Concomitant diagnosis of hypersensitivity pneumonitis and localized epithelioid mesothelioma: a rare case report.

Hypersensitivity pneumonitis is an inflammatory lung disease caused by antigen inhalation after sensitization. Here, we report a rare case of the simultaneous diagnosis of hypersensitivity pneumonitis and epithelioid mesothelioma, a subtype of malignant mesothelioma. A 71-year-old man presented with an occasional dry cough and exertional dyspnea that had persisted for about 1 year. He reported walking daily in a park with a considerable number of birds during same period. Functional evaluation revealed a mild restrictive ventilatory disorder. High-resolution computed tomography showed nonspecific peripheral interstitial lung involvement along with signs of bronchopathy and diffuse bronchiolopath without honeycombing or bronchiectasis. Owing to the patient's clinical history and the presence of a restrictive ventilatory disorder, a biopsy was performed for diagnostic clarification. Pathological examination revealed hypersensitive pneumonitis associated with epithelioid mesothelioma. Surgical resection of the mesothelioma and avoidance of occupational exposure resulted in complete regression of symptoms and improvement in radiological findings. A report on this rare concomitant diagnosis of the hypersensitivity pneumonitis and epithelioid mesothelioma is essential for advancements in medicine.