radiation effects. Based on the literature review, our case series was the largest retrospective series on SRS for localized cranial LCH, with the longest median follow-up. CONCLUSIONS: SRS for patients with localized cranial LCH was a safe and effective treatment modality in this case series. Larger studies are encouraged to validate the role of SRS in the treatment of localized cranial LCH.