Scanning with 18F-FDG-PET/CT for Detection of Pelvic Nodal Involvement in Inguinal Node-Positive Penile Carcinoma

Background

Penile carcinoma patients with inguinal lymph node involvement (LNI) have an increased risk for pelvic nodal involvement with or without distant metastases.

Objective

To evaluate the diagnostic accuracy of fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) with computed tomography (CT; 18F-FDG PET/CT) scanning in determining further metastatic spread in patients with tumour-positive inguinal nodes.

Design, setting, and participants

Eighteen patients with penile squamous cell carcinoma with unilateral or bilateral cytologically tumour-positive inguinal disease underwent whole-body 18F-FDG-PET/CT scanning for tumour staging.

Measurements

Images were blindly assessed by two nuclear medicine physicians. All scans were evaluated for pelvic nodal involvement per basin and for distant metastases. Histopathology (when available), radiologic imaging, and clinical follow-up (with a minimum of 1 yr) served as a reference standard. The diagnostic value of PET/CT scanning for predicting pelvic nodal involvement was evaluated using standard statistical methods.

Results and limitations

The reference was available in 28 of the 36 pelvic basins. Of the 11 tumour-positive pelvic basins, 10 were correctly predicted by PET/CT scan, as were all 17 tumour-negative pelvic basins. PET/CT scan showed a sensitivity of 91%, a specificity of 100%, a diagnostic accuracy of 96%, a positive predictive value of 100%, and a negative predictive value of 94% in detecting pelvic nodal involvement. Additionally, PET/CT scans showed distant metastases in five patients. In four patients, the presence of distant metastases could be confirmed, while in one patient, no radiologic confirmation was found for that particular lesion. A potential limitation is that the diagnostic accuracy of PET/CT scanning was calculated on 28 pelvic basins only. Furthermore, no comparison was made with conventional CT scans, as not all patients had undergone contrast-enhanced CT scans.

Conclusions

PET/CT scanning appears promising for detecting pelvic lymph node metastases with great accuracy, and it identifies distant metastases in penile carcinoma patients with inguinal LNI. In our practice, PET/CT scanning has become part of routine staging in such patients.