Radiographic findings of patient 3. (Top left) Magnetic resonance imaging (MRI), axial cut, T1-weighted with gadolinium contrast, shows 6-cm cauliflower-like enhancing tumor in the left posterior fossa with extensive invasion along the length of the petrous temporal bone from the petrous carotid artery anteromedially to the sigmoid sinus and cranium posterolaterally. (Top right) MRI, coronal cut, T1-weighted with gadolinium contrast demonstrates significant protrusion medially with compression and midline shift of cerebellum, brainstem, and fourth ventricle. (Bottom left) Computed tomography (CT), axial cut, bone window of the left temporal bone shows substantial bony erosion along the entire posterior face of the petrous temporal bone, with complete destruction of the operculum and bony vestibular labyrinth, and soft tissue extension into the mesotympanum. (Bottom right) Angiogram, cannulation of left external carotid artery, pre- embolization shows sizable tumor blush off of the occipital and ascending pharyngeal arteries. There was no vascular contribution off of the internal carotid or vertebrobasilar systems (not shown). 

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... magnetic resonance venography [MRV]) presentation was remarkable for extensive destruction of the lateral skull base and demonstration of a massive gadolinium-enhancing lesion centered on the left temporal bone and extending intra- cranially with medial displacement and compression of the cerebellum, brainstem, and fourth ventricle; superior extension into the middle fossa and enveloping the superior petrosal sinus; inferior extension into the jugular foramen; and thrombosis and loss of flow in the left transverse and sigmoid sinus. Fig. 2 demonstrates the preoperative appearance of this patient’s tumor, as seen on MRI, CT, and angiography. Of interest is the similarity in presentations of patients with true ELSTs and those with sac pseudotumors. As seen in Table 1, there is no obvious distinction in clinical presentation differentiating patients with true tumors from those with pseudotumors. These pseudotumors also mimicked true neoplasms radiographically, and only intraoperatively was there a suggestion of differences between the two. Patient A demonstrated erosion of the petrous bone behind the internal auditory canal (IAC) and into the vestibule and semicircular canals on CT, with MRI revealing a 2-cm gadolinium- enhancing mass posterior to the IAC with extension into the labyrinth and labyrinthine enhancement. Intraoperative identification was made of a fibrous lesion eroding the semicircular canals and vestibule, and labyrinthectomy and skeletonization of the IAC were performed to completely resect the lesion. Frozen section histological examination revealed only dense fibrous tissue, and final histopathological diagnosis confirmed a benign endolymphatic sac containing only dense fibrous tissue and foci of chronic inflammation. Patient B also demonstrated scalloped bone erosion along the operculum and posterior petrous face on CT, with MRI showing a gadolinium- enhancing lesion filling the extent of the endolymphatic sac along the posterior petrous apex and abutting the labyrinth. Fig. 3 presents the CT and MRI radiographic findings in this patient, which are also representative of those of Patient A. A fibrous lesion was found along the posterior fossa dura encroaching on but not invading the labyrinth, and therefore a hearing conservation approach was used. The lesion infiltrated extensively posteriorly onto the sigmoid sinus, and a transjugular approach, with resection of the posterior fossa dura and sigmoid sinus, was necessary for complete resection. Final histology showed a diffuse inflammatory in- filtrate within a normally appearing endolymphatic sac, without epithelial proliferation or papillary or cystic cytoarchitecture. Table 2 details the treatment approaches and outcomes for our patient cohort. With regards to treatment, all five patients underwent primary surgical resection of their lesions. The approaches for patients 1, 2, 3, and A were hearing ablative as all presented with hearing loss and all had tumor eroding the bony labyrinth. In addition, patients 3 and A had nonserviceable hearing. Patient B presented with normal hearing and intact otic capsule intraoperatively, and hearing was preserved with unchanged thresholds and speech discrimination postoperatively. All patients had gross total resection of tumor, with patient 3 retaining microscopic residual attached to the neural structures of the medial jugular foramen and encasing the internal carotid artery at the completion of surgery. Fig. 4 illustrates the papillary-cystic nature of this patient’s tumor, representative of the general histological appearance of ELSTs. All patients with true ELSTs received adjuvant radiotherapy, with patients 1 and 2 receiving fractionated external beam radiotherapy and patient 3 receiving proton beam therapy. All patients are alive at the time of manuscript submission. Follow- up intervals range from 10 to 144 months, with the three tumor patients under routine surveillance with MRI. Following evaluation of our group’s patients, we reviewed all case series in the English literature of three or more patients with ELSTs. 5–11 Seven eligi- ble studies reported sufficient patient information regarding specific treatments, follow-up periods, and survival characteristics—no evidence of disease (NED), alive with disease (AWD), died of disease (DOD), or died of other cause (DOC)—to be included in the analysis, and to this we added the results of our present study. Table 3 summarizes demographics, tumor characteristics, management, and treatment outcomes reported for each of these studies. These eight groups comprised 49 cases. Study periods ranged from 11 to 39 years, with two articles presenting compilations of VHL patients having undergone hearing conservation surgery without specifying incidence reporting period. 10,11 Patient ages at the time of presentation or treatment ranged from 17 to 75 years, although most patients clus- tered in the 30- to 50-year age group. There was a gender bias, with two thirds of the patients being women and one third of them men. Twelve patients, or 24%, had VHL, but this variable was not controlled in our analysis and incidence is heavily biased from the two compiled studies of VHL patients undergoing hearing conservation surgery. Reported follow-ups were highly variable and ranged from 0 to 261 months. Reported tumor sizes ranged from 0.5 to 6.0 cm, with only half of the studies reporting. Hearing loss was the most common reported presenting symptom, occurring in nearly every reported patient. The most commonly involved nerve was the facial nerve, with preoperative facial paresis or paralysis in 43% of patients. In patients with larger tumors or in those who delayed presentation for decades after onset of initial symptoms, multiple cranial neuropathies were present including trige- minal (five patients) and glossopharyngeal/vagal nerves (five patients). Surgical resection was the primary modality of treatment in all but one patient, with adjuvant radiotherapy applied in 14 patients (29%). Two thirds of patients underwent hearing ablative surgical approaches, whereas the remaining one third underwent hearing conservation surgery. Of these, nine patients had VHL and had their tumors diagnosed relatively earlier secondary to surveillance audiometry. Total tumor resection was achieved on initial surgery in 40 patients. The remaining nine patients with subtotal tumor resection were divided into two groups. One patient each from three groups had massive tumors larger than 5 cm with significant cranial nerve and vascular involvement, making total resection without significant functional impairment impossible. 8,9 Six patients from one study underwent planned subtotal resection with postoperative radiotherapy. 5 Overall survival characteristics were 74% NED, 20% AWD, and 4% DOD. Within all groups, two patients died of disease within the reporting period. One patient died of esophageal bleeding during the course of palliative radiation therapy for presumed metastatic renal cell carcinoma to the skull base. The second patient presented with four prior subtotal resections of presumed paraganglioma followed by 54-Gy radiotherapy. The patient had a 5.5-cm recurrent ...