The clinical importance of cystic squamous cell carcinomas in the neck: a study of 136 cases.

BACKGROUND: Predominantly cystic squamous cell carcinomas in the neck often present without a clinically apparent primary and therefore are frequently considered to be of branchial cleft origin. It is the authors' hypothesis that the anatomic site of the primary carcinoma that produced the neck metastasis can often be predicted on the basis of the histologic features.
METHODS: Cases of cystic squamous cell carcinoma in the neck diagnosed between 1971 and 1991 were retrieved from the Otorhinolaryngic Pathology Registry of the Armed Forces Institute of Pathology. Histologic features were reviewed and patient follow-up was obtained and analyzed.
RESULTS: In cases wherein the primary site was discovered subsequently, 64% of the primaries were in the lingual or faucial tonsil. An additional 8% of cases were in nasopharyngeal tonsillar tissue. The cases that did not originate in Waldeyer's tonsillar ring generally differed in histologic appearance from the tonsillar cases. The tonsillar primaries were discovered within an average of 12.4 months, but many were not discovered for years (up to 11 years). Most were small, indicating a slower growth of the primary than is usually expected for squamous cell carcinoma. Patients with such carcinomas had a much better prognosis than patients with metastatic squamous cell carcinomas of other upper airway mucosal sites.
CONCLUSIONS: In most cases of prominently cystic squamous cell carcinomas in the upper neck, the origin of the primary site will be in faucial or lingual tonsillar crypt epithelium. Knowledge of the probable site of origin allows for more tailored therapy in which the patients can be treated relatively conservatively with surgical excision and subsequent field-limited radiation therapy only, with 77% survival at 5 years. None of the cases reviewed in this study was a branchiogenic carcinoma.