Actinomycosis is a chronic, rare bacterial infection caused by Actinomyces israelii. It primarily affects the oropharynx, gastrointestinal tract, and genitourinary system, with the oropharynx being the most common site. Risk factors for the development of this infection include breaches in the oral cavity, chronic infections in the head and neck region, and immunosuppression. Diagnosing actinomycosis can be challenging because of its clinical presentation, which often mimics other benign and malignant disorders. Here, we report the case of a 57-year-old woman who underwent a COMMANDO (combined mandibulectomy and neck dissection operation) followed by combined radiotherapy and chemotherapy. This treatment was initiated after identifying a lesion on the tongue extending to the lower gums suggestive of squamous cell carcinoma (pT4aN0M0 staging) in an anatomopathological study. Five months later, the patient developed pain and paresthesia in the region of the surgical wound and presented with a granulomatous and vegetating lesion in the lower right alveolar ridge. Pathological analysis identified this new lesion as compatible with Actinomyces sp. However, a subsequent analysis, conducted after an attempt to treat the infection, revealed that the lesion was a recurrence of the carcinoma.