Pulmonary Amyloidosis Diagnosed by Transbronchial Lung Biopsy: A Three-Case Series With Diverse Radiological Manifestations.

Pulmonary amyloidosis is a rare disease with diverse radiological manifestations that may mimic malignancy or diffuse interstitial lung disease. Although conventional forceps transbronchial lung biopsy (TBLB) is an established less invasive diagnostic method, its clinical role may differ according to disease presentation. We report three patients with pulmonary amyloidosis diagnosed by conventional forceps TBLB. Two presented with nodular lesions mimicking malignancy; TBLB established the diagnosis, and systemic evaluation showed no extrapulmonary involvement, supporting localized pulmonary amyloidosis. The third presented with progressive weight loss and diffuse interlobular septal thickening. TBLB unexpectedly demonstrated pulmonary amyloid deposition, prompting systemic and haematological evaluation that revealed systemic AL amyloidosis associated with multiple myeloma. These cases illustrate distinct roles of conventional forceps TBLB: distinguishing localized nodular amyloidosis from malignancy and, in diffuse alveolar-septal disease, providing an initial clue prompting evaluation for systemic amyloidosis.