Aneurysmal Bone Cyst of the Calcaneus

Abstract

Aneurysmal bone cysts (ABCs) are benign, non-neoplastic, expansile, vascular, locally destructive lesions. The lesion may arise de novo (65%) or secondarily (35%) in pre-existing benign or malignant lesions (giant cell tumor, osteoblastoma, chondroblastoma, angioma, and others). The calcaneus is a rare localization for ABC, comprising only 1.6% of the cases. In this paper, we present a case of a female patient with a 3-month history of heel pain that got worse and was accompanied by swelling and difficulty in walking. The magnetic resonance images of the postero-lateral calcaneus showed a contrast-enhanced cystic lesion located in the medullary cavity; exophytic portion of the tumor extended into the soft tissue causing distinctive cortical thinning. Heterogeneous hyperintense septae formations and blood level components were also detected. After correlation with pathology results, the lesion was diagnosed as an ABC. Since an ABC of the calcaneus is a rarely seen phenomenon, we present the radiologic findings in this case and a review of the literature.

Primary tumours of the calcaneus (Review)

“…ABCs in the calcaneus are benign, expansive, locally destructive lesions that account for 1% of all primary bone tumour types ( 18 – 20 ). Of all ABCs, ~30–35% are present in association with another bone lesion including giant cell tumours, osteoblastomas and/or chondroblastomas ( 18 , 19 ).…”

“…A majority of patients with ABC present complaints of heel pain subsequent to minor trauma, discomfort while walking and occasional swelling ( 18 , 19 , 21 ). The heel pain may be chronic, worsening gradually following the trauma ( 19 ). Pathological fractures are rare but have been reported ( 18 ).…”

“…MRI clearly demonstrates an expansile and septate lesion with relatively well-defined margins that contain multiple fluid-fluid levels. The fluid-fluid levels may be best observed on the T2-weighted image with a varying signal intensity due to the chronicity of the associated haemorrhage ( 18 , 19 , 22 ). A BS demonstrates increased uptake at the periphery in a number of cases ( 23 ).…”

“…Upon gross examination, fragments of multiple grey-brown or reddish-brown granular sections contain blood-filled cystic spaces ( 22 ). Histopathologic examination of the lesion reveals cavernous cavities of different dimensions containing fibroblasts, histiocytes and osteoclastic giant cells without any mitosis or atypia ( 19 , 21 , 22 ).…”

“…The choice of ABC treatments ranges from wide resection of the cyst to curettage with bone grafting (Enneking stage 2) ( 12 , 19 ). The use of adjuvants including cryotherapy, phenol, polymethyl methacrylate and irradiation is employed to remove an aggressive lesion (Enneking stage 3) ( 24 ).…”