Atypical melanocytic proliferation associated with squamous cell carcinoma in situ of the esophagus

We present the case of a 64-year-old woman who underwent a transhiatal esophagectomy subsequent to the presence of high-grade dysplasia of the esophageal squamous epithelium in repeated biopsies. In the resection specimen chronic esophagitis and multifocal carcinoma in situ of the squamous epithelium were diagnosed, associated with a diffuse intraepithelial proliferation of melanocytic cells. While melanocytic hyperplasia (melanocytosis) has previously been recognized as an occasional reactive lesion that can accompany esophageal inflammation and invasive squamous carcinoma, the present case was unusual because of its cytonuclear and architectural atypia in the melanocytic cell population, resembling features of a melanoma in situ in the absence of manifest invasive malignant melanoma. The disappearance of the melanocytic lesion during follow-up supports its nonneoplastic nature, however. This case illustrates that 'malignant features' in esophageal melanocytosis should be interpreted with caution.