Rhinoscleroma Presenting as Recalcitrant Frontal Sinusitis: A Case Report

Abstract Rhinoscleroma (RS) is a chronic granulomatous disease that primarily affects the nose and upper respiratory passages, including the nasopharynx, larynx, trachea, and bronchi. It spreads via the droplet route and predominantly affects individuals from low socioeconomic backgrounds, often associated with poor domestic hygiene and overcrowding. The etiological agent of RS is the Gram-negative bacillus Klebsiella rhinoscleromatis , also known as Frisch bacilli or Diplo bacillus. It often follows a viral infection and mostly resides intracellularly, making it difficult to isolate in laboratory settings. Here, we present a case of a 58-year-old male who experienced persistent nasal blockage even after functional endoscopic sinus surgery (FESS) for noninvasive nasal polyposis. Endoscopic findings revealed crust and debris in the postoperative FESS cavity. A follow-up computerized tomography paranasal sinus scan demonstrated mild mucosal thickening with obliteration of the right antrum. Mucosal thickening was noted in the left maxillary sinus, bilateral ethmoid, and frontal sinuses, along with mild bone sclerosis. The patient underwent revision FESS, nasalization, and left DRAF IIB. He was started on mupirocin, budesonide nasal douching, and montelukast. Antifungal therapy was also given despite the negative biopsy as the patient had persistent sinusitis with bone sclerosis. Histopathology ruled out fungal or acid-fast bacilli infection. Ultimately, a granulomatous lesion over the left frontal recess was identified as RS (possibly K. rhinoscleromatis ). Combination therapy with ciprofloxacin and doxycycline led to symptomatic improvement and endoscopic clearance. This underscores that RS also needs to be included in the differential diagnosis of patients with persistent sinusitis and crust formation even in regions like southern India where this condition is uncommon.