Langerhans'Cell Histiocytosis of the Orbit

ABSTRACT

Langerhans'cell histiocytosis[LCH], or histiocytosis X, is an uncommon multisystemic disorder of unknown etiology, which is characterized by accumulation of histiocytes in various tissues including orbit. We have recently experienced 4 cases of orbital LCH presenting with exophthalmos. Four patients[3 children and 1 adult]presented with exophthalmos that progressed over 2 to 3 weeks and were found to have orbital mass on ocular examination and orbital CT scan. Two children had concomitant hepatomegaly. Orbital CT scan showed a soft tissue mass with destruction of adjacent bones. Microscopic examination of the orbital mass showed a collection of Langerhans 'cells intermixed with eosinophils and other inflammatory cells. In two cases, immunohistochemistry revealed positive staining for S-100 protein. In three cases, a definite diagnosis was made by detection of Birbeck's granules by electron microscopy. Three children received chemotherapy and one adult had mass excision. The mass markedly decreased in size or nearly disappeared in all patients, and no recurrence has been noted for more than 9 months of follow-up.