Primary malignant melanoma of the oesophagus: a clinical and pathological study with emphasis on the immunophenotype of the tumours for melanocyte differentiation markers and cancer/testis antigens

Primary malignant melanoma of esophagus: clinicopathologic characterization of 20 cases including molecular genetic profiling of 15 tumors

Primary malignant melanoma of esophagus is very rare, and its clinicopathologic and genetic features have not been extensively investigated. In this study, 20 tumors from 14 male and 6 female patients (40-79 years old) were evaluated. Dysphagia, chest pain, and weight loss were frequent symptoms. Thirteen melanomas, including two with multiple lesions, involved the distal third of esophagus. The median tumor diameter was 6 cm. Epithelioid morphology, moderate atypia, and pigmentation were typical findings. None of the patients had melanoma elsewhere, and all tumors exhibited a junctional peri-epithelial component consistent with a primary lesion. The median mitotic activity was 11 per 10 high-power fields (range, 0-31). Nine patients died of tumor within 4-22 months, however, two showed long-term (96 and 104 months) survival. In 15 cases, tissue for further immunohistochemical and molecular studies were available. BRAF, KIT, and NRAS mutation status was assessed by Sanger sequencing in all 15 tumors. The next-generation sequencing of 50 or 409 genes was performed in five and three cases, respectively. IGF1R expression indicating activation of the IGF axis was seen in 82% (9/11) of tumors. However, no BRAF mutations were identified. In 33% (5/15) of tumors, NRAS mutations were detected. KIT expression was seen in 50% (7/14) of melanomas including single KIT mutant. Two of three tumors evaluated with 409 genes panel revealed multiple driver mutations indicating sub-clonal expansion, whereas a single mutation (TSC1 p.H371Q) was the sole change in the third case. SF3B1 p.K666T and p.R625C mutations were detected in two cases. However, no co-occurrence of SF3B1 and GNAQ or GNA11 mutations, seen in uveal melanoma, was detected. FBXW7 p.R465C and p.R479G mutations, linked to cancer progression, were found in two of eight tumors. In summary, esophageal melanoma mutation profile indicates complexity of molecular mechanisms underlying its pathogenesis.

Clinicopathological characteristics and survival of primary malignant melanoma of the esophagus

Primary malignant melanoma of the esophagus (PMME) has been reported to be a rare and highly malignant disease, and to date a standard treatment strategy has not been established due to limited evidence. The aim of the present study was to investigate the clinicopathological characteristics of this extremely rare disease. A total of 6 out of 2,093 patients with PMME treated in our institution between 1995 and 2016 were retrospectively analyzed and their clinicopathological parameters including treatment course and long-term survival were investigated. The major clinicopathological characteristics of patients were that they were >70 years of age, male sex, dysphagia at first diagnosis, and macroscopic black protruding tumors located in the lower third of the thoracic esophagus. Four of the five patients receiving pretherapeutic endoscopic biopsy were correctly diagnosed with PMME, and two patients received preoperative treatment with ineffective histopathological responses. There were two unresectable cases, one was treated with an immune-checkpoint inhibitor and the other received palliative care. Three of the four patients receiving curative surgery developed hematogenous recurrence within two years of surgery and only one patient with pT1aN0M0 achieved long-term survival. The median overall survival of all six patients was 19.6 (6.4–40.5) months. Patients with stage I disease exhibited significantly more favorable prognoses than those with stage II–IV (P=0.025) and surgically-treated patients had significantly better prognoses than those who did not receive surgery (P=0.018). In conclusion, PMME was associated with highly malignant features and tended to develop hematogenous metastases even after radical resection. Early diagnosis appears to be important to cure this refractory disease.

A Retrospective Study, an Initial Lesion of Primary Malignant Melanoma of the Esophagus Revealed by Endoscopy

A 66-year-old man presented to his previous physician with epigastric discomfort in 2014. He was then referred to our hospital due to suspected primary malignant melanoma of the esophagus (PMME). A biopsy showed atypical cells containing melanin granules. A diagnosis of PMME was thus made. We investigated the endoscopic findings of the previous physician, which revealed a black point-like pigmentation at the same site since 2009. In 2010, black pigmentation was also observed at the same site. Although esophageal melanosis was suspected, no biopsy was performed. This case demonstrates the process by which esophageal melanomas develop into malignant melanomas.

