Allergic fungal sinusitis with cranial base erosion

Background. Allergic fungal sinusitis (AFS) usually follows a slow, nonaggressive course. However, massive bone destruction can occur, with extension of the disease process outside of the confines of the sinuses. Methods. Our series of 28 cases of AFS was reviewed. We identified 6 cases of AFS with definite radiographic evidence of skull base erosion. Results. Histologic diagnostic criteria for AFS were present in all 6 cases. All patients were managed with surgery, most recently conservative endoscopic surgery. An earlier patient underwent dural resection. Antibiotics were used in all patients, but no antifungal agents were administered. No patient has had a permanent neurologic complication, although one was seen with abducens palsy. There have been no cerebrospinal fluid (CSF) leaks. All 6 cases also had orbital bone erosion, but none has had permanent ophthalmologic sequelae. All patients were initially suspected to have a neoplastic disease. Conclusions. We propose a new diagnostic entity, 'skull base allergic fungal sinusitis' (SBAFS), which incorporates the histologic diagnostic criteria of AFS with the computed tomographic (CT) criteria of bone erosion. Biopsy is necessary to rule out invasive fungus or tumor. Otolaryngologists, ophthalmologists, and neurosurgeons should be familiar with SBAFS so that systemic antifungal agents, craniotomy, and dural resection-which might initially appear necessary-can be avoided. Endoscopic surgical debridement and drainage combined with topical steroids can lead to resolution of disease, even in the presence of marked bone erosion and cranial neuropathy.