An unusual case of nodular pulmonary amyloidosis
Nodular pulmonary amyloidosis is a rare and localized manifestation of amyloid deposition in the lungs. This rare entity, though asymptomatic, is often misdiagnosed on imaging alone, due to its resemblance to metastatic pulmonary nodules. This report highlights the significance of histologic confirmation before treatment, as a preventive measure against overtreatment.

A 71-year-old Caucasian gentleman was referred to the General Thoracic Surgery Clinic due to a left upper lobe nodule. This patient is a heavy smoker and was known for a history of interstitial lung disease (ILD), which had been followed by routine CT chest for several years. There was no history or suspicion of amyloidosis in this patient. The most up-to-date CT scan showed slight enlargement of an irregular solid left upper lobe nodule, measuring 1.2 × 1.0 cm in size. His scan also showed peripheral reticulation in a pattern consistent with a usual interstitial pneumonia (UIP), most likely related to an idiopathic pulmonary fibrosis but overall stable from previous screening.

At the time, the patient was asymptomatic and appeared to be otherwise reasonably healthy based on physical and laboratory assessments. A subsequent PET CT scan 1 month later confirmed the presence of the nodule of concern with indeterminate FDG uptake and other features consistent with active fibrosis.

Given the patient's age and history of ILD, he was at risk for pulmonary malignancy and a higher risk for complications from either minimally invasive resection or even stereotactic body radiation therapy (SBRT).

The pathology result was consistent with amyloidoma, a relatively rare manifestation within the lungs. Although there was limited lymphoid infiltrate, no definitive diagnostic evidence of lymphoma or plasma cell neoplasm was identified in the examined material of this biopsy. Since the nodule was not symptomatic, there was no need for intervention at that time and a CT-scan follow-up was ordered to monitor nodule size.