[A case of hypersensitity pneumonitis due to the contamination of a dehumidifier by Thermoactinomyces vulgaris].

A 22-year-old man was admitted to our hospital because of high fever and shortness of breath. A chest CT showed centrilobular nodules and ground-glass attenuation in both lungs. Transbronchial lung biopsy specimens showed alveolitis including the infiltration of mononuclear cells and granulomas. He responded to treatment, but upon returning home the radiological findings and clinical symptoms reappeared. We focused on a dehumidifier because it had been used continuously in his room. Thermoactinomyces vulgaris presented in the air filter of the dehumidifier. The test of precipitation in response to Thermoactinomyces vulgaris was positive. The condition inside the dehumidifier of a high temperature and high humidity were suitable for the proliferation of Thermoactinomyces vulgaris. We diagnosed hypersensitity pneumonitis due to a dehumidifier contaminated by Thermoactinomyces vulgaris.

Pulmonary lymphangioleiomyomatosis; unusual radiological manifestation of multiple large nodules.

A 44-year-old woman was admitted to our hospital in August 1999 for multiple large nodules detected on chest roentgenogram in an annual health check. Chest CT scans showed bilateral large nodules (>10 mm in diameter) with irregular margins and multiple thin walled cystic lesions. From these radiologic examinations, we suspected pulmonary Langerhans cell histiocytosis. Histological examination of the biopsy specimen by video-assisted thoracoscopy revealed a marked proliferation of the spindle cells, which were immunologically positive for alpha-smooth muscle actin and HMB-45, in the cyst walls and lung parenchyma. The large nodules consisted of proliferation of the smooth muscle cells surrounded by a dense layer of hemosiderinladen macrophages. During the two years subsequent to these 1999 examinations, the opacities have gradually diminished and the patient was found to have pulmonary lymphangioleiomyomatosis. This case exhibited rare radiologic manifestations of multiple large nodules mimicking Langerhans cell histiocytosis.