# A Rare Case of Sinonasal Actinomycosis

## TL;DR

A rare case of sinus infection caused by Actinomyces bacteria is described, highlighting the importance of considering this diagnosis in patients with maxillary sinus symptoms.

## Contribution

This paper presents a rare clinical case of sinonasal actinomycosis and emphasizes the role of endoscopic surgery in diagnosis and treatment.

## Key findings

- A 79-year-old woman with a six-month history of nasal symptoms was diagnosed with sinonasal actinomycosis.
- Endoscopic surgery revealed granulation tissue and caseous purulent material, with histopathology confirming Actinomyces colonies.
- The patient recovered fully after surgery and short-term antibiotic treatment without recurrence at six months.

## Abstract

Actinomycosis is an infection caused by Actinomyces species--filamentous, gram-positive, anaerobic bacteria commonly found in the oral cavity. Although cervicofacial involvement is more frequently encountered, actinomycosis may involve the sinonasal tract and present with imaging findings that resemble neoplastic lesions. We report a 79-year-old woman who presented with a six-month history of left-sided purulent nasal discharge and nasal obstruction. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed an expansile soft-tissue lesion with bone destruction in the left maxillary sinus, suggestive of odontogenic sinusitis. We performed endoscopic sinus surgery (ESS) combined with endoscopic modified medial maxillectomy (EMMM), which revealed marked granulation tissue and caseous purulent material without evidence of malignancy. Histopathological examination confirmed colonies consistent with Actinomyces. The patient received cefazolin (1 g/day) for two days postoperatively as standard perioperative antibiotic prophylaxis only, resulting in complete recovery without recurrence at six months. This case highlights the importance of considering Actinomyces infection in patients with unilateral maxillary sinus disease following dental procedures. Advances in endoscopic techniques, such as EMMM, allow complete debridement with minimal invasiveness and may reduce the need for prolonged therapeutic antibiotic therapy.