Primary aneurysmal bone cyst of talus
A 20-year-old male, student by occupation, presented to the outpatient department of Government Medical College, Jammu, India in December 2009 with complaints of insidious onset, intermittent dull aching pain in the left ankle, since last 7 months. He denied history of swelling, fever, chills, sweats, weight loss or similar complaints in other joints of the body. There was no history of recent or remote trauma. The family, drug, occupational, sexual and recreational histories were non-contributory. General physical examination was unremarkable. On examination of the foot, there was no visible or palpable swelling, local temperature was normal and tenderness to deep palpation was noted on the dorsal aspect of ankle. The distal neurovascular status was normal.\nSerum biochemistry studies were normal. Anteroposterior (AP) and lateral radiographs of the ankle [] and a Computed Tomography (CT) Scan [] revealed a radiolucent, expansile, lytic lesion with lobulated borders occupying the head and neck of the left talus. No periosteal reaction or calcifications were noted. Gadolinium enhanced Magnetic resonance Imaging (MRI) of the foot and ankle revealed an eccentric, cystic lesion in the left talus, which was hypo-intense on T1 weighted sequences and hyperintense on T2 weighted sequences and showed localized cortical erosion. The lesion showed subtle enhancement with gadolinium. There was no extension into the subtalar joint or adjacent soft tissues [].\nCT guided fine needle aspiration from the lesion revealed numerous osteoclast giant cells in an hemorrhagic background.\nOn the basis of the clinical findings, imaging studies and cytological examination a provisional diagnosis of giant cell lesion of bone was made. We considered giant cell tumor, aneurysmal bone cyst and simple bone cyst amongst the diagnostic differentials. However, we decided to plan the treatment of the lesion along the lines of giant cell tumor. The nature of the lesion, the diagnostic differentials, different treatment options and possible outcomes were discussed at length with the patient prior to obtaining an informed and written consent.\nThe patient was taken up for extended intra-lesional curettage with phenol as an adjuvant and autologous iliac crest bone grafting. The talus was exposed by the standard antero-lateral approach to the ankle. Per-operatively, cortical erosion on the lateral aspect of the talar head and neck could be identified. A window was made on the lateral surface of the talar neck to facilitate curettage. The interior of the talus revealed presence of a spongy, blood filled mass. Thorough curettage was performed and the cavity was enlarged in all directions using a high speed burr and phenol was used as an adjuvant. Finally, the ensuing cavity was packed with autologous cancellous iliac crest graft.\nPost-operatively, the foot was immobilized in a non weight bearing below knee cast for 12 weeks.\nHistopathological examination of the curettage material revealed presence of multiple blood filled cavities enclosed by fibrous septae without an endothelial lining []. Numerous osteoclast giant cells arranged irregularly in clusters, as well as scattered individually were also identified. A diagnosis of primary aneurysmal bone cyst was made.\nRadiographs at 12 weeks showed good incorporation of the bone graft after which patient was permitted to bear weight []. Initially, the patient had restriction of dorsiflexion, which improved completely with physiotherapy. There was no recurrence after two years of follow-up.