[A case of pulmonary Langerhans' cell histiocytosis with liver involvement].

We report a case of pulmonary Langerhans' cell histiocytosis with liver involvement in an adult. An asymptomatic 51-year-old man who had, until his referral to our hospital, been a smoker was suspected on examination to have multiple metastases to the lungs and liver. Chest CT showed multiple micronodules, located predominantly in the upper and middle lung fields. Many of these nodules were cavitary. Abdominal US showed multiple, well-defined, round and oval nodules of decreased echogenicity within the liver. Hepatic nodules were enhanced rapidly by contrast-enhanced CT. Comparatively large nodules were demonstrated as well-circumscribed hypoattenuating lesions with ring enhancement. Since further work-up did not demonstrate any evidence of malignancy, open lung biopsy was performed. The results of open lung biopsy were consistent with Langerhans' cell histiocytosis. The infiltrates consisted of variable numbers of Langerhans' cells with folded nuclei and eosinophils. Immunohistochemically, the histiocytes were positive for S-100 protein and CD1a, and negative for CD68. The nodules regressed within 5 months after smoking cessation, and the patient became free of disease 10 months after the initial presentation.