Purpose
Uveal melanoma metastasizes preferentially to liver that manifests several years after treatment of the primary tumor. Although, there is lack of consensus regarding surveillance protocols, periodic liver imaging studies is increasingly utilized. We analyzed the effectiveness of hepatic ultrasonography in the diagnosis of asymptomatic hepatic metastases in patients with uveal melanoma.
Methods
We conducted a retrospective chart review of patients diagnosed and treated for uveal melanoma at the Cole Eye Institute from the year 2003 to 2011. Inclusion criteria included patients with a diagnosis of primary uveal melanoma that were assessed using a standardized protocol; initial staging with contrast enhanced CT scan of the chest, abdomen and pelvis immediately prior to the treatment of the primary and subsequent surveillance with hepatic function panel and liver ultrasound (USG) every six months. Abnormal USG findings that were not present on baseline CT were categorized as cyst and hemangioma, indeterminate lesion, suspicious for metastases, and consistent with metastases. Lesions that were indeterminate, suspicious or consistent for metastases were further evaluated by a CT/MRI or PET scan and the diagnosis of metastatic lesion was confirmed with a tissue biopsy. The rest were serially imaged by USG.
Results
A total of 265 patients were included in the study. 2 patients (0.8%) were found to have metastases at initial staging. The liver USG scan data (1390 scans) was analyzed for 263 patients. The number of scans per patient ranged from 1 to 17 (mean: 5.3), performed over a median period of 34 months (range: 0.2-125). Overall 86 scans of 71 patients [27%] were reported as abnormal (Table 1). 36 (13.6%) had biopsy confirmed hepatic metastases (Table 2). None of the patients with indeterminate lesions developed metastases where as only one patient initially diagnosed with a cyst was later found to have metastasis. 30 of the 45 patients with suspicious lesions (66.7%) and 100% of patients with consistent lesions proved to have a positive biopsy (positive predictive value of 53%).
Conclusions
Periodic ultrasonography of the liver performed as part of systemic surveillance protocol is able to identify asymptomatic metastatic lesions. However, because of its low positive predictive value other imaging techniques need to be evaluated.