Superscan caused by renal osteodystrophy: Observed on 18F FDG PET/CT scan

Abstract

Superscans have been described in variety of conditions such as metastatic disease, metabolic bone disease, and myeloproliferative disorders. We describe a rare case of supercan from metabolic bone disease/renal osteodystrophy observed on F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scan. A 35-year-old woman patient with history of human immunodeficiency virus (HIV), end stage renal disease, and recently diagnosed with breast carcinoma had undergone neoadjuvant chemotherapy followed by mastectomy with sentinel lymph node dissection and adjuvant chemoradiation. The patient has been in remission for the last 10 years of follow-up visits. She was subjected to F-18 FDG PET/CT scan and Tc-99m methylene diphosphonate (MDP) bone scan 2 weeks apart for initial staging workup of locally advanced ductal carcinoma of the right breast. Whole body F-18 FDG PET/CT scan [Figure 1a and b] apart from radiotracer uptake in the primary neoplasm in the right breast, demonstrated diffusely increased FDG uptake in the osseous structure without any abnormalities on corresponding CT scan and absence of radiotracer excretion in the kidneys and urinary bladder. Subsequent Tc99m MDP bone scan [Figure 2] demonstrated classic findings of super scan of diffuse, uniform radiotracer uptake in the axial and appendicular skeleton, faint visualization of soft tissue, and absence of radiotracer excretion in the kidneys and urinary bladder.[1] As both bone scan and F-18 FDG PET/CT scan demonstrated diffuse uniform radiotracer uptake in osseous structure indicative of metabolic bone disease rather than patchy, heterogeneous radiotracer uptake observed with skeletal metastasis and corresponding CT scan images being unremarkable, skeletal metastasis was felt less likely.