Abstract Introduction The differential diagnosis for a solitary pulmonary nodule (SPN) is broad and ranges from benign conditions to infectious to malignant. One of the rarest etiologies is nodular pulmonary amyloidosis (NPA) which can present as an SPN in the form of an amyloidoma, often found incidentally on chest imaging (1). We present a woman with a history of tobacco use and suspicious appearing SPN requiring biopsy. Case Description An 80-year-old woman with a 53-pack year history presented to her PCP office with chief complaint of prolonged post-infectious cough after a bout of pneumonia 4 months prior. Computed tomography (CT) scan of the chest was ordered which revealed a spiculated 16 mm SPN in the superior segment of the right lower lobe concerning for malignancy. She was referred to pulmonology for further evaluation and biopsy. Positron emission tomography (PET) CT was completed and showed mild metabolic activity of the SPN but no other suspicious lesions. Bronchoscopy with biopsy was performed and final pathology showed amyloid deposition consistent with amyloidoma. Further laboratory work up including serum protein electrophoresis (SPEP) and serum light chains were normal. Bone marrow biopsy was completed and showed no evidence of systemic amyloidosis. Discussion Amyloidosis in the lung can present in 3 variations: NPA, diffuse alveolar-septal amyloidosis, and tracheobronchial amyloidosis (2). The latter two generally are associated with systemic amyloidosis and almost always require treatment, whereas NPA generally does not. Interestingly, there are studies that have shown many cases of NPA are associated with underlying marginal zone lymphoma of mucosa-associated lymphoid tissue, or MALT lymphoma (1-5). Diagnosis of NPA requires work-up for systemic amyloidosis (1). If found, systemic amyloidosis treatment is based on a number of factors including location of disease and staging, amongst other factors (6). Isolated NPA in the absence of significant symptoms generally does not require treatment but should have ongoing surveillance for growth of amyloidoma or the development of systemic amyloidosis or underlying lymphoproliferative disorder (5). Fortunately for our patient her SPEP and serum light chain studies were negative, as was her bone marrow biopsy, making this an isolated case of NPA. While generally considered a “benign” cause of SPN, case reports have shown that amyloidomas can grow to be quite large and even destructive (7). Clinic suspicion must remain high in the diagnosis of this rare disease and care must be taken on the part of the clinician to ensure appropriate follow-up. This abstract is funded by: None
Ostertag et al. (Fri,) studied this question.