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 59-year-old Chinese female was referred to the chest clinic of the First Affiliated Hospital, College of Medicine, Zhejiang University (Hangzhou, China) in April 2011 due to a two-month history of cough, hemoptysis and general fatigue. A CT scan of the chest revealed a nodule in the left lower lung with mild enhancement in the lesion. The nodule progressed during the two-month follow-up period under treatment with anti-infection drugs. No other significant history was noted. The patient’s physical examination was unremarkable, and hematological and biochemical parameters were within normal limits.\nA dual phase FDG PET/CT scan was performed following six hours of fasting. FDG (5.5 MBq/kg) was injected intravenously through an antecubital vein while the patient remained at rest. Image acquisition was subsequently conducted using a Siemens Biograph 16 PET-CT scanner (Siemens Medical Solutions USA, Inc., Malvern, PA, USA). The PET/CT images revealed a 1.83×1.40 cm slightly lobulated nodule, with burr-like margins in the left lower lung, exhibiting moderately increased F-18 FDG uptake (maximum SUV of 2.6) in the initial images (1 h following the FDG injection), and more intense FDG uptake with an SUV of 3.5 (26.9% increase) in the delayed images (2 h following the injection) (). Based on the dual phase FDG PET/CT imaging findings, morphological features, contrast-enhanced chest CT imaging and medical history (progression of the nodule during the two-month follow-up period), lung malignancy was highly suspected. A percutaneous CT-guided thoracoscopic biopsy was subsequently performed. Histological examination revealed that the specimens contained amorphous, homogeneous material with a number of polyclonal plasma cells, lymphocytes and giant cells. Eosinophilic material exhibited apple-green birefringence under polarizing microscopy. Immunohistochemically, congo red staining was positive, and trichrome staining was negative, confirming the deposition of amyloid within the specimen (). Therefore, a diagnosis of primary nodular parenchymal pulmonary amyloidosis was determined, and the patient was discharged without chemotherapy and other treatment. After May 2011, the patient was followed up every 3 months and was in good clinical condition at the time of writing.