Low-Grade Adenocarcinoma of Probable Endolymphatic Sac Origin

Background

The low-grade adenocarcinoma of probable endolymphatic sac origin is also known as aggressive papillary middle ear tumor. It is a very rare neoplasm arising within the endolymphatic system of the inner ear. In spite of its rarity, these tumors have a peculiar association with another rare disease, von Hippel-Lindau disease, especially bilateral tumors. These tumor grow slowly leading to symptoms of tinnitus or vertigo. In time, the tumor may be locally aggressive and may lead to lytic lesions in the temporal bone. These tumors have a broad age distribution ranging from 15-71 years (mean 41 years) occurring equally in both sexes.

Under the microscope, these tumors have a papillary-glandular appearance with papillae lined by a single row of bland cuboidal cells. Clear cell changes may be present. The cystic spaces often contain pink colloif-like material, simulating thryoid follicles. The tumor is strongly positive for cytokeratin and variably positive for S-100, GFAP, and synaptophysin.

DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES

Metastatic papillary carcinoma of the thyroid Thyroglobulin positive
Characteristic cytology with nuclear grooves, pseudonuclear inclusions, ground glass nuclei

Metastatic renal cell carcinoma Negative for GFAP and synaptophysin
Only 2% positive for S-100

Am J Surg pathol 1988;12:790-797
Cancer 1989;64:2292-2302.
Rosai J. Ackerman's Surgical Pathology. Eight Edition. Mosby 1996.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.

Commonly Used Terms

Ear
von Hippel-Lindau disease

Last Updated 11/29/2001

DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
Metastatic papillary carcinoma of the thyroid	Thyroglobulin positive Characteristic cytology with nuclear grooves, pseudonuclear inclusions, ground glass nuclei
Metastatic renal cell carcinoma	Negative for GFAP and synaptophysin Only 2% positive for S-100