Exams and Tests

• When the scalp is examined with a Wood lamp that transmits ultraviolet light, the base of the hair shaft will light up a blue-green fluorescent band if Microsporum species is present. This is due to deposits of metabolic by-products that this species leaves. Because this species is no longer common in the United States, this technique is less useful.

• More commonly, the doctor can diagnose scalp ringworm with a visual inspection and by observing the symptoms present. However, a culture and scrapings examined under a microscope are needed to confirm the diagnosis.

• The following are methods of collecting tissue samples for microscopy:
  
  
  • Scraping the scalp with a surgical blade and removing the hair with a needle and forceps
    
    
  • Running a toothbrush over the scalp about 10 times to collect the scales and hair (this is the best method)
    
    
  • Cotton swabs
    
    
  • Moistened gauze

• Once tissues have been collected, a 10-15% solution of KOH (potassium hydroxide) is added and the slide is studied under a microscope to look for fungal spores. This method is fast, but it is effective in finding present fungal spores only 50% of the time.

• The best method of diagnosis is culture. The collected specimen is placed in a medium that provides fungal food to see if growth takes place. This method naturally takes more time, and an answer takes 7-10 days.