A 60-year-old man with history of left nephrectomy for clear cell renal cancer (stage I) and resected colorectal adenocarcinoma (stage II) presented with a pulmonary mass lesion in the left upper lobe on surveillance imaging. Transaxial CT (B) revealed a 2.9 cm slightly lobulated lesion in the inferior lingular segment of the left upper lobe overlying the left oblique fissure. 18-F FDG PET/CT images (A, C, D) demonstrated moderate to marked FDG avidity (SUVmax 6.4) in this lesion.\nHistopathology of CT-guided core needle biopsy showed tumour cells with relatively uniform nuclear and clear cell cytoplasm with positive staining for PAX8 and renal cell antigen, consistent with metastatic renal cell carcinoma. The patient underwent wedge resection of the left upper lobe metastasis with clear excisional margins.\n6 months later, follow-up imaging with 18-F FDG PET/CT and diagnostic CT was performed. Transaxial CT (B) demonstrated a slowly enlarging subcentimeter 9mm pulmonary nodule in the right upper lobe. Maximum intensity projection, transaxial fused PET/CT and transaxial PET (A, C, D) images demonstrated moderate FDG avidity (SUVmax 4.6 on current PET, SUVmax 2.4 on previous PET (not shown)) in this lesion. No other suspicious FDG avid focus was detected. Given the proven pulmonary metastatic disease from renal cell cancer, further small volume oligometastatic disease was suspected. Reliable needle biopsy of the lesion was considered difficult due its small size and deep location. The patient subsequently underwent segmental resection of this sub centimeter pulmonary nodule.\nHistopathology of the second pulmonary nodule demonstrated no evidence of malignancy. Instead, there was amorphous hyaline acellular amyloid-like material associated with a rim of multinucleated inflammatory cells (). The chronic inflammatory cells comprised mainly of mature plasma cells with smaller numbers of lymphocytes. Crystal violet stain was positive, and the Congo red stain demonstrated focal birefringence, confirming nodular pulmonary amyloidosis. The patient continues to be under observation for further tumour recurrence.
A 64-year-old man presented with an incidental right lung mass on chest X-ray. Mediastinoscopy and lymph node biopsy confirmed amyloid, remaining asymptomatic until four years later, developing exertional dyspnoea matched by significant increase of the mass by chest radiography. Basic laboratory evaluation and immunohistochemistry was unremarkable. Immunoelectrophoresis revealed a faint immunoglobulin G (IgG) kappa band. No mass spectrometry was performed. Colonic biopsy, bone marrow aspirate, immunophenotyping and trephine were normal. 123I Serum amyloid P-component (SAP) scintigraphy showed abnormal uptake within the mass only. Computerised tomography (CT) revealed mediastinal and hilar lymphadenopathy, with a 9.5 × 6.5 × 10 cm right mediastinal mass containing fat and calcification with a radiological differential diagnosis of a teratoma. F-18 fluorodeoxyglucose (FDG)-Positron Emission Tomography (PET)/CT demonstrated intermediate to high-grade uptake within the soft tissue and low-grade uptake in the fatty component (). Cardiac magnetic resonance imaging excluded cardiac involvement. Repeat core biopsy demonstrated fibrovascular tissue with focal amyloid deposition. The patient proceeded to surgical mass de-bulking for diagnosis and symptom relief and histology confirmed evidence of amyloid. The patient’s postoperative course was uneventful; no evidence of recurrence three months following surgery and marked symptomic improvement, with disappearance of the IGgk paraprotein following resection, currently planned for local consolidation radiotherapy.