ELECTRONIC IMAGE OF THE MONTH Primary Gastrointestinal Malignant Melanoma Kazuhiro Imamura,*,a Kensuke Adachi,*,a and Kazuaki Enatsu‡ *Department of Surgery, ‡Department of Pathology, Tokyo Metropolitan Tama Medical Center, Tokyo, Japan
previously healthy, 51-year-old woman was referred to our hospital because of a gastric tumor adjoining the esophagogastric junction (EGJ). This tumor was discovered incidentally by an upper gastrointestinal (GI) series in the course of her annual medical check-up. The patient’s history was unremarkable. Physical examination and laboratory work-up showed no abnormalities. An esophagogastroduodenoscopy showed a dark-red EGJ tumor and a black blot accompanied by gray pigmentation scattered over almost the entire esophagus (Figure A and B). An endoscopic biopsy of the lesions showed proliferation of atypical melanocytes, which were immunohistochemically positive for the melanoma-specific antigen HMB-45 (Figure C). Further investigation showed no evidence for other manifestations of the malignant melanoma or metastasis from an
A
extra-GI melanoma into these lesions. Preoperative computed tomography found no local or systemic metastases. The patient underwent a radical surgical resection with gastric tube pull-up. She received no adjuvant therapy although postoperative pathology showed lymph node metastasis in the upper mediastinum. She has been free of recurrence now for 1 year. Microscopically, the EGJ tumor presented some features of a skip lesion because it spread in the direction of the proximal esophageal epithelium and distal gastric mucosa (Figure D, red lines, skip lesions; yellow arrowhead, EGJ). This intraepithelial extension consisting of melanoma cells and atypical melanocytes is called radial growth (Figure E, green arrows), which is a definitive characteristic of primary mucosal melanoma (PMM).1 Although the exact tumorigenesis was unclear, these
Clinical Gastroenterology and Hepatology 2015;-:-–-
ELECTRONIC IMAGE OF THE MONTH, continued findings suggested that the tumor might have originated in the distal end of the esophagus. Subsequently, it might have acquired bidirectional development as an expansile growth in the stomach, and as a longitudinal intramural extension into the esophagus. Consequently, the former harbored melanoma cells in the muscularis propria, the latter in the lamina propria. PMMs presumably arise from malignant degeneration of precedent melanocytes in the epithelium-stromal junction; therefore, melanocytosis is considered a precursor to the development of PMMs. Despite their paucity, they sometimes involve the GI tract, including the esophagus and anorectum, where melanocytes usually exist.2 Primary gastrointestinal malignant melanomas are known as a devastating malignancy with a dismal prognosis. This may reflect their identification at a more advanced stage. However, early diagnosis of this disease entity poses a formidable dilemma unless the black pigmentation is recognized endoscopically. Furthermore, they occasionally conceal themselves behind a light-gray, brown, tan, blue, or dark-red discoloration, depending on the melanin quantity.
e2
These situations also cause endoscopic biopsy specimens to be mistaken for poorly differentiated carcinoma, especially when the melanoma cells contain few or no melanin granules (eg, amelanotic melanoma). Because chemoradiotherapy reportedly is ineffective, early detection followed by radical surgical resection forms the mainstay of treatment.2
References 1.
Raven RW, Dawson I. Malignant melanoma of the esophagus. Br J Surg 1964;51:551–555.
2.
Bisceglia M, Perri F, Tucci A, et al. Primary malignant melanoma of the esophagus: a clinicopathologic study of a case with comprehensive literature review. Adv Anat Pathol 2011; 18:235–252.
a
Authors share co-first authorship.
Conflicts of interest The authors disclose no conflicts. © 2015 by the AGA Institute 1542-3565/$36.00 http://dx.doi.org/10.1016/j.cgh.2015.05.015
previously healthy, 51-year-old woman was referred to our hospital because of a gastric tumor adjoining the esophagogastric junction (EGJ). This tumor was discovered incidentally by an upper gastrointestinal (GI) series in the course of her annual medical check-up. The patient’s history was unremarkable. Physical examination and laboratory work-up showed no abnormalities. An esophagogastroduodenoscopy showed a dark-red EGJ tumor and a black blot accompanied by gray pigmentation scattered over almost the entire esophagus (Figure A and B). An endoscopic biopsy of the lesions showed proliferation of atypical melanocytes, which were immunohistochemically positive for the melanoma-specific antigen HMB-45 (Figure C). Further investigation showed no evidence for other manifestations of the malignant melanoma or metastasis from an
A
extra-GI melanoma into these lesions. Preoperative computed tomography found no local or systemic metastases. The patient underwent a radical surgical resection with gastric tube pull-up. She received no adjuvant therapy although postoperative pathology showed lymph node metastasis in the upper mediastinum. She has been free of recurrence now for 1 year. Microscopically, the EGJ tumor presented some features of a skip lesion because it spread in the direction of the proximal esophageal epithelium and distal gastric mucosa (Figure D, red lines, skip lesions; yellow arrowhead, EGJ). This intraepithelial extension consisting of melanoma cells and atypical melanocytes is called radial growth (Figure E, green arrows), which is a definitive characteristic of primary mucosal melanoma (PMM).1 Although the exact tumorigenesis was unclear, these
Clinical Gastroenterology and Hepatology 2015;-:-–-
ELECTRONIC IMAGE OF THE MONTH, continued findings suggested that the tumor might have originated in the distal end of the esophagus. Subsequently, it might have acquired bidirectional development as an expansile growth in the stomach, and as a longitudinal intramural extension into the esophagus. Consequently, the former harbored melanoma cells in the muscularis propria, the latter in the lamina propria. PMMs presumably arise from malignant degeneration of precedent melanocytes in the epithelium-stromal junction; therefore, melanocytosis is considered a precursor to the development of PMMs. Despite their paucity, they sometimes involve the GI tract, including the esophagus and anorectum, where melanocytes usually exist.2 Primary gastrointestinal malignant melanomas are known as a devastating malignancy with a dismal prognosis. This may reflect their identification at a more advanced stage. However, early diagnosis of this disease entity poses a formidable dilemma unless the black pigmentation is recognized endoscopically. Furthermore, they occasionally conceal themselves behind a light-gray, brown, tan, blue, or dark-red discoloration, depending on the melanin quantity.
e2
These situations also cause endoscopic biopsy specimens to be mistaken for poorly differentiated carcinoma, especially when the melanoma cells contain few or no melanin granules (eg, amelanotic melanoma). Because chemoradiotherapy reportedly is ineffective, early detection followed by radical surgical resection forms the mainstay of treatment.2
References 1.
Raven RW, Dawson I. Malignant melanoma of the esophagus. Br J Surg 1964;51:551–555.
2.
Bisceglia M, Perri F, Tucci A, et al. Primary malignant melanoma of the esophagus: a clinicopathologic study of a case with comprehensive literature review. Adv Anat Pathol 2011; 18:235–252.
a
Authors share co-first authorship.
Conflicts of interest The authors disclose no conflicts. © 2015 by the AGA Institute 1542-3565/$36.00 http://dx.doi.org/10.1016/j.cgh.2015.05.015
