[Primary Malignant Melanoma of the Gallbladder]

Area of Science:

• Oncology
• Gastroenterology

Background:

• Primary malignant melanoma of the gallbladder is an exceptionally rare condition, with fewer than 40 cases documented in medical literature.
• Malignant melanoma typically arises from melanocytes in the skin or eyes, making extrermal presentations uncommon.

Observation:

• A 78-year-old male presented with a pelvic tumor causing left leg edema due to external iliac vein compression.
• Post-resection, the pelvic tumor was pathologically diagnosed as malignant melanoma.
• The patient subsequently developed anorexia and upper right abdominal discomfort, with FDG-PET scans revealing significant uptake in the gallbladder and lower abdominal lymph nodes.

Findings:

• Surgical resection of the gallbladder confirmed primary malignant melanoma, with junctional activity observed in the gallbladder wall.
• Absence of cutaneous or ocular melanocytic lesions supported the diagnosis of gallbladder as the primary site.
• Despite chemotherapy, the patient's condition progressed, leading to mortality.

Implications:

• This case underscores the diagnostic challenge posed by rare extrermal melanomas.
• It emphasizes the necessity of comprehensive histopathological and imaging evaluations for accurate diagnosis.
• The findings contribute to the limited understanding of gallbladder melanoma, potentially informing future diagnostic and treatment strategies.