Dehiscent Jugular Bulb

Findings:

A well circumscribed multilobulated zone of scalloping is present in the left temporal bone which is contiguous with the jugular bulb. On modified reconstructions, there is absence of bone margin at the hypotympanum.

Differential Diagnosis/Discussion:

The differential diagnosis for a lytic lesion involving the temporal bone is broad. Contiguity with the jugular bulb and the smooth bone scalloping indicates that this is a vascular finding and not a neoplasm. A prominent jugular bulb may simulate the presence of glomus tumor on MR, therefore CT is often helpful to distinguish bone margins. Permeative irregular bone destruction would be expected with a glomus tumor. Other cause such as metastatic disease would be expected to have more irregular margins.

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