Clear cell renal cell carcinoma metastasizing to the oral cavity: A diagnostic challenge of a case revealing an unusual clinical presentation

Objective Diagnosing lesions with unusual clinical presentation can be challenging, mostly for cases in which the inclusion of oral metastasis in the differential diagnosis is necessary. Materials and Methods A 55‐year‐old man complaining of a large mass in the oral cavity was referred to the Hospital Dentistry Service. The patient reported bleeding episodes and pain, with a 5‐month evolution. Intraoral examination revealed a 5 cm tumour with purplish‐red and ulcerated focal areas at the right buccal mucosa. Differential diagnosis included malignant mesenchymal tumours, lymphoproliferative lesions, and metastasis of an occult primary lesion. Two biopsies were conducted, with the first one presenting an intense haemorrhage, and the second performed under general anaesthesia and difficult bleeding control. Results Histologic and immunohistochemical analysis diagnosed a clear cell carcinoma infiltration. A whole‐body CT scan reveals a renal tumour with multiple metastasis sites in the abdomen and bones. Metastatic clear cell renal cell carcinoma was finally confirmed, and the patient was followed with palliative care for 4 months. Conclusion A challenging diagnosis of a rare metastatic lesion in the oral cavity was conducted after two procedures under difficult bleeding conditions.