Rosai-Dorfman-type histiocytes occur in eosinophilic chronic rhinosinusitis and potentially play a role in disease initiation and persistence

Limited Sinonasal Rosai‐Dorfman Disease Presenting as Chronic Sinusitis

Aims

The sinonasal tract is a common extranodal site for Rosai–Dorfman disease (RDD). Recently, histiocytes with features of RDD were identified in the clinical setting of chronic sinusitis. This study evaluates whether this phenomenon should be considered part of the RDD spectrum or classified separately as RDD‐like histiocytes.

Methods and results

We prospectively collected 13 cases showing histological features of RDD in chronic sinusitis patients and identified 14 with similar findings (3.5%) via retrospective review of 403 sinus contents over 2 years. All 27 cases displayed nodular aggregates of eosinophilic histiocytes with intermixed lymphoplasmacytic inflammation, prominent eosinophils and emperipolesis. The histiocytes were positive for S100 protein and cyclin D1 and negative for CD1a and CD207. All patients presented with severe chronic sinusitis without tumour formation or systemic symptoms. Twelve patients with follow‐up (55%) required repeat sinus surgery compared with just 43 other sinusitis patients evaluated (11%); features of RDD were present in their additional specimens. Two cases that underwent targeted next‐generation sequencing (20%) had oncogenic mutations in NF1 and KEAP1.

Conclusions

Overall, these findings confirm diagnostic histological and immunohistochemical features of RDD in a subset of chronic sinusitis specimens. While patients uniformly lack systemic involvement or tumefactive growth, they have a high risk of recurrent sinus disease. Although the relatively subtle nature of the findings raises consideration of separate classification, the presence of occasional oncogenic mutations and evidence of consistent MAPK/ERK pathway activation via cyclin D1 positivity suggests that this phenomenon represents a unique limited manifestation of RDD.

Inflammatory and Infectious Lesions of the Sinonasal Tract

The sinonasal tract is frequently affected by nonneoplastic inflammatory diseases. Inflammatory lesions of the sinonasal tract can be divided into 3 main categories: chronic rhinosinusitis, which encompasses a heterogeneous group of entities, all of which result in mucosal inflammation with or without polyps-eosinophils; infectious diseases; and autoimmune diseases and vasculitides, which can result in midline necrosis and facial deformities. This article reviews the common inflammatory lesions of the sinonasal tract with emphasis on infectious diseases, vasculitis, iatrogenic, and diseases of unknown cause. Many of these lesions can result in midline destruction and result in facial deformity.