Extraosseous Tc-99m methylene diphosphonate concentration in the forearm following post-mastectomy lymphatic obstruction
A 42-year-old female patient with a history of right breast cancer reported recent onset swelling of the right forearm. She had undergone modified radical mastectomy 2 years previously, with subsequent chemotherapy and radiotherapy. A routine whole-body bone scan was performed to assess any skeletal involvement. Following intravenous injection of 740 MBq (20 mCi) of Tc-99m MDP, imaging was performed after 3 hours under a dual head gamma camera (Ecam, Siemens, Germany) fitted with a low-energy high-resolution collimator. Diffuse soft tissue uptake of tracer in the right forearm, extending to the right elbow was noted []. No bony abnormality was detected.\nA provisional diagnosis of lymphatic obstruction in the right upper limb was made and lymphoscintigraphy was performed during the patient's next visit, 7 days later. Unfiltered Tc99m-sulphur colloid (20 MBq) was injected intradermally into the second and third web spaces of each hand, and whole body images were acquired after 10 min and 2 hours under the same gamma camera, with the arms raised above the head. The 10-min image showed rapid movement of tracer into the left trochlear and axillary lymph nodes, with minimal tracer movement in the region of the distal right forearm. The delayed image showed diffuse soft tissue concentration of tracer only in the distal part of the right forearm, with no further ascent, indicating lymphatic obstruction [].