Histiocytosis X

Histiocytosis X is a group of disorders (Letterer-Siwe disease, Hand-Schüller-Christian disease, eosinophilic granuloma) in which abnormal scavenger cells called histiocytes and another immune system cell type called eosinophils proliferate, especially in the bone and lung, often causing scars to form.

Letterer-Siwe disease starts before age 3 and is usually fatal without treatment.  The histiocytes damage not only the lungs but also the skin, lymph glands, bone, liver, and spleen.  Collapse of a lung (pneumothorax) may occur.

Hand-Schüller-Christian disease usually begins in early childhood but can start in late middle age.  The lungs and bones are most frequently affected.  Rarely, damage to the pituitary gland causes bulging eyes (exophthalmos) and diabetes insipidus, a condition in which large quantities of urine are produced, leading to dehydration.

Eosinophilic granuloma tends to start between ages 20 and 40.  It usually affects the bones but also affects the lungs in 20% of people; sometimes only the lungs are involved.  When the lungs are affected, the symptoms can include coughing, shortness of breath, fever, and weight loss, but some people have no symptoms.  Collapse of a lung (pneumothorax) is a common complication.

Treatment and Prevention

All three disorders may be treated with corticosteroids and cytotoxic drugs such as cyclophosphamide, although no therapy is clearly beneficial.  The therapy for bone involvement is similar to that for bone tumors.

Prognosis; Complications

People with Hand-Schüller-Christian disease or eosinophilic granuloma may recover spontaneously.

Death usually results from respiratory failure or heart failure.