A Unique Case of Pulmonary Hyalinizing Granuloma Associated With FDG-avid PET Scan and Deep Venous Thrombosis

Abstract

An 83-year-old obese woman with a 60-pack-year smoking history was referred for evaluation of an abnormal chest radiograph [chest x-ray (CXR)]. Her past medical history was significant for recurrent deep venous thrombosis without any predisposing factors. CXR showed a large mass in the right mid lung and another nodule at the right apex, highly suspicious for a neoplastic process. These were not present on a CXR from 2 years earlier. An fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) scan revealed that all lesions were strongly FDG-avid. Six CT-guided core-needle lung biopsy specimens were obtained from the lung mass and all contained dense, lamellar, or "ropy" keloid-like collagen bundles arranged in a haphazard pattern. The biopsy specimens lacked significant necrosis and granulomas. Congo red stain with polarization was also negative for amyloid. The diagnosis of pulmonary hyalinizing granuloma (PHG) was made. A complete hypercoagulable workup was performed but no underlying abnormalities were found, including a negative lupus anticoagulant and malignancy workup. The patient was maintained on warfarin and followed with serial CT scans for 1 year, with spontaneous regression in the lung mass. The case is unique as it is the first case that reports an association of PHG with recurrent deep venous thrombosis in the absence of autoimmune or procoagulant factors and emphasizes the need for life-long anticoagulation in such scenarios. Also, we report the FDG-avid PET scan findings here that are novel for this disease in adults and add PHG to the list of diseases causing false-positive PET scans when malignancy is suspected.