Contrasting behavior of endolymphatic sac tumors: a report of 2 cases and literature review

Case Series and Systematic Review of Radiation Outcomes for Endolymphatic Sac Tumors

OBJECTIVE

Surgery is the primary treatment modality for endolymphatic sac tumors (ELST). Two case examples are presented to highlight some rare instances when radiation therapy may be used. The outcomes following radiation therapy for ELST are controversial. This report systematically reviews those outcomes and compares results between external beam radiation and stereotactic radiosurgery.

DATA SOURCE

In accordance with PRISMA guidelines a systematic literature search of the Ovid Medline, Embase, Scopus, Cochrane library, and clinicaltrails.gov databases was performed in August 2017.

STUDY SELECTION

Twenty-two studies met inclusion criteria and report ELST outcomes following radiation therapy. Additional data on tumor size, previous surgery, radiation modality, and radiation dosing was collected.

DATA EXTRACTION

The methodological quality was independently assessed by three reviewers. The included studies were small, heterogeneous case reports with a low level of evidence, and several sources of bias.

DATA SYNTHESIS

The primary outcome was tumor control following radiation, defined as no growth. A comparative analysis of external beam versus stereotactic radiation was performed.

CONCLUSION

Forty-six tumors from 42 patients were independently analyzed. The overall tumor control rate was 67.4%. When analyzing patients in which tumor was present at the time of radiation, external beam radiation controlled 9 of 19 tumors (47.4%) while stereotactic radiosurgery controlled 14 of 18 tumors (77.8%). The effect size of 30.4% favors stereotactic radiosurgery, but the wide confidence interval (-4.4 to 57.4%) limits what conclusions can be drawn. Radiation for ELST remains controversial and more long-term data is needed.

Endolymphatic Sac Tumor in Two Dogs

Endolymphatic sac tumors (ELSTs) are rare neoplasms of the inner and middle ear described in humans. Diagnosis of such neoplasms is difficult and largely dependent on a combination of histologic, immunohistochemical, and clinical findings. Although the neoplastic cells lack cellular features of malignancy, these are clinically aggressive tumors that often invade the surrounding temporal bone. Here, we describe 2 dogs with middle ear masses that share morphologic, immunohistochemical, and clinical similarities with human ELSTs. Advanced imaging of the masses revealed evidence of aggressive behavior such as bony lysis of the temporal bone. Histologically, the neoplastic epithelial cells formed papillary structures, lacked mitotic figures, and had mild anisocytosis and anisokaryosis. The neoplastic cells were immunohistochemically positive for cytokeratin AE1/AE3 but were negative for chromogranin, synaptophysin, and thyroglobulin. Local invasion and bone destruction but no evidence of metastases suggest a clinical behavior similar to human ELSTs.

Endolymphatic sac tumors : report of four cases

Endolymphatic sac tumor is rare, locally aggressive hypervascular tumor of papillary structure, arising from the endolymphatic duct or sac in the posterior petrous bone. We present four cases with this tumor. Two patients were male and the other two were female. Age of each patient was 15, 52, 58, and 67 years. Three patients presented with progressive hearing loss and sustained vertigo for months to years and another one was referred for the tumor detected in routine medical check-up. Preoperative embolization was performed in 3 patients. Complete excision of the tumor was achieved in all patients using translabyrinthine or retrosigmoid approach. Herein, we describe the clinical and radiographic features, surgical treatment and pathologic findings with a review of the literature.