Isi Esquenazi; Kimberly G. Yen, MD; Douglas P. Marx, MD

Disclosures

February 28, 2013

Discussion

LCH is an uncommon disorder characterized by the clonal proliferation of Langerhans cells, a type of histiocyte such as the macrophage and dendritic cell. It has a greater propensity to affect males and children between 2 and 4 years of age.[1] LCH is found in 3 recognized forms: Letterer-Siwe disease, Hand-Schuller-Christian disease, and eosinophilic granuloma. Letterer-Siwe disease has widespread soft tissue and visceral involvement and can be fatal. Hand-Schuller-Christian disease is the intermediate form of histiocytosis, characterized by the triad of exophthalmos, bony defects of the skull, and diabetes insipidus. Finally, eosinophilic granuloma is the most common and indolent form, characterized by chronic bone lesions with focal proliferation and infiltration of histiocytes, which have a bean-shaped nucleus on biopsy.[1,2] Extraskeletal manifestations may also be seen, most commonly on the skin, lymph nodes, lungs, liver, and bone marrow.[1]

LCH is rarely encountered in ophthalmic practice. In LCH, the orbit is the most commonly involved site encountered by ophthalmologists.[3] The incidence of orbital involvement in LCH has been reported to be 1%-20%.[2] It usually presents with acute or chronic orbital swelling as well as proptosis, which was seen in our patient. Immunohistochemical analysis of cellular proteins like S100, langerin, and CD1a can aid in the diagnosis of LCH. According to the Histiocyte Society, the diagnostic criteria for LCH include CD1a, S100, and langerin positivity or the presence of Birbeck granules on electron microscopy in the appropriate clinical setting.[1] However, in cases of orbital LCH with multisystem disease like our patient's, a biopsy of the orbital mass is the most practical and definitive way of making a diagnosis.

Intraocular involvement with LCH is rare. It is usually seen in the disseminated form of the disease (ie, Letterer-Siwe disease), consisting of infiltration of the intraocular structures, especially the uveal tract. Cases have been reported, however, of infiltration of the choroid, retina, iris, and vitreous. Patients with intraocular LCH can also develop uveitis and hyphema. The prognosis of intraocular LCH is less favorable than that of orbital LCH.[4]

Various treatment options are available for LCH, including but not limited to surgical curettage, local corticosteroid injections, low-dose radiotherapy, high-dose systemic corticosteroids, and chemotherapy. The choice of regimen is based upon the number of organ systems involved and the severity of disease. Continuation therapy is recommended to all patients regardless of whether or not there is evidence of disease after the initiation phase.[5]

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