Asia Oceania Journal of Nuclear Medicine and Biology

Asia Oceania Journal of Nuclear Medicine and Biology

Melanoma metastasizing to the Gall bladder - A case report and literature review

Articles in Press

Document Type : Case report

Authors
Shaghayegh Ranjbar 1
Mehrshad Abbasi 2
Yalda Salehi 1
Fatemeh Saboktakin 1
Niloofar Tabatabaeian 3
1 Tehran University of Medical Sciences, Nuclear medicine
2 Department of Nuclear Medicine, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences
3 Department of Nuclear Medicine, Vali-Asr Hospital, Tehran University of Medical Sciences
10.22038/aojnmb.2026.91013.1670
Abstract
Melanoma demonstrates high metastatic potential, but gallbladder involvement is exceptionally rare and often asymptomatic. We present a 71-year-old male with ulcerated lower lip mucosal melanoma (Breslow 4.2 mm) and pulmonary metastases on baseline 18F-FDG PET/CT. After pembrolizumab therapy, lung lesions regressed, but new gallbladder wall thickening with moderate FDG uptake (SUVmax 5.1) appeared. The patient was asymptomatic with normal liver function tests. Laparoscopic cholecystectomy revealed a 2.2 cm lesion; histopathology confirmed metastatic epithelioid melanoma with lymphovascular invasion. Immunohistochemistry was positive for HMB-45, Melan-A, SOX10, and S-100 (Ki-67: 70%). Literature shows variable SUVmax for gallbladder metastases (6.6–22.5), complicating differentiation from benign conditions such as cholecystitis. This case emphasizes FDG-PET/CT’s role in detecting atypical metastases in melanoma surveillance, while underscoring the need for histopathological confirmation due to variable uptake patterns. Early surgical intervention can prevent complications and guide therapeutic decisions. Clinicians should consider gallbladder metastasis in melanoma patients with new PET/CT scan findings, even in the absence of symptoms.
Keywords
Gallbladder metastasis
Melanoma
FDG-PET
Subjects
Asia Oceania Journal of Nuclear Medicine and Biology

Articles in Press, Accepted Manuscript
Available Online from 28 June 2026