Malignant melanoma is an extremely malignant tumor with an unpredictable profile of spread and variable periods of remission. The late recurrence of malignant melanoma after diagnosis and treatment is a rare but characteristic metastatic behavior of malignant melanoma. When the late recurrence of malignant melanoma occurs, the most common sites of metastasis are the skin, subcutaneous tissue and lymph nodes.Case
A 41-year-old woman presented with recurrent malignant melanoma which had clinical features of an acute state mimicking peritoneal cancer. Seven years after the excision of the primary tumor, the patient noticed diffuse abdominal distention. The patient underwent computed tomography and magnetic resonance imaging examination, which demonstrated extensive nodularity of the peritoneal surfaces, soft tissue thickening of the omentum and large amount of ascites. Therefore, primary peritoneal cancer was initially considered the most likely diagnosis. The patient underwent an exploratory laparotomy. Macroscopically, a numerous number of white-yellow rubbery nodules of tumor were present diffusely in the ovaries and omentum and on the uterine serosal surface. The pathological examination showed poorly differentiated adenocarcinoma of peritoneum. The tumor cells showed strong positivity by immunohistochemistry for S-100, melan A and vimentin. The diagnosis was established post-operatively by immunohistochemistry. Our case was an unusual recurrent case of malignant melanoma occurring 7 years after diagnosis and treatment of malignant melanoma.Conclusion
The incidence of malignant melanoma has been increasing. The late recurrence of malignant melanoma may be seen frequently in the future. A variety of imaging and pathological methods including an exploratory laparotomy may be necessary in cases of patients suspecting peritoneal cancer with a previous history of melanoma.