Pathology quiz case 2. Ecthyma gangrenosum (EG)

Aggressive necrotizing pseudomonal sinonasal infections

BACKGROUND

Pseudomonas aeruginosa is a gram-negative bacterium frequently implicated in recalcitrant sinonasal infections, especially in immunocompromised hosts. We report 6 cases of rapidly progressive pseudomonal acute rhinosinusitis producing tissue necrosis and, in certain cases, cranial nerve palsies.

METHODS

Retrospective review of 6 patients with aggressive necrotizing sinonasal infections treated at 4 tertiary academic medical centers with sinonasal cultures growing P. aeruginosa in the absence of other pathology.

RESULTS

A total of 6 patients were identified. In all cases, there was tissue necrosis that appeared to mimic an invasive process such as mucormycosis, prompting urgent surgical intervention. Pathologic analysis revealed fibropurulent exudates in backgrounds of positive P. aeruginosa cultures without evidence of invasive fungal organisms or malignancy. Four of the 6 patients presented with cranial nerve palsies, with 3 patients having vision changes and 3 complaining of trigeminal neuropathy. Four of 6 patients improved clinically over time after surgery and antibiotic therapy; 1 remains in follow-up without complete improvement and 1 has succumbed to other causes.

CONCLUSION

P. aeruginosa is a tenacious organism that is frequently associated with severe, recalcitrant sinonasal infections. We report the first case series of necrotizing sinonasal infections caused by this organism, and illustrate that, in rare cases, P. aeruginosa may mimic and behave like life-threatening conditions such as fulminant invasive fungal sinusitis or malignancy.