¹⁸F-FDG PET/CT for the detection of primary malignancy in patients with cervical lymph node metastases from unknown origin

Objective: To investigate the value of ¹⁸F-FDG PET/CT for the detection of primary malignancy in patients with cervical lymph node metastases from unknown origin. Methods Seventy-eight patients (48 males, 30 females, average age (56.4± 14.7) years) who were diagnosed as cervical lymph node metastases from unknown origin by fine needle aspiration underwent ¹⁸F-FDG PET/CT from 2007 to 2012. ROI was drawn with SUV_max calculated. The distribution of the lymph nodes was classified according to the standard levels Ⅰ to Ⅵ, as well as the retropharyngeal and supraclavicular stations. The short axis of lymph node was defined as the lesion size. The final diagnosis was confirmed by pathology and clinical follow-up. Data collection and interpretation included identification of primary malignancy, pathologic types of primary tumors, distribution, size and SUV_max of the metastatic lymph nodes. One-way analysis of variance and linear correlation analysis were used for data analysis. Results: In 78 subjects, 75 were diagnosed as having malignant and 3 as benign lymph nodes by excisional biopsy. ¹⁸F-FDG PET/CT detected primary malignancy in 56 cases (71.8%, 56/78). In these 56 cases, 57.1% (32/56) had head and neck cancer with metastatic lymph nodes mainly distributed in levels Ⅱ, Ⅲ and Ⅳ (90.6%, 29/32). The remaining 24/56 (42.9%) patients had primary malignancy of the trunk with metastatic lymph nodes primarily involving supraclavicular fossa (95.8%, 23/24). There was no statistical difference in size and SUV_max of lymph node among different primary locations or pathological types (F=0.037-2.413, all P>0.05). Conclusion: ¹⁸F-FDG PET/CT may play an important role in the detection of primary cancers for patients with metastatic cervical lymph nodes from unknown origin. (authors)