Skin Wart Anatomy
To better understand warts, it helps to understand the anatomy of the skin.
The skin contains three main layers:
- The superficial layer that makes up the surface of the skin
- It is composed of skin cells and can be divided into 5 layers based on cell type.
- The top layer of the epidermis, the stratum corneum, is made of dead, flat skin cells that shed about every 2 weeks.
- The thickness of the epidermis varies, according to location: it is very thick over the soles of the feet, and very thin over the ears.
- Lies beneath the epidermis
- Also varies in thickness depending on the location of the skin. It is .3 mm on the eyelid and 3.0 mm on the back.
- The dermis is composed of 2 layers that contain a connective tissue called collagen
- The dermis contains blood vessels, nerves, sweat glands, and hair follicles.
- The number of structures in the dermis varies, according to location.
- The dermis under the arms contains more sweat glands and hair follicles than the dermis on the back.
- Subcutaneous layer:
- Mainly fat and connective tissue.
- Contains blood vessels and nerves.
- Agius E, Mooney JM, Bezzina AC, Yu RC. Dermojet delivery of bleomycin for the treatment of recalcitrant plantar warts. J Dermatolog Treat. 2006;17(2):112-6. 
- Bacelieri R, Johnson SM. Cutaneous warts: an evidence-based approach to therapy. Am Fam Physician. 2005 Aug 15;72(4):647-52. 
- Focht DR 3rd, Spicer C, Fairchok MP. The efficacy of duct tape vs cryotherapy in the treatment of verruca vulgaris (the common wart). Arch Pediatr Adolesc Med. 2002 Oct;156(10):971-4. 
- Lewis TG, Nydorf ED. Intralesional bleomycin for warts: a review. J Drugs Dermatol. 2006 Jun;5(6):499-504. 
- Mullen BR, Guiliana JV, Nesheiwat F. Cimetidine as a first-line therapy for pedal verruca: eight-year retrospective analysis. J Am Podiatr Med Assoc. 2005 May-Jun;95(3):229-34.