PET-CT in noncutaneous melanoma

1353 Learning Objectives To demonstrate the utility of FDG PET-CT in the staging and restaging of ocular and mucosal melanoma. Noncutaneous melanomas are relatively rare, with ocular melanomas accounting for 5.5% and mucosal melanomas accounting for 1.3% of all melanomas.(1) Noncutaneous melanomas can be divided into ocular (uveal, choroidal), mucosal (head & neck,GI and genitourinary tracts) and unknown primary. The incidence ranges from 0.2-10%, depending on the population (2). Noncutaneous melanomas demonstrate differences in tumor biology. Mucosal melanoma occurs in an older population (average age of 67 vs 55 yrs for cutaneous). Furthermore, patients with noncutaneous melanoma often present with advanced disease (>50%) and have an overall poorer prognosis (3). The management of noncutaneous melanoma also differs from cutaneous with adjuvant radiotherapy post primary resection recommended. The role of chemotherapy and immunotherapy is not as well established (3) and there are no well established guidelines for staging. FDG PET-CT has been evaluated predominantly for cutaneous melanomas and has been shown to detect more visceral and nonvisceral metastases than PET or CT alone (4). Meta-analyses show better sensitivity and specificity of PET-CT in stage III/IV cutaneous melanoma than standard imaging, leading to change in management in 15-64% of patients. An overall accuracy of up to 97.2% (vs CT 78.8%) has been reported (5). Despite the evidence regarding the utility of PET-CT in cutaneous melanoma, data supporting its use in noncutaneous melanomas is scarce. A case series of 52 patients with choroidal melanoma revealed that PET identified most T2 and T3 tumors and showed unsuspected disease in 4 patients, including metastases and synchronous primaries (6). There are few other studies involving noncutaneous melanoma- predominantly case reports and series. In this pictorial review, we will demonstrate the impact of PET-CT in primary staging, restaging and as a clinical problem solving tool in this uncommon tumor.