Radiological findings of retroauricular dermoid with intra-calvarial extension

Abstract

Dermoid cysts are rare in head and neck region. A dermoid cyst arising in the retroauricular region over the mastoid can be easily misdiagnosed as a lymph node, thus posing significant diagnostic challenges. We present a case report of two year old boy with retroauricular dermoid showing intracalvarial extension. The child presented with the swelling in the right retro-auricular region with no associated hearing loss, tinnitus or vertigo. Provisional diagnosis clinically made was that of a large necrotic post auricular lymph node. On ultrasonography, well defined heterogeneous hypoechoic lesion showing few hyperechoic areas with scalloping and extension into the underlying temporal bone. On computed tomographic scan, heterogeneous non enhancing lesion showing areas of negative attenuation value seen in retroauricular region with extension into the temporal bone. Final diagnosis was confirmed by histopathological examination of the surgically resected specimen.