Non-osseous uptake on Tc99m methylene diphosphonate in multiple muscles confirmed on SPECT/computed tomography

Abstract

A 55-year-old female presented with complaints of pain in the left hip radiating to the left lower limb since 1 year. Computed tomography (CT) abdomen and pelvis revealed bony destruction of pubic symphysis with associated soft tissue component suspicious of infective or metastatic etiology. Magnetic resonance imaging Lumbo-sacral spine performed later revealed altered bone marrow signal in sacral 1-3 vertebrae. Wholebody bone scan with 25 mCi of Tc-99m methylene diphosphonate (MDP) was performed, which revealed multiple skeletal metastases and extraosseous soft tissue uptake was seen involving multiple muscles. We performed single photon emission tomography single photon emission computed tomography (SPECT)/computed tomography (CT) images to precisely delineate the muscle involved and noted calcification on CT images in one of the muscle at site of Tc-99m MDP uptake, no definite calcification was noted in the other muscles. Thus, the final diagnosis was multiple skeletal metastasis with metastatic calcification in multiple muscle from an unknown primary.