Langerhans cell histiocytosis in the elderly: a report of three cases.

Langerhans cell histiocytosis is most common in children and is unusual in the elderly. We describe 3 cases of langerhans cell histiocytosis limited to the skin in elderly patients. Biopsy specimens showed a dermal infiltrate abutting the epidermis composed of atypical langerhans cells with abundant eosinophilic cytoplasm and a "kidney-shaped" nucleus. Immunoperoxidase stain CD1a was positive in all 3 cases and S-100 stain was positive in 2. Electron microscopy revealed Birbeck granules in the cytoplasm of the atypical langerhans cells in 2 cases. Langerhans cell histiocytosis with skin involvement has a chronic course with an overall good prognosis. However, cutaneous manifestations may precede systemic involvement by many years.