Many patients have a papular rash with brown, red, or crusted areas ranging from the size of a pinhead to a dime. In the scalp, the rash is similar to that of seborrhea. Skin in the inguinal region, genitalia, or around the anus may have open ulcers that do not heal after antibacterial or antifungal therapy. The lesions are usually asymptomatic but may be pruritic. In the mouth, swollen gums or ulcers along the cheeks, roof of the mouth, or tongue may be signs of LCH.
Diagnosis of LCH is usually made by skin biopsy performed for persistent skin lesions.
The relative frequency of bone involvement in adults differs from that in children: mandible (30% vs. 7%) and skull (21% vs. 40%).[1,2,3,4] The frequency in adults of vertebrae (13%), pelvis (13%), extremities (17%), and rib (6%) lesions are similar to those found in children.
Pulmonary LCH in adults is usually single-system disease, but in a minority of patients other organs may be involved, including bone (18%), skin (13%), and diabetes insipidus (5%).
Pulmonary LCH is more prevalent in smokers than in nonsmokers and the male/female ratio may be near unity depending on the incidence of smoking in the population studied.[6,7] Patients with pulmonary LCH usually present with a dry cough, dyspnea, or chest pain, although nearly 20% of adults with lung involvement have no symptoms.[8,9] Chest pain may indicate a spontaneous pneumothorax (10%–20% of adult pulmonary LCH cases). The LCH cells in adult lung lesions were shown to be mature dendritic cells expressing high levels of the accessory molecules CD80 and CD86, unlike LCs found in other lung disorders. In addition, pulmonary LCH in adults appears to be primarily a reactive process, rather than a clonal proliferation as seen in childhood LCH.
The course of pulmonary LCH in adults is variable and unpredictable. Fifty-nine percent of patients do well with either spontaneous remission with cessation of smoking, or with some form of therapy. Adults with pulmonary LCH who have minimal symptoms have a good prognosis, although some have steady deterioration over many years. Age older than 26 years and lower FEV1/FVC ratio and higher RV/TLC ratio are adverse prognostic variables. About 10% to 20% have early severe progression to respiratory failure, severe pulmonary hypertension, and cor pulmonale. Adults who have progression with diffuse bullae formation, multiple pneumothoraces, and fibrosis have a poor prognosis.[13,14] The remainder have a variable course with stable disease in some patients and relapses and progression of respiratory dysfunction in others, some after many years. One study reported that smoking cessation did not increase the longevity of pulmonary LCH patients, apparently because the tempo of disease is so variable. Patients receiving lung transplantation for treatment of pulmonary LCH have a 77% survival rate at 1 year and 54% survival rate at 10 years, with a 20% chance of LCH recurrence.