Pulmonary Langerhans' cell granulomatosis (histiocytosis or eosinophilic granuloma) is a disorder in which cells called histiocytes and eosinophils proliferate in the lung, often causing scarring.
Pulmonary Langerhans' cell granulomatosis (histiocytosis) is one form of Langerhans' cell granulomatosis, which can affect other organs (such as the pituitary gland and the white blood cells) as well as the lungs. The cause is unknown, and the disorder is rare. It occurs almost exclusively in whites aged 20 to 40 who smoke cigarettes. It starts with infiltration of the lung 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.
About 15% of people have no symptoms and the disorder is first recognized when an imaging study of the chest is done for another reason. The remainder develop coughing, shortness of breath, fever, chest pain, fatigue, and weight loss. Pneumothorax is a common complication due to rupture of a lung cyst. It occurs in 15 to 25% of people with the disorder and may be the cause of the first symptoms that develop. Scarring makes the lungs stiff and impairs their ability to transfer oxygen into and out of the blood. A few people cough up blood (hemoptysis).
Some people have localized bone pain or a pathologic bone fracture (a fracture that occurs with only a minor injury because the bone has been thinned by a disorder). Diabetes insipidus occurs in about 15% of people. This condition results when histiocytes also affect the hypothalamus in the brain. The person makes excessive amounts of urine that is dilute. People with diabetes insipidus probably have a worse prognosis than those who do not.
Chest x-rays show nodules, small lung cysts (honeycombing), and other changes that are typical of this disorder. Computed tomography (CT) may show these changes in enough detail to establish the diagnosis. X-rays may also show that the bones are affected. Pulmonary function tests show that the amount of air the lungs can hold is below normal. If CT is not diagnostic, biopsy is required. Biopsy can usually be done during bronchoscopy (see see Bronchoscopy).
Prognosis and Treatment
Half of people are alive more than 12 years after diagnosis. Death usually results from respiratory failure or cor pulmonale (see see Sidebar 1: Cor Pulmonale: A Disorder Stemming From Pulmonary Hypertension). When people stop smoking, improvement occurs in about one third of cases.
The disorder may be treated with corticosteroids and immunosuppressants such as cyclophosphamide, although no therapy is clearly beneficial.
Last full review/revision March 2008 by Talmadge E. King, Jr., MD