Comparison of primary and metastatic malignant melanoma of the esophagus: Clinicopathologic review of 10 cases

Context. - Primary esophageal melanoma (PEM) is a rare disease and is difficult to distinguish from other esophageal malignancies and from metastatic melanoma. Objective. - To develop diagnostic criteria for PEM, we compared the clinicopathologic features of 5 PEMs and 5 metastatic melanomas to esophagus. Design. - Ten cases of esophageal melanoma, including 4 surgically resected specimens, 2 autopsy cases, and 4 cases reported on mucosal biopsies, were reviewed. The histologic parameters used in this study were well-characterized features for cutaneous melanoma, including junctional component (in situ melanoma), radial growth phase, modified Breslow thickness, depth of invasion, lymphovascular invasion, satellitosis, predominant type of cytology, and regional lymph node metastasis. Clinical and follow-up information was obtained by reviewing patients' medical records. Results. - Previous history of cutaneous melanoma was present in all 5 cases of metastatic esophageal melanoma but was not present in the 5 patients with PEMs. In situ melanoma and/or radial growth phase were identified in all 5 PEMs but were not present in any of the metastatic cases. Among the 4 resected and 2 autopsy cases, melanocytosis and mixed epithelioid and spindle cell morphology was present in 2 (50%) of 4 PEMs but was not present in 2 (40%) of the metastatic melanomas. Melanin pigment was detectable in all cases. Patients with PEM had better survival than those who had metastatic melanoma to esophagus (P = .03). Conclusions. - The presence of in situ melanoma, radial growth phase, melanocytosis, and mixed epithelioid and spindle cell morphology, in the context of no history of melanoma, distinguishes PEM from metastatic melanoma.