Several years ago, this 50-year-old woman developed a rash under her breasts. It comes and goes, but in hot weather, the condition is particularly uncomfortable and accompanied by an objectionable odor.

The rash was declared a yeast infection by a previous provider, but it failed to respond to several different prescription and OTC anti-yeast creams, lotions, and oral medications. The patient is in no distress but is somewhat agitated about the lack of effective treatment. Referral to dermatology is arranged.

History-taking reveals a family history of skin problems. However, neither the patient nor any family member has ever seen a dermatologist before now, and no provider has ever biopsied the affected skin.

On examination, the florid, white, scaly rash under the patient’s breast stands out in stark contrast to her type V skin. The rash is bilateral, and the affected area precisely aligns with the inframammary fold of each breast. There are sharp margins and uniform moist scaling.

No other areas of skin are affected. However, seven of her 10 fingernails exhibit longitudinal white and red streaks, and several nails have triangular nicks in the edges. The roof of her mouth is studded with fleshy nodules measuring 0.6 to 1 cm. Several pits are seen on her palms.

A sample of the affected inframammary skin is taken via punch biopsy and submitted to pathology. The report shows acantholysis with focal dyskeratotic keratinocytes. Intraepidermal separation is seen throughout the specimen.