A 52-year-old patient visited our hospital with dyspnea on exertion which had started three years previously and worsened over the previous three weeks. Three years ago when the symptom started, he had visited a local clinic and underwent bronchoscopy which showed bronchial narrowing. At that time, he received no treatment.
He had type 2 diabetes mellitus and took oral hyperglycemic agents (metformin 1000mg, glimepiride 4mg, and acarbose 100mg twice daily). His hemoglobin A1c level was 7.1%. He was a 17.5-pack-year current smoker. He had undergone a cranial operation due to trauma. His father had a history of tuberculosis, and his mother had diabetes mellitus.
A chest radiograph and a chest computed tomography (CT) scan revealed neither focal haziness in the lungs nor obstruction of the airways (Fig. 1A-B). A pulmonary function test showed a moderate obstructive pattern. The CT scan showed tracheobronchial wall calcification from the trachea to the main bronchi and segmental bronchi (Fig. 1C-D). In the trachea, the nodules were prominent in the cartilaginous portion, while in the right and left main bronchi, luminal narrowing with calcification and mucus plugging were found.
Under bronchoscopy, the whole trachea, the right middle and lower, and the left main and lingular bronchi were covered by submucosal whitish nodules with capillary dilatation (Fig. 2). Some bronchi were nearly obstructed by the nodules. The tissues were resected for pathology, and a biopsy sample was obtained from the right main bronchus.
The pathology showed pinkish amorphous deposition in the bronchial wall with multifocal osteochondroid metaplasia (Fig. 3A). Using Congo-red staining, apple-green birefringence was observed under the polarized microscope (Fig. 3B). Amyloid typing was not done.
The patient underwent abdomen skin biopsy and it showed no amyloid deposition. He had no albuminuria on dipstick test and had normal serum albumin-to-globulin ratio, which suggests that it is not likely for him to have systemic protein-producing disease or diabetes mellitus with complication.
He was diagnosed with TPO associated with TBA and started taking methotrexate once weekly. His lung function improved: forced expiratory volume in 1 second (FEV1) increased from 2.03 L to 2.24 L after rigid bronchoscopy laser resection. After following up for 3 years with methotrexate maintenance, his symptoms and pulmonary function were stable and the patient was referred back to the local clinic.