Papillary endolymphatic sac tumors: Imaging findings

Purpose: To present (he CT, MR imaging, and angiographie findings in 20 paliems with papillary endolymphatic sac tumors (PELST). Materials and Methods: The clinical and imaging studies in 20 patients with a histological diagnosis of PELST were retrospectively reviewed. All patients underwent a combination of CT ( 18/20). MR imaging ( 15/20) and angiography ( 12/20). CT studies were evaluated for bone erosion, and central and peripheral calcification. MR imaging was evaluated for Tl W and T2W signal intensity, enhancement patterns, and presence of flow voids. Review of the angiographie studies determined blood supply to the tumors. Results: CT showed all tumors to be destructive and to contain intratumoral calcifications centered in the retrolabynnthine region. MR imaging appearance varied with the size of the lesion. 12/15 (80%) tumors demonstrated increased T1W signals. The location of this high signal was circumferential in small lesions (mean diameter < 3 cm) and scattered throughout the lesion in advanced tumors. Flow voids were only seen in tumors with mean diameters > 2 cm. The blood supply arose predominantly from the external carotid artery (ascending pharyngeal artery [ 12/12|. and stylomastoid artery 112/12]). Large tumors had additional supply from the internal carotid and posterior circulation. Conclusions: PELST are destructive hypervascular lesions that arise from the retrolabyrinthine region of the temporal bone. Increased Tl W signals on nonenhanced MR imaging are commonly present and may help distinguish these lesions from other more common aggressive tumors that involve the temporal bone.