Eosinophilic granuloma of the orbit: a paradox of aggressive destruction responsive to minimal intervention.

PURPOSE To describe the findings and outcomes in eosinophilic granuloma (unifocal Langerhans cell histiocytosis [LCH]) of the orbit, and to explain the paradox of aggressive bone destruction responsive to minimal intervention. METHODS Retrospective, consecutive, interventional case series of patients treated from 1985 through 2001. Minimum inclusion criteria were demonstration of CD1a positivity or Birbeck granules, treatment by a single surgeon, systemic evaluation by a pediatric oncologist, and follow-up of 12 months. A pathogenetic construct was assembled from general LCH concepts and the specific orbital findings. RESULTS Seven patients met study criteria. All were male, 2 to 16 years of age. All had eyelid or forehead swelling and osteolytic defects, with symptoms of 2 to 6 weeks' duration. All underwent incisional biopsy, with frozen-section examination suggestive of LCH in 6 of 7 cases. The 2 earliest patients received low-dose irradiation after simple biopsy. The 5 most recent patients had subtotal curettage at the time of biopsy; 4 of 5 received simultaneous intralesional corticosteroid injection. In all cases, systemic evaluation showed no other focus of LCH, reossification was timely, and no local recurrence or additional focus was noted in follow-up of 1 to 17 years. CONCLUSIONS Transient immune dysfunction may provoke the cytokine-mediated proliferation of pathologic Langerhans cells within the hematopoietic marrow of the anterolateral frontal bone. These cells cause osteolysis through elaboration of interleukin-1 and prostaglandin E2. Corticosteroids can inhibit the mediators. We recommend incisional biopsy, frozen-section provisional diagnosis, subtotal curettage, intralesional corticosteroid instillation, postoperative systemic evaluation, and long-term follow-up.