Arterial pseudoaneurysm as a false positive for infection in bone scintigraphy and with labeled leukocytes in a patient with total hip prosthesis Pseudoaneurisma arterial como falso positivo de infección en la gammagrafía ósea y con leucocitos marcados en un paciente con prótesis total de cadera

In 2010, an 81-year-old woman had a total left hip replacement for severe coxarthrosis. Thereafter, she presented with pain and swelling on the lateral and medial side of the left thigh. On clinical suspicion of prosthetic mobilization, the patient was referred to the Department of Nuclear Medicine for three-phase bone scan with 99mTc-HDP (740MBq). In the vascular and tissue phase a focal increase of tissue pool was observed in the proximal and medial third of the left thigh (Fig. 1A). The delayed phase showed heterogeneous uptake in the proximal femoral diaphysis with a focal increased uptake on the external lateral margin (Fig. 1B). To rule out infection a scan with autologous leucocytes labeled with 99mTc-HMPAO (740 MBq) was performed showing intense leucocytes accumulation concordant with that observed in the early phase of the bone scan, being related to a soft-tissue abscess (Fig. 1C). Magnetic resonance was carried out showing a large fluid collection with a spontaneous high intensity T1-weighted sequence