Tonsillar Actinomycosis Simulating an Oropharyngeal Neoplasm in a 67-Year-Old Man With Diabetes Mellitus, Hypertension, and Ischemic Heart Disease: A Case Report From King Faisal General Hospital, Hofuf, Saudi Arabia.

Actinomyces species constitute part of the normal microbial flora of the oral cavity. When mucosal integrity is disrupted, these organisms can produce invasive cervicofacial infections. Tonsillar actinomycosis can closely mimic an aggressive oropharyngeal malignancy in elderly patients with significant comorbidities. A 67-year-old man with type 2 diabetes mellitus, hypertension, and ischemic heart disease presented with a chronic progressively enlarging right tonsillar mass accompanied by throat discomfort. Clinical assessment and computerized tomography imaging scan revealed a 42 mm × 24 mm × 47 mm avidly enhancing, lobulated, exophytic lesion centered in the right tonsillar fossa with apparent extension toward the tongue base and pterygoid musculature, raising strong suspicion for malignancy. Surgical excision demonstrated a well-circumscribed, non-infiltrative mass with an intact capsule. Histologic examination showed filamentous bacterial colonies and sulfur granules typical of actinomycosis on hematoxylin and eosin, PAS (periodic acid-Schiff), and GMS (Grocott methenamine silver stains). An extensive immunohistochemical panel (cytokeratin, CD (cluster of differentiation) 3, CD20, CD45, desmin, and p16) was negative, effectively excluding squamous cell carcinoma, lymphoma, and mesenchymal neoplasms. The patient received postoperative antibiotics and analgesics; symptoms resolved promptly, and he remained disease-free on follow-up. Early surgical removal combined with careful histopathologic evaluation (including special stains and immunohistochemistry) and extended penicillin-based antimicrobial therapy permits accurate diagnosis, avoids unnecessary radical oncologic procedures, and yields excellent outcomes.