Primary malignant melanoma of the esophagus treated by endoscopic submucosal dissection: A case report

Primary malignant melanoma of the esophagus (PMME) is a rare malignant neoplasm of the esophagus. In the majority of cases, the disease originates in the mucosal layer of the esophagus, which is similar to other types of esophageal cancer. With the development of endoscopic submucosal dissection (ESD), endoscopic resection is possible for cases in which melanomas are limited to the mucosal and submucosal layer. However, few studies report the efficiency of ESD for PMME, and no studies perform long-term follow-up. The present study reported the case of a 71-year-old PMME patient who was successfully treated by ESD at The Third Affiliated Hospital of Soochow University (Changzhou, China) in Otober 2011, with a follow-up of >3 years conducted.

Current status of primary malignant melanoma of the esophagus: clinical features, pathology, management and prognosis

Primary malignant melanoma of the esophagus (PMME) is a rare disease with an extremely poor prognosis. Up to 2011, approximately 300 cases had been reported worldwide. The average age of onset is 60.5 years old, with a prevalence of males (2:1). A typical finding of PMME is a lobular or polyploid, well-circumscribed and pigmented tumor, partly covered with normal mucosa. PMME represents various colors depending on its melanin quantity and commonly coexists with intramural metastases, melanocytosis or melanoma in situ. The tumor is located from the middle to lower thoracic esophagus. The accuracy of diagnosis from biopsy is approximately 80%, because many cases are misdiagnosed as a poorly differentiated carcinoma because of the absence of melanin granules. A definite diagnosis was made by immunohistochemical examination with positive results of S100 protein, HMB45 and neuron-specific enolase. PMME has a highly metastatic potential, and the incidence of distant metastasis at the initial diagnosis is around 40-80%. A metastatic tumor from cutaneous malignant melanoma is another pigmented esophageal tumor to be considered when making the differential diagnosis for PMME. Junctional activity with melanotic cells in the adjacent epithelium and the presence of in situ melanoma and/or a satellite tumor without a previous history of cutaneous melanoma are definitive. Most of the reported patients were treated with radical esophagectomy, which is believed to be an effective approach for localized PMME. Five-year survival rates have been achieved in 37% recently, while adjuvant therapy has not been proven to increase overall survival but plays a palliative role.

Amelanotic malignant melanoma of the esophagus: Report of two cases with immunohistochemical and molecular genetic study of KIT and PDGFRA

The author reports herein two cases of amelanotic malignant melanoma of the esophagus. Case 1 is an 87-year-old woman who was admitted to our hospital because of nausea and vomiting. Endoscopic examination revealed an ulcerated tumor of the distal esophagus, and a biopsy was taken. The biopsy showed malignant polygonal and spindle cells. No melanin pigment was recognized. Immunohistochemically, the tumor cells were positive for melanosome (HMB45), S100 protein, KIT and Platelet derived growth factor receptor-α (PDGFRA). The patient was treated by chemotherapy and radiation, but died of systemic metastasis 12 mo after the presentation. Case 2 is a 56-year-old man presenting with dysphagia. Endoscopic examination revealed a polypoid tumor in the middle esophagus, and a biopsy was obtained. The biopsy showed malignant spindle cells without melanin pigment. Immunohistochemically, the tumor cells were positively labeled for melanosome, S100 protein, KIT and PDGFRA. The patient refused operation, and was treated by palliative chemotherapy and radiation. He died of metastasis 7 mo after the admission. In both cases, molecular genetic analyses of KIT gene (exons 9, 11, 13 and 17) and PDGFRA gene (exons 12 and 18) were performed by the PCR direct sequencing method, which showed no mutations of KIT and PDGFRA genes. This is the first report of esophageal malignant melanoma with an examination of the expression of KIT and PDGFRA and the mutational status of KIT and PDGFRA genes.

Esophageal melanomas harbor frequent NRAS mutations unlike melanomas of other mucosal sites

Mucosal melanomas have genetic alterations distinct from those in cutaneous melanomas. For example, NRAS- and BRAF-activating mutations occur frequently in cutaneous melanomas, but not in mucosal melanomas. We examined 16 esophageal melanomas for genetic alterations in NRAS, BRAF, and KIT to determine whether they exhibit genetic features common to melanomas arising from other mucosal sites. A sequencing analysis identified NRAS mutations in six cases; notably, four of these mutations were located in exon 1, an uncommon mutation site in cutaneous and other mucosal melanomas. BRAF and KIT mutations were found in one case each. Immunohistochemistry showed KIT expression in four cases, including the tumor with a KIT mutation and two other intramucosal tumors. The low frequency of BRAF mutations and the presence of a KIT mutation-positive case are findings similar to those of mucosal melanomas of other sites, but the prevalence of NRAS mutations was even higher than that of cutaneous melanomas. The present study implies that esophageal melanomas have genetic alterations unique from those observed in other mucosal melanomas.