The pathogenetic role of rod‐shaped bacteria containing intracellular granules in the vellus hairs of a patient with perioral dermatitis: A comparison with perioral corticosteroid‐induced rosacea

The cause of perioral dermatitis is still unknown. We previously reported that rod-shaped bacteria (RB) containing intracellular granules were detected in cases of perioral dermatitis at a high incidence. The aim of this study was to study further the role of RB in perioral dermatitis. Altogether 10 patients with perioral dermatitis and eight patients with perioral corticosteroid-induced rosacea, who were referred to our department from 2009 to 2014, were examined for the presence of RB, using the tape-stripping toluidine blue method. RB were detected on the surfaces of the roots of vellus hairs from lesions in nine of the 10 patients with perioral dermatitis. In contrast, RB were not detected in any of the eight patients with perioral corticosteroid-induced rosacea. No RB were found in the perioral areas of other types of facial dermatitis, including atopic dermatitis and seboerrheic dermatitis or in 16 healthy controls. We treated four of the patients with perioral dermatitis with minocycline hydrochloride and five with cefcapene pivoxil hydrochloride hydrate. Three of the patients with perioral dermatitis who were treated with minocycline hydrochloride were cured in 3 to 8 weeks, while the five patients treated with cefcapene pivoxil hydrochloride hydrate were cured in 2 to 9 weeks. These results strongly suggest that RB (possible fusobacteria) play an important role in perioral dermatitis and that this is probably a distinct clinical entity from corticosteroid-induced rosacea. Cefcapene pivoxil hydrochloride hydrate seems to be an effective treatment for perioral dermatitis associated with RB.