Can you identify this rash?

THIS rash is difficult to diagnose clinically unless included in differential diagnoses of a groin or genital rash.

It looks red and scaly, like psoriasis, or crusted, as in impetigo or Hailey-Hailey disease. However, this is extramammary Paget’s disease, where tumour cells are confined to the epidermis.

These cells can arise from an underlying apocrine gland tumour or from an adjacent carcinoma such as bladder, prostate or rectum. A punch skin biopsy can differentiate.

A tinea infection should show central clearing with a spreading scaly edge.

This patient