Primary carcinoid tumor in the external auditory canal

Area of Science:

• Otolaryngology
• Oncology
• Pathology

Background:

• Neuroendocrine neoplasms (NENs) are rare in the external auditory canal (EAC).
• Distinguishing primary EAC NENs from metastatic tumors is crucial for diagnosis and management.
• This case presents a unique instance of a primary NEN in the EAC.

Purpose of the Study:

• To report a rare case of a primary neuroendocrine neoplasm in the external auditory canal.
• To describe the clinical, imaging, and histopathological findings of this rare tumor.
• To contribute to the limited literature on primary EAC NENs.

Main Methods:

• A 39-year-old male patient presented with a year-long hearing disturbance.
• Temporal bone computed tomography (CT) revealed a mass obliterating the left EAC.
• Histopathological examination showed sheets of round tumor cells with specific immunohistochemical markers (CD56+, synaptophysin+, chromogranin-, CK7-, CK20-).

Main Results:

• The tumor was diagnosed as a well-differentiated neuroendocrine carcinoma, grade 1 (G1), according to WHO classifications.
• The Ki-67 proliferation index was low (<2%), with no observed mitosis or necrosis.
• The patient remained disease-free for 20 months post-diagnosis, with no local recurrence or metastasis.

Conclusions:

• Primary neuroendocrine neoplasms of the EAC are exceedingly rare, with only six cases previously reported.
• This case underscores the importance of considering metastatic tumors in the differential diagnosis.
• Further research is needed to clarify the prognosis and optimal treatment strategies for these rare tumors.