Aneurysmal bone cyst of the second metatarsal: three-phase bone scan findings and radiological assessment.

Hellenic Journal of Nuclear Medicine ñ September December 2008 To the Editor: Aneurysmal bone cysts (ABC), are usually located in the long bones and the spine and have a benign pathology [1, 2]. ABC are mainly diagnosed in infants, children and young adults. Pain and/or pathological fractures are the most common findings [1-3]. A rare location for ABC is metatarsal bone and few such cases occurring in children have been reported in the literature [4-6]. We have studied an ABC of the second metatarsal bone in a 15 years old boy who was admitted to the hospital with a persistent, progressive pain and gradually increasing swelling in the left foot, during the last year. There was no history of trauma. Clinical examination revealed diffuse swelling and tenderness of the left foot. Routine laboratory analyses were all normal. Plain radiograph of the left foot revealed an osteolytic and markedly expansive lesion in the second metatarsal bone (Fig. 1A). Computed tomography (CT) (Fig. 1B) and magnetic resonance (MR) (Fig. 1C) images showed a large well-defined cystic lesion with thin cortex and internal septa, in the second metatarsal bone. A three-phase bone scan was performed after the intravenous injection of 740 MBq technetium-99m methylene diphosphonate (99mTc-MDP). The blood-flow (Fig. 2A), blood-pool (Fig. 2B) and delayed images (Fig. 2C, D) showed increased vascularity and increased radiotracer accumulation in the left second metatarsal bone. The delayed lateral image demonstrated the characteristic doughnut sign [3] with moderately increased radiotracer accumulation at the periphery of the lesion, that may be due to hyperemia and little activity in its center (Fig. 2D). The patient underwent surgery. The lesion Correspondence