Light microscopy of hair may be an aid to some, fairly rare, paediatric diagnoses. At Great Ormond Street Children’s Hospital, London over a 15 year period (1989–2004) 322 hair samples were examined by light microscopy in the pathology department (

) . Almost half (49%) showed abnormalities and in half of those (25% of the total) the changes pointed to a specific diagnosis.

The largest group of patients (108) was of …