Moderators: Dr. Christina MacMillan and Dr. Nina Gale
Middle Ear Carcinoid Tumor Metastatic to an Ipsilateral Parotid Lymph Node
Dr. Ben Pilch
Middle ear carcinoid tumor metastatic to an ipsilateral parotid
The submitted slide is a section of parotid gland that contains a tumor almost filling a parotid
lymph node. The tumor is composed of low columnar epithelioid cells in a trabecular architectural
arrangement. The nuclei of these cells contain somewhat prominent nucleoli in a "salt and pepper"
stippled chromatin. Nuclear pleomorphism is only slight, and neither necrosis nor mitotic activity is
present to a significant degree. In areas, the columnar cells surround a core of rounded smaller cells,
some with eccentric nuclei, and with somewhat darker but still stippled chromatin and smaller nucleoli
than those of the larger columnar tumor cells. The tumor has an organoid appearance, and the possibility
of a neuroendocrine neoplasm metastatic to a parotid lymph node presents itself. Immunohistochemical
studies show the tumor cells to be positive for keratin and chromogranin, confirming the diagnosis of a
metastatic low-grade neuroendocrine carcinoma.
The pathologic material from the patient's left middle ear tumor, removed 40 years previously, was
reviewed. The specimen was a bit squeezed, but rounded epithelioid cells in a trabecular arrangement and
with eccentric nuclei were present, similar to the parotid lesion. Immunohistochemical stains were
positive for keratin, chromogranin, and serotonin. The histology and immunophenotype were consistent
with a carcinoid tumor of the middle ear, termed by some middle ear "adenoma" or "neuroendocrine adenoma"
. The patient had experienced a recurrence of the ear tumor 38 years after the original excision and
two years prior to the surgery for the parotid tumor. This tumor also was composed of rounded to
cuboidal cells with eccentric nuclei, focally arranged in a trabecular pattern. The tumor cells were
again immunohistochemically positive for keratin, chromogranin, and serotonin.
These rare middle ear neoplasms are interesting lesions that have engendered a bit of discussion
and some controversy regarding their nature and nomenclature. Lesions similar in histologic appearance
and in clinical behavior have been called both carcinoids and adenomas. Indeed, the advent of
immunohistochemistry has facilitated the appreciation that not only do middle ear tumors labeled
carcinoids exhibit neuroendocrine differentiation, but almost all tumors designated middle ear adenomas
do as well.
These uncommon middle ear tumors are lesions of adults, with a mean age of about 40 years. The
most common symptom is hearing loss, but pain, tinnitus, and other symptoms occur as well. The tumors
are localized middle ear masses that occasionally extend to involve the mastoid air cells and/or external
auditory canal. They often wrap around the ossicles but tend not to invade bone.
Histologically, these tumors exhibit trabecular, glandular, or mixed focally glandular and focally
trabecular architecture and tend to have an "organoid" pattern. They rarely have a solid architectural
pattern. The tumors are composed of epithelial cells with bland cytology and a stippled "salt and
pepper" chromatin. Cytology is bland, and neither necrosis nor an elevated mitotic count is
encountered. Neuroendocrine differentiation is extremely common. In fact, in a large series of 48
cases, Torske and Thompson  found that in 46 of 48 cases, at least one neuroendocrine marker was
"present to a significant degree'", and the other two cases were focally positive for human pancreatic
polypeptide (HPP). Dense core neurosecretory type granules are characteristically seen
ultrastructurally. Among neuroendocrine markers, chromogranin is positive in most cases, and
synaptophysin and serotonin are occasionally positive. Torske and Thompson found HPP to be positive in
93.8% of their cases . The neuroendocrine nature, or differentiation, of the tumor, whether called
carcinoid or adenoma, is so prevalent, that Torske and Thompson have suggested the term "neuroendocrine
But why neuroendocrine adenoma and not carcinoid? Neuroendocrine neoplasms of the bronchi and
lung, larynx, and GI tract are thought to be neoplasms with at least possible malignant potential and are
not called "adenomas", except for endocrine microadenomas of the pancreas.
Much of the rationale for not applying the term "carcinoid" to these tumors is related to their
biologic behavior. These neoplasms have long been considered to be benign. Indeed, the tumors have a
favorable biologic behavior and a good prognosis. Most are cured with excision, and only a relatively
few local recurrences have been reported. However, recent studies have shown that, as in the case
presented here, late metastases to regional lymph nodes can occur. Four cases of middle ear carcinoids
with metastases, including this one, have been reported in the literature to date
agree with Ferlito et al.  that these tumors should be considered potentially malignant, and I feel
that they truly merit the designation of carcinoid tumor of the middle ear.
- Torske KR, Thompson LDR. Adenoma versus carcinoid tumor of the middle ear: a study of 48 cases and review of the literature. Mod Pathol 2002; 15: 543-555.
- Ramsey MJ, Nadol JB Jr., Pilch BZ, McKenna MJ. Carcinoid tumor of the middle ear: clinical features, recurrences, and metastases. Laryngoscope 2005; 115: 1660-1666.
- Ferlito A, Devaney KO, Rinaldo A. Primary carcinoid tumor of the middle ear: a potentially metastasizing tumor. Acta Otolaryngol 2006; 126: 228-231.