[Metastatic carcinoma of the neck from unknown primary sites]

Encountering a metastatic carcinoma of the neck from an unknown primary site is not unusual, despite intensive examinations of the entire body. In previous reports, the pathological diagnosis of these carcinomas was usually squamous cell carcinomas and rarely adenocarcinoma. We treated eight patients with metastatic carcinoma of the neck from unknown primary sites, including 4 cases of squamous cell carcinoma, 2 cases of adenocarcinoma, one case of small cell carcinoma, and one case of clear cell carcinoma, during a 10-year period from January 1992 to December 2001. We clinically examined these eight cases, and focusing on the two cases of metastatic cervical adenocarcinoma from unknown primary sites. The 8 cases consisted of 5 cases of N2 and 3 cases of N3 disease. Three of the 5 N2 patients underwent a neck dissection, but all three of the N3 cases were judged to be inoperable. Disease-free survival was achieved in all 3 patients who underwent surgery. In this paper, we review 36 reports on metastatic carcinomas of the neck from unknown primary sites and statistically analyze 1454 cases. Pathologically, the majority of them (81.1%) were squamous cell carcinoma; adenocarcinomas accounted for only 7.6% of the cases. Notably, 65.0% of the patients with cervical metastatic adenocarcinomas were confirmed to have primary lesions outside the head and neck region. The prognosis of primary unknown metastatic cervical adenocarcinoma is reportedly poor, and the optimal treatment is still unclear, although surgery is recommended for primary unknown metastatic cervical squamous cell carcinoma. However, we suggest that intensive treatment, including surgery, radiotherapy, and chemotherapy, of metastatic lesions of the neck may play a key role in improving patient prognosis.