Background: Gastrointestinal actinomycosis is rare, difficult to recognize, and often mimics malignancy. Gastric involvement is exceptional and is described in only a small number of reports (1–4). Postoperative sites, such as gastric anastomoses, are particularly susceptible to Actinomyces infection due to altered mucosal integrity (5).
Case Presentation: A 76-year-old man with a history of gastric cancer treated surgically and with chemotherapy more than five years earlier, considered cured, underwent routine endoscopic surveillance. Endoscopy revealed a normal esophagus and loops, but the laterolateral gastric anastomosis showed irregular, ulcerated, infiltrative lesions with yellowish exudates, raising strong suspicion of tumor recurrence. Multiple biopsies were taken.
Histopathology demonstrated foveolar hyperplasia, ulceration, intestinal metaplasia, granulation tissue, mixed inflammatory infiltrate, and Helicobacter pylori. Critically, Actinomyces colonies were identified on one fragment, with no dysplasia or malignancy. Findings were diagnostic of anastomotic actinomycosis.
Management and Outcome: The patient received standard therapy consisting of high-dose intravenous penicillin, followed by prolonged oral amoxicillin, as recommended for gastrointestinal actinomycosis (1). Endoscopic follow-up showed complete healing of anastomotic lesions. Persistent H. pylori infection was treated subsequently with eradication therapy.
Discussion: Actinomycosis can masquerade as malignancy due to its infiltrative pattern, fibrosis, ulceration, and the presence of sulfur granules. Several gastric cases initially suspected as cancer were later reclassified as actinomycosis on biopsy (2–4). Anastomotic involvement is documented in postoperative infections and requires prolonged penicillin-based therapy (5). Early recognition avoids unnecessary oncologic interventions.
Conclusion: Anastomotic actinomycosis is an important differential diagnosis for suspicious anastomotic lesions in patients with prior gastric cancer. Histopathology is essential for accurate diagnosis, and penicillin-based therapy ensures excellent outcomes.