Undifferentiated carcinoma of cervical node metastases in patients with an unknown primary lesion: an immunohistochemical study

Sixteen patients with lymphatic metastases to the neck and a histological diagnosis of undifferentiated carcinoma from an unknown primary lesion were assessed using immunohistochemical staining. The results revealed a non-epithelial tumor in 11 cases (malignant lymphoma in 5 cases) and an epithelial tumor in 3 cases. The patients with malignant lymphoma had a good outcome, but those with other non-epithelial tumors did not. Treatment of patients with an unknown primary tumor, especially undifferentiated carcinoma, should be carefully evaluated based on immunohistological examinations to identify malignant lymphoma.