The role of F-18 FDG PET/CT in patients with malignancy initially presenting as cervical lymphadenopathy

Objectives The purpose of this study was to assess the role of PET/CT in patients with malignancy initially presenting as cervical lymphadenopathy.

Methods Thirty three patients with biopsy proven cervical metastatic LNs (lymph nodes) and unknown primary tumor were enrolled (24 male, 7 female; age 63±15.6). PET/CT was performed between November 2003 and June 2011. Those lost to follow up were excluded. Tumor histology, detection rate of primary tumor, distribution of primary tumor site and cervical LN level, SUVmax of primary site and cervical LNs, additional distant metastases were investigated.

Results Primary tumors were detected by PET/CT in 19 patients, two of them confirmed to be false positive. The primary tumor remained undetermined in 14 patients after conventional investigations and PET/CT. PET/CT detection rate of the primary tumor was 48%(16/33). The most commonly involved locations were the head and neck (9, 27%), followed by the stomach (3, 9%) and lung (2, 6%). Lymphadenopathies at or above level II were most often associated with tonsil cancer. When found below level II, however, thorax and abdominal cancer was more prevalence. Squamous cell carcinoma (15, 45.4%) was the predominant histology of the cervical LNs, followed by poorly differentiated carcinoma (9, 27.2%). In 2 patients, primary site of tumor was undetected by conventional imaging modalities and revealed only by PET/CT. And in 8 patients, PET/CT accurately demonstrated further metastatic spread. SUVmax of the detected primary tumors ranged from 4.5 to 20.7 while that of cervical lymphadenopathies ranged from 1.9 to 32.3.

Conclusions PET/CT detected about 50% of the primary site and additional metastases of malignancy initially presenting as cervical lymphadenopathy. Two were diagnosed by PET/CT alone. So as a diagnostic tool, PET/CT can contribute to appropriate therapeutic plans for such patients