Allergic Mucin With and Without Fungus

Context.—Allergic mucin, a lamellated collection of inspissated inflammatory debris, has been a hallmark of allergic fungal sinusitis. While its identification is a clue for pathologists to search for fungi, and directs clinicians toward specific therapy and follow-up, recent reports describe cases with allergic mucin but without concomitant fungus. The absence of such organisms in otherwise typical allergic mucin brings into question the role of fungi in allergic fungal sinusitis. Objectives.—To study clinical and pathologic differences between patients with allergic mucin in surgical nasal resection specimens and to elucidate the role of fungus in allergic sinusitis. Design.—Patients with histologic evidence of allergic mucin, with and without fungus, were identified and retrieved from the surgical pathology files of a tertiary-care institution. The patients were separated into 2 groups for analysis, and their clinical and pathologic findings were reviewed and compared. Setting.—Tertiary-care institution. Patients.—All patients who underwent sinus mucosal resection between 1992 and 1998. Results.—Clinical presentation and radiographic findings were similar in both groups. Incidence, age, and gender distribution were similar to data reported previously. However, the amount of allergic mucin was much greater in the group with fungus than in the group without fungus, which to our knowledge is an unreported observation to date. Conclusion.—The presence of allergic mucin is not unique to allergic fungal sinusitis, but rather is the result of a process that could have other etiologies. While perhaps not always causative to the disease, the fungus continues to fuel the process and is likely an entrapped bystander. Allergic fungal sinusitis is more appropriately termed allergic mucinous sinusitis or eosinophilic mucinous rhinosinusitis.