How is a penile skin scraping performed?

How to Perform a Penile Skin Scraping

Penile skin scrapings are generally not recommended for diagnosing most penile lesions, as they may not be sufficiently representative for accurate diagnosis. 1

When Skin Scrapings Are NOT Appropriate

• For suspected penile cancer or suspicious lesions: An incisional or excisional biopsy is required rather than scrapings, as punch biopsy or scrapings may not be sufficiently representative for accurate histological diagnosis and staging 1
• For most sexually transmitted infections: Cotton-wool or Dacron swabs are preferred over scrapings for collecting specimens from penile lesions 2

When Skin Scrapings MAY Be Appropriate

The primary indication for actual scraping technique on penile skin is for suspected scabies or parasitic infestations:

Scabies Scraping Technique

1. Preparation: Place a drop of mineral oil on a sterile scalpel blade and allow some oil to flow onto the papule 1

2. Scraping procedure: Scrape vigorously 6 to 7 times to remove the top of the papule (tiny flecks of blood should be visible in the oil) 1

3. Mite extraction: Use the flat side of the scalpel to apply pressure to the side of the papule to push the mite out of the burrow 1

4. Specimen transfer: Transfer the oil and scrapings directly onto a glass slide using the scalpel or an applicator stick—never use a swab, as it will absorb the material and not release it onto the slide 1

5. Adequate sampling: For best results, scrape 20 papules 1

Preferred Alternative Techniques for Common Penile Lesions

For Vesicular Lesions (Suspected HSV)

• Open vesicles with a sterile needle first 1, 2
• Collect vesicular fluid with a cotton-wool or Dacron swab 1, 2
• Vigorously swab the base of the lesion to obtain epithelial cells 2
• Place specimen in viral transport medium 2

For Ulcerative Lesions (Suspected Syphilis)

• Use a cotton-wool or Dacron swab to collect specimens from the lesion base 2
• The Kimura scraper may be used for sampling ulcer bases, but this is sterilized by heating in a flame and allowed to cool before use 1
• Collect specimens for direct fluorescent antibody testing or NAAT 2

For Suspected Malignancy

• Obtain a pretreatment biopsy (punch, excisional, or incisional) when malignancy is not clinically obvious 1
• Biopsy is mandatory to determine tumor grade and assist in risk stratification 1

Critical Pitfalls to Avoid

• Do not rely on scrapings for diagnosing penile cancer: Up to 20% of patients with penile intraepithelial neoplasia harbor invasive disease that would be missed by superficial sampling 1
• Avoid calcium alginate swabs: These interfere with viral recovery for STD testing 2
• Do not use scrapings for routine STD diagnosis: Clinical diagnosis without laboratory confirmation is unreliable, as genital HSV is difficult to differentiate from syphilis and other causes of genital ulceration 2