Comparison between Malassezia Folliculitis and Non-Malassezia Folliculitis

BACKGROUND Among the various types of folliculitis, differentiation of Malassezia folliculitis (MF) from other forms of folliculitis is important because it is usually treated with antifungal agents. OBJECTIVE We attempted to find a method to enhance the detection rate of MF, and examined the differences in the clinical manifestation between MF and non-MF (NMF). METHODS We performed a retrospective study involving patients with folliculitis who were previously diagnosed with MF or NMF on the basis of serial tissue sectioning and diastase-Periodic acid-Schiff (d-PAS) staining findings. The clinical features of MF and NMF were compared. RESULTS Among a total of 100 folliculitis patients, 20 were diagnosed with MF and 80 with NMF. Tissues from the 80 patients with NMF were sectioned serially into 10 slices and stained with hematoxylin and eosin stain; among these, 10 had many round-to-oval yeast organisms in the hair follicles that confirmed MF. Finally, d-PAS staining was used to detect the presence of yeast in the NMF slides. Notably, among the 70 d-PAS-stained samples, yeast organisms were found in 6 samples, confirming MF. As a result, the diagnosis of 16 patients changed from NMF to MF. Compared with NMF, MF showed major involvement of the trunk and low involvement of the face and legs as well as male predilection. CONCLUSION Physicians should consider serial sectioning and/or d-PAS staining of folliculitis lesions, particularly of those on the trunk of male patients, even if no yeast organisms are detected initially.