Endobronchial ultrasound-guided cautery-assisted transbronchial mediastinal cryobiopsy in the diagnosis of fibrosing mediastinitis secondary to atypical sarcoidosis: a case report.

BACKGROUND: Fibrosing mediastinitis (FM) secondary to atypical sarcoidosis (atypical presentation of sarcoidosis) is rarely reported at home and abroad. Its clinical manifestations represent a lack of specificity, and the initial diagnosis is frequently difficult. In particular, this case has multiple pulmonary nodules with mediastinal lymph node enlargement and bilateral pleural effusion, and pulmonary fibrosis still exists after treatment, which is inconsistent with any clinical stage of pulmonary sarcoidosis, further increasing the diagnostic difficulty. We retrospectively analyzed the clinical data of a case of FM secondary to atypical sarcoidosis diagnosed by endobronchial ultrasound-guided cautery-assisted transbronchial mediastinal cryobiopsy (EBUS-CA-TBMCB) in Chongqing University Fuling Hospital, to improve clinicians' attention to FM and understand that EBUS-CA-TBMCB remains an effective way of etiological diagnosis.

CASE DESCRIPTION: A 70-year-old man was hospitalized with cough and dyspnea for two months. After admission, through chest computed tomography (CT), ultrasound guided bilateral lung biopsy, left parietal pleural biopsy, and EBUS-CA-TBMCB, the final diagnosis was atypical sarcoidosis secondary FM. After taking glucocorticoid orally, the patient's condition improved significantly, and was discharged from the hospital. We continued following up outside the hospital, and the patient's condition was further improved.

CONCLUSIONS: The diagnosis of FM is mainly based on typical imaging manifestations. When the contrast-enhanced chest CT finds localized or diffuse soft tissue density shadows around the mediastinum and pulmonary hilum with an irregular shape, with or without calcification, particular attention should be paid to exclude FM. EBUS-CA-TBMCB, as an improved minimally invasive method, can obtain enough tissue samples for pathological diagnosis, which may be the effective biopsy method for the etiology of FM to avoid missed diagnosis and misdiagnosis in the future.