A case of Epstein-Barr virus-positive mucocutaneous ulcer of the hypopharynx: a mimicker of hypopharyngeal squamous cell carcinoma.

Epstein-Barr virus-positive mucocutaneous ulcer (EBVMCU) is a new disease, described by the World Health Organization in 2017. It has been recognized as a specific type of immunodeficiency-associated lymphoproliferative disorder. Since patients with EBVMCU present with only cutaneous or mucosal ulcers, it is difficult to clinically distinguish them from carcinoma. A 72-year-old man, who took methotrexate (MTX) (12 mg/week) for rheumatoid arthritis, was referred to our hospital because endoscopy revealed an ulcerated mass in the left pyriform sinus, suggesting hypopharyngeal squamous cell carcinoma. Contrast-enhanced computed tomography and magnetic resonance imaging revealed an ill-defined mass in the left pyriform sinus without lymphadenopathy in the head and neck region. A biopsy of the ulcerative lesion in the hypopharynx was performed, and lymphoproliferative disease was suspected, based on the histopathological findings. Two weeks after MTX withdrawal, the lesions in the hypopharynx disappeared. The patient was diagnosed with EBVMCU, based on the clinical and histopathological findings. This is the first case report of EBVMCU of the hypopharynx. EBVMCU should be considered as a differential diagnosis in immunocompromised patients with hypopharyngeal mucosal ulcers without lymph node or organ involvement.