To the Editor:
Metastatic melanoma of the gallbladder is extremely rare, and despite appropriate therapy its prognosis is poor with few patients surviving more than 2 years. We present a case of gallbladder involvement by malignant melanoma in a 63-year-old man initially diagnosed with gallbladder cancer. The man with a history of malignant melanoma resected from his back 18 years ago was admitted to our hospital because of severe right upper abdominal pain two days before admission.
Ultrasonography and magnetic resonance showed an 8 cm mass in the gallbladder lumen (Fig. 1). Chest X-ray, tumoral markers (CEA and CA19-9), and blood analyses showed nothing abnormal. Gallbladder cancer was suspected for immediate surgical treatment. A cholecystectomy with resection of liver segments Ⅳb and Ⅴ and a lymphadenectomy of the hepatic hilus were performed for the gallbladder cancer. The mass inside the gallbladder lumen measured 8 cm and had a single attachment point to the mucosal surface, darkly colored (Fig. 2). Histological evaluation showed a malignant melanoma with no signs of lamina propria or muscularis invasion. None of the 12 dissected lymph nodes showed signs of metastasis. The postoperative course was uneventful and the patient was discharged on postoperative day 5.
Melanoma can metastasize to any organ, and gastrointestinal metastases occur in 2%-4% of the patients.[1] Isolated metastasis to the gallbladder is rare and most patients have widespread disease by the time of diagnosis.[2] Over 50% of metastatic gallbladder lesions are from melanomas and this can be explained by the hematogenous spread of melanoma to the abdomen.[3]
Most patients with melanoma metastatic to the gallbladder are asymptomatic, and the most common symptom is acute cholecystitis due to cystic duct obstruction.[3] Right upper quadrant or epigastric pain, weight loss, nausea, and vomiting may be present.[3] Radiographic examination is useful to determine gall-bladder masses. Ultrasonography is the most useful tool for assessing gallbladder lesions and can reveal an intracholecystic nodule or mass. CT scan has an important role in the detection of metastatic disease.
In the present case, the mass inside the gallbladder was misdiagnosed as a gallbladder cancer, and was treated according to this hypothesis.
Since gallbladder melanoma is a rare entity, there is no optimal therapy for this kind of tumor. Its prognosis is very poor, with a survival period of 8.54 months for metastatic lesions.[4] Apparently, aggressive surgical therapy tends to prolong the survival rate, and to improve the quality of life of patients.[2] The treatment is dependent on the extension of the disease and the status of the patient. In the present case the tumor was limited to the gallbladder, and surgery, misindicated for a gallbladder cancer, aimed to prevent symptoms or tumor complications and to improve the prognosis. The patient remained well without symptoms, and 2 years latter showed a metastasis to the tonsil that was resected. Ten months later, the patient presented 2 pulmonary metastases and was referred to reavaliation by the clinical oncologist.
The role of adjuvant chemotherapy and immuno-therapy is still controversial for metastatic gastrointestinal melanoma.[1] In patients with a gallbladder mass and a history of cutaneous melanoma, isolated metastatic melanoma has to be diagnosed despite its rarity. In spite of its poor prognosis, a surgical approach seems to be the best treatment.