CRAN-24. LANGERHANS CELL HISTIOCYTOSIS OF THE ORBIT AND SKULL BASE IN A 2 YEAR OLD: CASE REPORT

Abstract INTRODUCTION Langerhans cell histiocytosis (LCH) results from clonal proliferation of cells which resemble Langerhans cells found normally in skin and lymph nodes. We present an unusual LCH case with significant bony erosion of the lateral orbit and skull base. CASE REPORT A 2 year old girl presented with several weeks of right proptosis. CT and MR imaging showed an enhancing lateral orbital mass eroding the surrounding bony structures and extending into the anterior aspect of the temporal fossa. Surgical approach via orbitozygomatic craniotomy was challenging due to pathologic absence of the zygomatic arch and lateral orbital wall. A near-total resection was achieved based on direct visualization and postoperative MRI. Delayed reconstruction of the lateral orbital wall was planned. Proptosis resolved postoperatively. PET imaging showed residual disease in the middle cranial fossa but no other foci. The patient is currently receiving chemotherapy. DISCUSSION Successful treatment of unifocal LCH usually entails complete surgical excision. Disseminated disease is a poor prognostic factor. Chemotherapy and radiation, including stereotactic radiosurgery, can be employed for residual or nonresectable lesions although long term outcomes are not yet well defined. Delayed reconstruction of bone defects is an option particularly if chemotherapy is anticipated. CONCLUSION LCH of the skull base may radiographically mimic high grade neoplasm, and can be associated with significant bony erosion. Maximal safe resection is an important first step in treatment. Chemotherapy for residual disease and delayed bony reconstruction are important components of comprehensive treatment.