Complete resolution of non-tuberculous mycobacterial pulmonary nodule following cryobiopsy: The first case report

Non-tuberculous mycobacterial (NTM) lung disease presents diagnostic and therapeutic challenges, often mimicking lung cancer, tuberculosis, and other bronchopulmonary disorders. Management typically involves prolonged antibiotic treatment, but alternative therapeutic approaches for localized disease remain underexplored. Cryobiopsy has emerged as an advanced bronchoscopic diagnostic technique, providing larger, higher-quality lung tissue samples compared to traditional forceps biopsy. However, its potential therapeutic effects, particularly its unintended cryoablation effect, remain an area of active investigation.

A 46-year-old healthy woman was incidentally found to have a 1.3-cm pulmonary nodule in the left anterior basal segment during a routine health examination, with no symptoms or significant medical history. Initial CT imaging raised suspicions of T1a lung cancer. Subsequent endobronchial ultrasound transbronchial lung biopsy and transbronchial lung cryobiopsy revealed granulomatous inflammation. Tests for tuberculosis and NTM, including acid-fast bacilli (AFB) smear, mycobacterial culture, and PCR for Mycobacterium tuberculosis and NTM, were negative. Following the biopsies, chest X-rays showed an enlarged shadow at the lesion, suggesting necrosis after cryobiopsy. The patient was treated with moxifloxacin, leading to symptom improvement. A final diagnosis of NTM infection, specifically Mycobacterium avium, was confirmed from bronchoalveolar lavage fluid obtained three weeks after the tissue biopsy. Remarkably, at four months post-biopsy, a chest CT scan showed complete resolution of the nodule without additional antimicrobial therapy, suggesting a potential therapeutic effect of cryobiopsy-induced cryoablation.

NTM nodules may undergo necrosis and resolve due to the ablation effect of cryobiopsy, suggesting cryoablation as a potential option for inoperable localized NTM disease.