Clinicopathological findings of primary esophageal malignant melanoma: report of six cases and review of literature

Abstract

We studied images and histopathological features of primary esophageal malignant melanoma to explore the clinical pathological features, diagnosis, differential diagnoses, and treatment. Immunolabelling was conducted on six cases of esophageal malignant melanoma using histological and immunohistochemical techniques. Combined with the related literature, the clinical manifestations, imaging, histopathological and immunohistochemical features, treatment, and prognosis of primary esophageal malignant melanoma were observed and analyzed. The six patients with primary esophageal malignant melanoma were all male with an average age of 63.4 years. Poor food intake was observed in all patients, and the symptoms showed progressive aggravation. Endoscopic feed tube revealed dark brown and black nodular and polypoid lesions, 1/4-1/2 loop cavity. Tumor histopathology revealed the following characteristics: tumor cells arranged in nests, sheets and cords, round or polygonal, abundant and red-stained cytoplasm, melanin granules in the cytoplasm, heterogeneous nucleus sizes, centered or deviated nuclei, clearly identifiable nucleoli, and apparent pathological mitosis. The immune phenotype was as follows: tumor cells had diffuse expression of HMB45, Melan A, and S100. The cells were CK negative, and the Ki67-positive cell number was 40%-45%. Primary esophageal malignant melanoma is rare with high malignancy and poor prognosis. Immunohistochemical staining is helpful for diagnosing this tumor. The differential diagnosis includes low differentiated carcinoma, primitive neuroectodermal tumor, esophageal sarcomatoid carcinoma, esophageal lymphoma, and other tumors.

Keywords: Esophagus; differential diagnosis; immunohistochemistry; malignant melanoma; tumor.

Figure 1

A. Endoscopic characteristics of esophageal malignant melanoma. B. Ultrasonic endoscope of the feed tube wall shows 1/4-1/2 loop cavity, dark brown and black nodular and polypoid lesions. C. Positron emission tomography-computed tomography (PET-CT) features of esophageal malignant melanoma.

Figure 2

Gross characteristics of malignant melanoma in the locus medialis.

Figure 3

A. Histopathological features of esophageal malignant melanoma. B. Malignant melanoma immunohistochemistry staining of positive HMB45 in the locus medialis. C. Malignant melanoma staining positive for Melan A in the locus medialis. D. Malignant melanoma staining positive for S-100 in the locus medialis. E. Malignant melanoma negative for CK in the locus medialis. F. Positive Ki67 cells (40%-50%) of malignant melanoma staining in the locus medialis.