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Localized pulmonary AL amyloidoma mimicking malignancy: bilateral spiculated nodules with misleading bone marrow FDG uptake

Year: 2026

Type: article

Abstract: Localized pulmonary AL (lambda) amyloidoma is a rare entity that may closely mimic lung malignancy on cross-sectional and metabolic imaging. This combination of bilateral spiculated nodule morphology and misleading bone marrow fluorodeoxyglucose (FDG) uptake has been rarely reported and represents a diagnostically challenging presentation of this condition. A 44-year-old woman presented with a four-month history of exertional dyspnea, dry cough, and back pain. Chest computed tomography (CT) revealed multiple bilateral pulmonary nodules, including a dominant irregular spiculated lesion. FDG positron emission tomography/computed tomography (PET-CT) demonstrated low-level uptake in the pulmonary nodules together with diffuse low-grade axial bone marrow FDG uptake, raising concern for metastatic disease or plasma cell dyscrasia. Bronchoscopy was non-diagnostic. Robotic-assisted thoracic surgery (RATS) established the diagnosis of localized pulmonary AL amyloidoma, supported by Congo red positivity, apple-green birefringence under polarized light, and lambda light-chain immunohistochemical positivity, with negative staining for alternative amyloid subtypes. Subsequent evaluation, including repeated serum and urine immunofixation, serum free light chain assessment, bone marrow biopsy, echocardiography, and renal evaluation showed no evidence of systemic amyloidosis or a clonal plasma cell disorder. Residual contralateral nodules remained stable on follow-up imaging. Localized pulmonary amyloidoma may present with bilateral spiculated nodules and misleading bone marrow FDG uptake, closely simulating both pulmonary malignancy and plasma cell dyscrasia. Surgical biopsy, accurate amyloid subtyping, and multidisciplinary systemic assessment should be considered essential components of the diagnostic approach to avoid unnecessary oncologic or hematologic treatment. Not applicable.

Source: BMC Pulmonary Medicine

DOI: 10.1186/s12890-026-04820-z