BackgroundTraumatic ulcerative granuloma with stromal eosinophilia (TUGSE) is a rare self-limiting condition of the oral mucosa. The lesion manifests as an isolated ulcer that can be either asymptomatic or associated with mild to severe pain, and in most cases, it affects the tongue. TUGSE lesions may mimic malignancy such as squamous cell carcinoma, CD30 positive lymphoproliferative disorder, or infectious diseases such as primary syphilis, tuberculosis, or Epstein-Barr virus mucocutaneous ulcer. Histologically dominating cells are lymphocytes, histiocytes, and eosinophils.Case presentationWe describe a TUGSE case of a patient with a solitary ulcer on the lower left retromolar buccal plane. Upon presentation, the patient reported a swelling on the buccal mucosa of the left lower jaw since 1 year with rapid growth over the last days and mild pain while chewing. The diameter of the intraoral lesion on the lower left retromolar buccal plane was approximately 4 × 3 cm; the lesion presented as indurated base with a central superficial ulceration of 2 × 1 cm, indicative for a malignant process. Histologically, the ulceration showed an expanding, infiltrative, and vaguely granulomatous morphology, involving the superficial mucosa and the fatty tissue, and extended between the deep striated muscle fibers. The lesion was rich in lymphocytes, histiocytes, and eosionophils intermingled with activated T-blasts without phenotypic abnormalities. TUGSE was then diagnosed based on the phenotype (especially the lacking expression of CD30, the retained T-cell phenotype, and the absence of Epstein-Barr virus), the clinical presentation, and the morphology. Twenty-six months after diagnosis, no recurrence of the ulceration was seen.ConclusionsAs TUGSE may mimic malignancy or infectious diseases, biopsy is mandatory and should be combined with thorough clinical examination. A screening for infectious diseases (mainly syphilis, Epstein-Barr virus, and HIV infections) must be performed routinely. In most cases, the lesions resolve spontaneously, obviating the need of further actions other than clinical follow-up. The pathogenesis of TUGSE lesions is still under debate, although local traumatic events and a locotypic immune response have been suggested to be major contributing factors.