A malignant epithelial neoplasm which is confined to the epithelial layer without evidence of further tissue invasion. The disease is in situ carcinoma (MONDO_0004647, a Monarch Disease Ontology term). Also known as: carcinoma in situ, carcinoma, in situ, malignant, epithelial tumor, in situ, malignant, intraepithelial carcinoma, non-invasive carcinoma, stage 0 disease.