Flat-type primary malignant melanoma of the esophagus

Case report

A 63-year-old woman was referred to our hospital for further investigation of a gastric mucosal abnormality in an upper gastrointestinal series. Esophagogastroduodenoscopy (EGD) demonstrated two areas of flat, widespread blackish pigmentation situated 30 to 33 cm, and 34 to 38 cm from the incisor teeth ([Fig. 1]), and no gastric mucosal abnormality. Distinguishing malignant melanoma from diffuse melanocytosis is difficult due the absence of polypoid morphology. Several parts of these flat lesions were biopsied at random. However, biopsies could not be diagnosed as a malignant melanoma in situ because of the loss of neoplastic proliferation ([Fig. 2]). Computed tomography demonstrated no abnormal lesion in the esophagus and no enlarged regional lymph nodes. Positron emission tomography-computed tomography (PET-CT) showed no metastases, and a skin survey revealed no cutaneous melanoma. Follow-up examination or surgical resection with a three-stage esophagectomy were discussed; however, the patient wished to proceed with a definite diagnosis of these lesions. The patient underwent endoscopic submucosal dissection (ESD) of two areas that showed strong blackish pigmentation to obtain a definite diagnosis. The resection specimens contained two tumors, 28 × 11 mm and 23 × 15 mm in size ([Fig. 3]). Histopathologically, the tumor was localized to the mucosa with partial subepithelial invasion ([Fig. 4 a, b]), and was diagnosed as a primary malignant melanoma of the esophagus (PMME) according to immunohistological results (positive for HMB-45 [[Fig. 4 c]] and Melan A [[Fig. 4 d]]). The patient underwent additional surgical resection with a three-stage esophagectomy for radical treatment. TNM7 classification was T1aN0M0, stage IA. At 10 months after surgery, the patient showed no recurrence.

Fig. 1 Endoscopic image of the mid and lower esophagus. a, b white-light endoscopy showing a flat, widespread blackish pigmentation without polypoid morphology situated 30 to 33 cm (a, lesion 1) and 34 to 38 cm (b, lesion 2) from the incisor teeth.

Fig. 2 Biopsy specimen showing melanocytes localized to the mucosa along the basal membrane without junctional activity and neoplastic proliferation (a, hematoxylin and eosin (HE) staining, middle-power view; b, HE staining, high-power view). These findings presented difficulty in distinguishing between malignant melanoma and melanocytosis.

Fig. 3 Resection specimens by endoscopic submucosal dissection (ESD) showing a flat, widespread blackish pigmentation without polypoid morphology. a Lesion 1: Lt, 23 × 15 mm or more, 0-IIb, malignant melanoma, pt1a/EP, ly0, v0, pHM1, pVM0. b Lesion 2: Lt, 28 × 11 mm or more, 0-IIb, malignant melanoma, pt1a/LPM, INFa, ly0, v0, pHM1, pVM1.

Fig. 4 a, b Endoscopic submucosal dissection (ESD) specimen (lesion 2) showing atypical melanocytes containing pigment localized to the mucosa along basal membrane with subepithelial invasion (hematoxylin and eosin (HE) staining). c, d Tumor cells were positive for HMB-45 (c) and Melan A (d). Definite diagnosis of malignant melanoma was confirmed by the subepithelial invasion and positivity for HMB-45 and Melan A.

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