A challenging diagnosis: Case report of oral metastasis from gastric adenocarcinoma mimicking pyogenic granuloma

RATIONALE: Oral metastases occur more commonly in bone, but can also manifest in soft tissues and eventually resemble a reactive lesion. Few cases of oral metastases mimicking reactive lesions in soft tissues have been reported to date. PATIENT CONCERNS: We report a metastasis of gastric carcinoma (GC) to the oral mucosa without bone involvement in a 43 yom clinically and microscopically mimicking a reactive lesion. The patient related that the lesion had 1 month of evolution, and the ulcerated area suggested the lesion was related to trauma. DIAGNOSES: The histopathological examination of the lesion revealed an exuberant granulation tissue with few neoplastic cells, and the initial diagnosis of pyogenic granuloma was considered. In a second analysis, clusters of clear cells morphologically similar to degenerating mucous cells or macrophages, positive for Cytokeratin (CK)-20, and CDX2 were found. At the moment, it was confirmed the presence of a primary GC in the patient. INTERVENTIONS: A palliative radiotherapy/chemotherapy was started. OUTCOMES: However, the patient died 3 months after the diagnosis of oral metastasis. LESSONS: This report highlights the importance of careful clinical and microscopic examinations in cases of oral metastasis that may mimic a reactive lesion.