Unifocal Langerhans’ cell histiocytois

     Purpose: To report a case of unifocal Langerhans’ cell histiocytosis localized to the superolateral wall of the orbit. A brief review of the main clinicopathologic and CT imaging features is made.

     Methods: Case report. A 4-year-old girl was initially examined with a 4-week history of slowly progressive blepharoptosis and periorbital swelling of the right eye. Results: Computed tomographic scan showed a mass in the right orbit eroding into the right frontal bone; exploratory orbitotomy with biopsy revealed the presence of histiocytic cells with eosinophilic cytoplasm and convoluted nuclei, S100 immuno­reactivity, and tennis-racket-shaped Birbeck granules (electronic microscopy) confir­ming the diagnosis of Langerhans’ cell histiocytosis. Systemic evaluation for other possible tumor localization was negative. The patient was treated with oral prednisone. Four months after initial examination the monostotic Langerhans’ cell histiocytosis had completly resolved.

     Conclusion: Langerhans’ cell histiocytosis is not a well-defined or predictable disease. Instead, it is a spectrum of disorders of unknown etiology that vary widely in presentation and natural history, but have in common the proliferation of histiocytic cells and infiltration of these cells into normal tissues. Lesions may developed in any tissue, but bone, skin and lymph nodes are the most commonly affected. The orbital bones are an occasional site of involvement, most commonly involving the orbital frontal bone. The disease can be unifocal (eosinophilic granuloma), multifocal (Hand-Shuller-Christian disease) or systemic (Letterer-Siwe disease). Unifocal Lan­gerhans’ cell histiocytosis is a rare, benign, proliferative disorder with a median age of diagnosis - 1 to 4 years old. Despite progress in clinical treatment, the etiology and pathogenesis of this disease remain unknown. Treatment may include surgery, corticosteroids or low-dose radiotherapy. There are also some reports of sponta­neous regression.