Asymmetrically increased rib cage uptake on bone scintigraphy: Incidental detection of pleural mesothelioma on single photon emission computed tomography/computed tomography
A 50-year-old female patient of carcinoma left breast underwent modified radical mastectomy, followed by radiotherapy 12 years back. She now presented with left-sided chest pain since 3 months. Suspecting the pain to be of musculoskeletal origin, the treating oncologist referred the patient for 99mTc-MDP BS to rule out skeletal metastases. BS was done 3 h, following intravenous injection of 20 mCi of 99mTc-MDP. It revealed diffusely increased radiotracer uptake involving all the left-sided ribs thus giving the appearance of asymmetrically increased left rib cage uptake [Figure and ; arrows]. The remaining skeleton showed normal radiotracer distribution. Because this pattern was atypical for rib metastasis, single photon emission computed tomography/computed tomography (SPECT/CT) of the thorax was done in the same setting. Transaxial SPECT and SPECT/CT images [Figure and ; arrows] revealed diffusely increased radiotracer uptake in all the left-sided ribs. Using bone window on CT [], all the left-sided ribs showed regular cortical outlines with no apparent abnormality. Transaxial CT in soft tissue window revealed circumferential nodular left-sided pleural thickening [; arrow, arrow head]. The increased uptake of tracer in the ribs was likely secondary to the increased vascularity in underlying pleural pathology and was interpreted as reactive in nature. Biopsy from the pleural-based nodular lesion was suggestive of pleural mesothelioma [Figure -]. Patient was referred to the oncology department for further work up.