Histiocytoses – X Type Overview

X Type Histiocytosis is a very rare disease that I only seldom encounter in both my The Woodlands dermatology and Conroe dermatology offices.  X Type Histiocytosis is a disease of Langerhans cell proliferation that involves not only the skin but multiple organ systems such as the bones, spleen, liver, lymph nodes, endocrine glands, central nervous system and lungs.  In the past, X Type Histiocytosis was classified as either Letterer-Siwe disease or Hand-Christian-Schuller disease.  Currently, the classification is based on whether it is single organ involvement or multisystem disease.  X Type Histiocytosis can occur at any age from birth to adulthood but is most often seen in early childhood.  The cause of X Type Histiocytosis is unknown.  The skin is the most common organ affected in children with this disease, whereas in adults the bones and lungs are the most common organs involved.  The typical skin lesions are red/brown/yellow papules that are most commonly found in the groin, axilla, behind the ears, and scalp.  Clinically, the skin lesions may resemble seborrhea but with a more papular appearance.  The nails are occasionally involved and can become dystrophic.  The most common internal organ involved is the bones with the skull being the affected most often.  Endocrine disorders usually are related to diabetes insipidus.  Prognosis is related to the extent of the disease and the age of presentation.  Treatment typically involves chemotherapy and/or radiation.