A 13-year-old male was evaluated for possible scalp infection. The patient's mother reported white scaly patches on the scalp and red rash on the patient's body folds and genitals for multiple years. She described a strong family history of hereditary mucoepithelial dysplasia (HMD) in herself, multiple maternal aunts and uncles, and maternal grandfather, and stated that the family had been studied and described in a publication by Witkop et al in 1979. 1 Physical examination revealed coalescing patches of alopecia involving the entire scalp and bilateral eyebrows with a background of white scaly plaques.Residual hairs appeared thin and brittle (Figure 1). Bright red, welldefined, psoriasiform plaques in scrotal and intertriginous areas, as well as thin pink to red plaques involving all dorsal proximal interphalangeal joints, were observed. Generalized xerosis with follicular