Metastases of malignant melanoma to stomach

Malignant melanoma (MM) is one of the most common tumours that metastasises to the gastrointestinal (GI) tract. The small intestines are the most common site for this metastasis; however, the stomach is also a rare site [1, 2].
A 58-year-old male patient applied to the gastroenterology outpatient clinic with nausea and epigastric pain. He had a history of localised cutaneous MM excision from the right thigh 5 years earlier. Lab work showed no significant abnormality on blood biochemistry. His esophagogastroduodenoscopy showed multiple, black-pigmented lesions of various sizes (Figure 1). A biopsy from these lesions revealed MM metastasis (Figure 2).
Malignant melanoma may involve the GI tract as a metastatic lesion, or rarely as a primary tumour. Gastrointestinal tract metastasis can be seen synchronous with the primary tumour, or as a recurrent tumour years later [1, 2]. Gastric involvement may be seen as a black-pigmented ulcer or as diffusely spread black-pigmented lesions, as in our case [3]. However, a histopathological exam may not differentiate a primary lesion from a metastatic one [4]. Immunohistochemistry should be employed to prove MM with markers such as HMB-45 and S100 [5]. Treatment options for metastatic involvement of the GI tract with MM are surgery, chemotherapy, immunotherapy, and palliative therapy. Only surgery is reported to increase survival to some extent [1].
As a result, because MM metastasis may show up years later, we suggest screening of GI tract in MM patients if there is the presence of GI symptoms.

Conflict of interest

The authors declare no conflict of interest.

References

1. Schuchter LM, Green R, Fraker D. Primary and metastatic diseases in malignant melanoma of the gastrointestinal tract. Curr Opin Oncol 2000; 12: 181-5.
2. Liang KV, Sanderson SO, Nowakowski GS, Arora AS. Metastatic malignant melanoma of the gastrointestinal tract. Mayo Clin Proc 2006; 81: 511-6.
3. Katsanos KH, Tsianos VE, Tsianos EV. Metastatic melanoma in stomach and large bowel. Ann Gastroenterol 2010; 23: 322-4.
4. Kotteas EA, Adamopoulos A, Drogitis PD, et al. Gastrointestinal bleeding as initial presentation of melanoma of unknown primary origin: report of a case and review of the literature. In Vivo 2009; 23: 487-9.
5. Clemmensen OJ, Fenger C. Melanocytes in the anal canal epithelium. Histopathology 1991; 18: 237-41.

Received: 8.04.2015
Accepted: 18.05.2015