The radiologic diagnosis of endolymphatic sac tumors

To identify and classify radiologic criteria for the diagnosis of endolymphatic sac tumors.

Retrospective case review. Tertiary referral center.

31 adult patients (32 tumors) with imaging (computed tomography [CT], magnetic resonance imaging [MRI], and/or angiography) and histopathologic diagnoses of lesions that involved the posterior temporal bone from July 1995 to August 2004 were included in the study. Interventions were diagnostic. Main outcome measures were CT, MRI (T1, T1 with gadolinium enhancement and T2-weighted), and angiographic features of seven patients (eight temporal bones) with endolymphatic sac tumors were examined and compared to the radiologic findings of the 24 historical control patients with various lesions involving the posterior temporal bone.

CT findings of endolymphatic sac tumors revealed lesions centered over the endolymphatic sac, retrolabyrinthine, and presigmoid regions of the temporal bone. Central calcific spiculation and posterior rim calcification was present in all lesions (100%) on CT examination. T1-weighted MRI scans showed hyperintense foci in seven of eight lesions (88%). T1-weighted post-gadolinium scans showed heterogeneous enhancement in all cases (100%). T2-weighted images showed heterogeneous signals in all lesions (100%). Angiography (traditional or magnetic resonance angiography [MRA]) identified exclusive external carotid supply for lesions less than 3 cm. Tumors greater than 3 cm were supplied by external carotid, internal carotid, and posterior fossa circulation arteries.

Reliable radiologic criteria to preoperatively identify endolymphatic sac tumors exist. Preoperative diagnosis of posterior temporal bone lesions enables appropriate surgical planning and treatment of the pathology.