Atypical carcinoid tumor of the larynx. A light microscopic and ultrastructural study.

A 68-year-old man had an 11-year history of a recurring carcinoid tumor of the larynx. In six additional examples of this uncommon neoplasm, cervical lymph node metastases were present in four patients and osseous involvement developed in another. Two patients died of their disease, one died without evidence of neoplasm, and four were living and clinically free of tumor at last follow-up. Laryngeal carcinoids are often atypical histologically and may be misdiagnosed as undifferentiated carcinoma, prompting inappropriate radiation therapy for a radiation-resistant neoplasm. Histologic features suggestive of carcinoid include a nesting or trabecular growth pattern and prominent perineural invasion. Argyrophil stains were positive in four of five cases. Ultrastructurally, these neoplasms have abundant dense core granules.