This paper provides a useful tool to assist in determining the diagnosis of benign neoplasms of the temporal bone using readily available imaging modalities. Specifically, this group have looked at chondrosarcoma, an expansile hypermetabolic mass lesion usually found in the squamous part of the temporal bone with middle cranial fossa involvement. They are the first to report on CT, MRI and PET findings in temporal bone chondroblastoma, and did so by retrospective analysis of imaging from five patients from their own institution as well as obtaining imaging from all 11 cases of this tumour reported in the literature, which were reviewed by their team of neuroradiologists in the context of this study. The pathology from the resected specimens was also carefully reviewed to confirm diagnosis. The consistent areas which were identified in these 16 cases of temporal bone chondroblastoma were location, heterogeneity on MRI (low signal intensity on T2-weighted imaging, reflecting the diverse degree of calcification and hemosiderin deposits), interface to the brain, and metabolism on FDG PET, in addition to common symptoms of hearing loss and swelling over the temporal region. The authors outline how these various features can be used to differentiate this slow-growing benign tumour from chondrosarcoma, giant cell tumour, pigmented villonodular synovitis, and primary aneurysmal bone cyst, in an area which is difficult to obtain histological biopsy. Although the sample size involved is small due to the rarity of this lesion, and the slices available from other reports in the literature were limited, this paper has an important role in clinical practice.

Temporal bone chondroblastoma: Imaging characteristics with pathologic correlation.
Park S-W, Kim J-H, Park JH, et al.
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Aileen Lambert

Great Ormond Street Hospital, London, UK.

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