Actinomycosis of the right maxillary sinus mimicking the recurrence of adenoid cystic carcinoma – case presentation

Introduction: Adenoid cystic carcinoma (ACC) is a rare malignancy originating from the salivary glands. It accounts for about 1–5% of all malignancies in the head and neck region. It was first described in 1853 and 1854. The main prognostic factors are tumor extension, degree of malignancy, lymph node metastases, infiltration of neural tissue and the margin of healthy tissues. Actinomycosis is a specific inflammation caused by gram-positive anaerobic bacteria Actinomyces israelii. It was first described by Von Hacker in 1885. These bacteria co-create the bacterial flora of the oral cavity, throat, digestive tract and genitourinary system. Infection with this pathogen triggers formation of abscesses and fistulas. Case report: A case of a 75-year-old woman treated for ACC is presented. During the follow-up examination, the patient presented symptoms of a local recurrence of ACC, which was suspected until the second histopathological examination that pointed to actinomycosis of the right maxillary sinus. Conclusion: Due to frequent recurrences of ACC after treatment, follow-up in these patients should be long-term, and any worrying symptoms should be diagnosed for potential recurrence.