A 42-year-old female was admitted with complaints of a 15-day history of intermittent headaches and dizziness, without nausea and vomiting. Computed tomography (CT) revealed a giant mass lesion with mixed density in the right CPA region along with the destroyed petrous bone (Figure 1A), and a low density space-occupying lesion in the left cerebellar hemisphere. No abnormal physical and laboratory examination including abdominal CT, were found except for a past history of appendicitis excision and cesarean section and the impairment of right hearing resulting from otitis media in childhood. Cranial magnetic resonance imaging (MRI) described two tumors that were 4 × 3 × 3 cm in size in the right CPA region with mixed-signal intensity on T1, T2-weighted images and heterogeneous contrast enhancement; and 4.1 × 2.5 × 3.0 cm in size in the left cerebellar hemisphere with being obviously cystic change (Figure 1B-E). The boundary of two lesions were relatively clear from surrounding parenchyma.Open in a separate windowFigure 1Radiologic characterization of endolymphatic sac tumor and hemangioblastoma. A: CT imaging demonstrated a destroyed petrous bone involving the right mastoid and the middle ear. B-E: MR scan showed two giant masses co-existing in the posterior cranial fossa. The right one in the CPA was irregular, heterogeneous on T1/T2-weighted images as well as heterogeneous contrast enhancement, the left lesion was shown with solid and cyst change in cerebellar hemisphere. F: MRI scan after the second operation showed totally resection of both lesions.Operation and pathological findingsBoth tumors were completely removed via right and left retrosigmoid sinus craniotomy respectively within 25 days. During the first operation, lesion with demarcating from normal cerebellar tissue and invading part of petrous bone were found. The origin of the tumor from petrous bone could be apparently observed. In the second operation, the brown cyst fluid associated with old hemorrhage and soft solid nodule were seen. Under a microscope observation after the first surgery, intense vascularization of the tumor and the obviously primarily cystic architecture were observed. The cystic architecture filled with colloid-like material. Most of them were lined by a single layer of flattened epithelial cells, few covered by a single layer of cuboidal to columnar cells (Figure 2A-D). Immunohistochemical staining demonstrated vascular cells positive reactivity for CD31 (Figure 3A) and CD34 (Figure 3C), which were mistaken for the tumor cells at the initial diagnosis. Subsequently, further immunohistochemical staining showed positive reactivity for PAS (Figure 3B), epithelial membrane antigen (EMA) (Figure 3D), NSE and cytokeratin (CK) but negative for D2-40 and S-100. As to another specimen, histological examination shown round-to-oval nuclei and abundant clear cytoplasms in most of cells (Figure 4). Immunohistochemical staining confirmed hemangioblastoma.