Origin and spread of allergic fungal disease of the nose and paranasal sinuses

Although expansion of bony walls occurs in allergic fungal disease of the n ose and paranasal sinuses by increased mucus secretion and fungal growth, t he latter is apparently confined to the lumen and does not invade the tissu es. Nevertheless, spread of the disease process from paranasal sinuses to o rbit, cheek and intracranial cavity is well described. An imaging and histo pathological study was carried out in 16 cases to determine how the disease originates and spreads. The infection starts in the nasal cavity, the lume n of a sinus or in a seromucinous gland or duct. A thin vascular zone of in tense allergic inflammation surrounds the infected mucin. Erosion of bone t akes place focally, probably by substances produced by the inflammatory tis sue, allowing intromission by the thin vascular layer together with its und erlying fungus-containing mucus and so extension of the disease process thr ough the eroded bone.