Primary gastric melanoma presenting as a nonhealing ulcer

Primary malignant melanoma of the stomach: report of a case

“…A definitive diagnosis of MM was made by immunohistological examination of harvested tissues. Since melanocytes are very sensitive to S-100 proteins and HMB-45 antibodies, immunohistochemical staining with those pigments is important to confirm the presence of melanocytes in a tumor [5, 7, 20]. Immunohistochemical examination of the tumor from our patient revealed a positive reaction with S-100 proteins and HMB-45 antibodies, which led us to assume a primary MM of the stomach.…”

“…For example, ectopic migration of melanocyte precursors or differentiation of the APUD cells (amine precursor uptake and decarboxylation cells) to melanocytes has been suggested as a possible mechanism of the development of MM [8, 15, 16]. Criteria for the diagnosis of primary MM include the absence of other primary site melanomas and no history of the removal of a melanoma or atypical melanocytic lesion from the skin or other organs [5, 17]. It is recognized that spontaneous regression of primary melanoma occasionally occurs [5, 7, 18, 19].…”

“…Criteria for the diagnosis of primary MM include the absence of other primary site melanomas and no history of the removal of a melanoma or atypical melanocytic lesion from the skin or other organs [5, 17]. It is recognized that spontaneous regression of primary melanoma occasionally occurs [5, 7, 18, 19]. Moreover, metastatic melanoma of the GI tract is found in up to 60% of autopsies of patients who have died with primary cutaneous melanoma [3, 4].…”

“…MMs that arise in mucosal surfaces appear to be more aggressive and associated with a worser prognosis than cutaneous MMs. This poorer prognosis may be related to late diagnosis, an inherently more aggressive behavior of mucosal MM, or earlier dissemination because of the rich lymphatic and vascular supply of GI tract mucosa [5, 7, 8, 10]. It has been reported that the median overall survival associated with primary MM of the GI tract is 17 months, whereas that associated with primary MM of the stomach is only 5 months [21].…”

“…In fact, clinical GI tract involvement secondary to cutaneous melanoma has been reported in up to 4% of living patients and up to 60% at autopsy [3, 4]. Conversely, primary MM of the GI tract, particularly in the stomach, is extremely rare, although sporadic cases have been reported [5–14]. We present another case of primary MM of the stomach, which to our knowledge, is the first documented case of a primary MM of the stomach, from Japan.…”