We describe a case of positive Epstein-Barr virus (EBV) mucocutaneous ulcer and discuss the morphology, immunophenotype, differential diagnosis and clinical presentation of this newly-defined entity in WHO 2017. The patient presented with a non-healing mucosal ulcer in the oral cavity. Histologically it showed a polymorphous infiltrate composed predominantly of small lymphocytes and other inflammatory cells admixed with scattered large atypical cells with large irregular or lobated nuclei and abundant cytoplasm. Binucleated cells or cells with smudged nuclei are also occasionally observed. By immunohistochemistry and EBER-ish, the large atypical cells were positive for CD30, paired box domain gene 5 (PAX5), CD79a, EBER and occasionally positive for CD20. The background small lymphocytes were CD3 positive T-cells. Epstein-Barr virus-positive mucocutaneous ulcer can histologically and immunophenotypically resemble or overlap with classical Hodgkin lymphoma or large B-cell lymphoma, which makes the interpretation difficult and may cause an overcall in diagnosis for this indolent disease. A correct diagnosis requires correlation with clinical information such as age, history of immunosuppressive therapy, location and behavior of the lesion.