Pityriasis versicolor in the aged: a clinical investigation and epidemiological survey in 190 elderly hospitalized patients.

190 subjects over 60 yrs of age, hospitalized for long stays were checked for scaling and hyperpigmented patches of P. versicolor. 20 patients (10.5%) showed no clinical lesions; 170 patients (89.5%) showed scaling and/or hyperpigmented patches of which 13 patients (6.8%) on direct microscopic exam showed hyphae and yeasts of M. furfur, 64 (33.6%) only globular forms of P. orbiculare and 113 cases (59.4%) showed no fungal elements. Wood's light examination showed that 38 subjects (20%) were 6 positive for M. furfur and 23 for P. orbiculare while in the other 9 no fungal elements were observed on microscopic exam. Whereas 48/132 patients negative to Wood's light were positive for yeasts on microscopic exam (false negative). This study indicates that P. versicolor is not rare in the elderly and that Wood's light examination is not diagnostic. There was no relationship between P. versicolor and underlying illness.