Abstract
The sinonasal masses can underlie a universe of pathologies, both benign and malignant. Despite its rarity, Diffuse Large B-cell Lymphoma is the high-grade and nonepithelial lesion most frequently described in the nasal cavity and paranasal sinuses. On the other hand, Immunoglobulin G4 related disease may occur as sinonasal benign lesions with a tendency to bone erosion. Both these pathologies, opposite in nature, are involved in the study. Herein, the case of a patient with a vascular manifestation of IgG4-related disease and a unilateral sinonasal mass is described. The aim of this work is to describe the characteristics of these lesions and highlight the importance of the differential diagnosis, stressing the need to perform a biopsy in all the unilateral sinonasal masses.