Quantitative variations in distribution of Pityrosporum orbiculare on clinically normal skin.

The lipophilic yeast Pityrosporum orbiculare has been cultured quantitatively, in 10 volunteers, from clinically normal skin on the chest, back, upper arm, lower leg, and dorsal aspect of the hand. The highest count was on the back (mean 333/cm2) and chest (mean 327/cm2). This was statistically significant higher than on the upper arm (mean 21/cm2), lower leg (mean 13/cm2), and dorsal aspect of the hand (mean 2/cm2). The variations in number of P. orbiculare parallels both regional variations in sebum excretion and the distribution of tinea versicolor lesions.