Langerhans' Cell Granulomatosis
Langerhans' cell granulomatosis (histiocytosis X) is a group of disorders (Letterer-Siwe disease, Hand-Schüller-Christian disease, pulmonary histiocytosis X) in which cells called histiocytes and eosinophils proliferate, especially in the bone and lung, often causing scarring.
The cause of these disorders is not known. They all start with infiltration of the lung (and other tissues) by histiocytes, which are cells that scavenge for foreign materials, and to a lesser extent by eosinophils, which are cells that are normally involved in allergic reactions.
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, bones, liver, and spleen. A small portion of the lung may rupture into the pleural space (a condition called pneumothorax (see Section 4, Chapter 52)).
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 diabetes insipidus (see Section 13, Chapter 162), a condition in which large quantities of urine are produced, leading to dehydration. Some people develop bulging eyes (exophthalmos) because the bones of the eye sockets are affected.
Pulmonary histiocytosis X (eosinophilic granuloma) is a rare, smoking-related lung disease. The disease occurs more often in men than in women. Symptoms usually start between the ages of 20 and 40. About 16% of people have no symptoms, but the rest develop coughing, shortness of breath, fever, chest pain, and weight loss. Pneumothorax is a common complication due to rupture of a lung cyst. Scarring makes the lungs stiff and impairs their ability to transfer oxygen into and out of the blood.
Diagnosis
Chest x-rays show nodules, small lung cysts (honeycombing), and other changes that are typical of these diseases. X-rays may also show that the bones are affected. Pulmonary function tests show reduced function. Coughing up of blood (hemoptysis) and diabetes insipidus are rare complications.
Prognosis and Treatment
People with Hand-Schüller-Christian disease may recover spontaneously. Most people with pulmonary histiocytosis X have persistent or progressive disease. Death usually results from respiratory failure or cor pulmonale (see Section 4, Chapter 54), although when people with pulmonary histiocytosis X stop smoking, improvement occurs in about one third of cases.
All three disorders may be treated with corticosteroids and immunosuppressant drugs such as cyclophosphamide, although no therapy is clearly beneficial. The treatment for affected bones is similar to that for bone tumors (see Section 5, Chapter 63).
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