Transbronchial cryobiopsy for diagnosing pulmonary hyalinizing granuloma: a case report

Pulmonary hyalinizing granuloma (PHG) is a rare, benign pulmonary disease characterized by dense hyalinized collagen deposition. Diagnosis is often challenging because conventional transbronchial forceps biopsy frequently fails to obtain adequate tissue samples, necessitating surgical lung biopsy. While transbronchial cryobiopsy has been successfully employed in similar sclerotic diseases, its use in PHG has not been reported to date. Herein, we present a case of PHG diagnosed using transbronchial cryobiopsy.

A 61-year-old man was evaluated due to a 5-mm nodular lesion in the right lower pulmonary lobe incidentally detected on chest computed tomography performed as part of a routine health check-up. He was asymptomatic, and physical examination revealed no remarkable clinical findings. Over a 2-year follow-up, the lesion enlarged slightly to 6 mm. Bronchoscopy revealed a firm, whitish endobronchial tumor in the right B10 bronchus. Forceps biopsy was unsuccessful due to the lesion's hardness. Transbronchial cryobiopsy using a 1.7-mm cryoprobe successfully obtained a sufficient tissue sample. Histopathological examination showed dense hyalinized collagen bundles with lymphoplasmacytic infiltration, consistent with PHG. No immediate complications occurred. The lesion remained stable during 18 months of follow-up without intervention.

This case suggests that transbronchial cryobiopsy may be a useful, less-invasive option for diagnosing firm, fibrotic pulmonary lesions, including PHG, and may help reduce the need for surgical procedures in selected patients.