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‘Neuroendocrine’ middle ear adenomas: consistent expression of the transcription factor ISL 1 further supports their neuroendocrine derivation
Author(s) -
Agaimy Abbas,
Lell Michael,
Schaller Tina,
Märkl Bruno,
Hornung Joachim
Publication year - 2015
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.12447
Subject(s) - synaptophysin , neuroendocrine differentiation , pathology , immunohistochemistry , histogenesis , biology , cytokeratin , medicine , cancer , prostate cancer
Aims Neuroendocrine middle ear adenoma ( MEA ) is a rare epithelial neoplasm of uncertain histogenesis that frequently shows neuroendocrine features. To date, <120 cases have been reported. The aims of the current study were to describe our experience with neuroendocrine MEA , to assess the frequency of specific neuroendocrine differentiation, and to test these lesions for transcription factors known to be expressed in a variety of other neuroendocrine tumours. Methods and results We investigated six cases of neuroendocrine MEA , and stained them, for the first time, for the transcription factors CDX 2, TTF 1, PAX 8, and ISL 1 (islet‐1). The patients were four men and two women (mean age, 39 years; range, 27–53 years). Two of four patients with extended follow‐up (4.5–22 years) experienced recurrence at 92 months, and at 9 and 22 years, respectively. One case extending into the external ear coexisted with cholesteatoma. Histological examination showed trabecular, solid, acinar, glandular, cribriform, organoid, nested, diffuse non‐cohesive plasmacytoid and pseudoalveolar patterns in varying combinations. Immunohistochemistry showed consistent expression of vimentin (4/4), pancytokeratin (6/6), synaptophysin (6/6), CD 56 (4/4), and ISL 1 (6/6). A CK 7 antibody stained scattered cells in two of five cases. The myoepithelial markers and transcription factors TTF 1, CDX 2 or PAX 8 were not expressed in any of the cases. Conclusions Middle ear adenoma is an indolent, locally recurring, but generally non‐metastasizing neoplasm with uniform expression of synaptophysin and ISL 1, indicating true neuroendocrine differentiation. Because of its highly varied cellular and architectural appearance, MEA should be distinguished from tympanic paraganglioma and a variety of rare benign and malignant lesions at this site.