Importance of differential diagnosis of EBV mucocutaneous ulcer and EBV-positive diffuse large B-cell lymphoma: A case report.

Rationale: Epstein-Barr virus mucocutaneous ulcers (EBVMCUs) were officially recognized as a clinicopathologic entity in the 2017 revision of the World Health Organization classification, which often occurs in the elderly or in immunosuppressive condition presented as an isolated ulcerative lesion. EBVMCUs are defined as "shallow, sharply circumscribed, mucosal or cutaneous ulcers with underlying polymorphous infiltration." It mostly involves oral mucosa, but some appear in skin or gastrointestinal tract. Typically, patients with EBVMCUs display a slow disease progression and may even undergo spontaneous regression.

Patient Concerns: This report describes the case of a 76-year-old woman who visited our outpatient clinic with the chief complaint of inflammation and ulceration on lower labial, lower right lingual gingiva seemed like acute necrotizing ulcerative gingivitis, and malignancy.

Diagnoses: She was diagnosed with EBVMCU after tissue biopsy.

Interventions: Since most oral ulcerations usually appear in nonspecific form, it is important to check thoroughly for any underlying immunosuppressive systemic conditions and laboratory test results in case of viral infection. But she has no remarkable underlying immunosuppressive disorder.

Outcomes: For this patient, she was initially diagnosed with EBVMCU and showed spontaneous healing, but then relapsed after 4 to 6 months. The patient was re-diagnosed as EBV-positive diffuse large B-cell lymphoma (EBV-positive DLBCLs) after re-biopsy.

Lessons: EBVMCU shows similar symptoms to malignant lesions or acute necrotizing ulcerative gingivitis but shows spontaneous healing. However, in case of EBV-positive DLBCLs, failing to detect and treat the disease in its early stages can lead to a fatal outcome. Thus, this case report highlights the differential diagnosis and appropriate treatment of EBVMCU and EBV-positive DLBCLs.