Cutaneous Warts

Pathogenesis and How Lesions Develop

Viral Attachment and Cell Proliferation

• Entry into the basal layer: HPV particles bind heparan sulfate proteoglycan receptors on basal stem cells via the L1 capsid protein.
• Proliferation and elongated dermal papillae: Viral DNA drives abnormal host-cell division, increasing the number of spinous-layer cells (acanthosis) and pushing the epidermis up into finger-like projections (papillomatosis).
• Koilocyte formation: In the upper epidermis, virus assembly produces koilocytes, cells with shrunken, dark-staining nuclei surrounded by a clear halo.

Capillary Proliferation and Thrombosis

• The virus causes capillaries in the dermal papillae to lengthen and enlarge, reaching close to the surface to feed the growing lesion.
• Pressure or local inflammation blocks these capillaries, forming tiny clots (thrombosed capillaries). Clinically, these are the black dots or dark red streaks typical of warts.

Clinical Types of Cutaneous Warts

Common Warts (Verruca Vulgaris):

• Main causes: HPV 2, 4, 7, 27, 57.
• Appearance: Raised, dull gray, yellow-gray or skin-colored papules with a rough, fissured, cauliflower-like surface, from 2 mm to over 1 cm.
• Location: Backs of the hands, fingers, nail folds, elbows and lower legs.

Plantar and Mosaic Warts:

• Main causes: HPV 1 (deep type, myrmecia), HPV 2 and 4 (superficial type).
• Appearance:
  • Solitary warts (myrmecia): A thick keratin plug pushed deep into the sole by body weight, ringed by hard callus and very painful when walking.
  • Mosaic warts: Dozens of superficial warts merge into one large keratotic plaque, less painful but highly resistant to treatment.

Flat Warts (Verruca Plana):

• Main causes: HPV 3, 10, 28.
• Appearance: Small (1–3 mm), slightly raised papules with a smooth, flat top, pale pink, yellow-brown or skin-colored.
• Location and Koebner phenomenon: Usually on the face, neck and forearms. Papules often line up along scratch marks.

Filiform Warts:

• Appearance: Thin, elongated growths that project well above the skin, like threads or slender fronds.
• Location: Around the eyes, eyelids, lips, nose and neck. They bleed or get injured easily during shaving or face washing.

Periungual and Subungual Warts:

• Appearance: Rough keratotic growths along the nail folds or extending under the nail plate.
• Complications: Cracking, pain and nail deformity (nail dystrophy); they are hard to reach with conventional treatments.

Differential Diagnosis of Hyperkeratotic Skin Lesions

Our Diagnostic Process at Haute-Derma

Clinical Assessment and Pinch Test: The doctor squeezes the lesion from side to side to distinguish a plantar wart (painful on pinching) from a corn (painful when pressed straight down on the center).

Digital Dermoscopy:

• Common and plantar warts: A papillomatous surface, complete interruption of skin lines and scattered red or gray-black dots (thrombosed papillary capillaries).
• Flat warts: Well-defined pinkish-gray areas with a slightly rough surface and evenly spaced small red dotted vessels.

Biopsy (Suspicious or Treatment-Resistant Cases): Indicated for lesions that grow unusually or raise concern for malignant change. Histology shows marked hyperkeratosis, acanthosis, elongated dermal papillae and koilocytes in the upper spinous layer.

Treatment and Cosmetic Optimization at Haute-Derma

Specialist Topical and Chemical Treatments

• Salicylic acid 16.7%–40% solution (or combined with lactic acid): Applied daily after soaking in warm water and filing down the surface keratin. It softens and loosens the keratin and triggers a mild local inflammatory response.
• Trichloroacetic acid (TCA 80%–90%): Dabbed precisely onto filiform or small warts, coagulating protein and destroying the virus-laden tissue.
• Topical immune stimulants:
  • Imiquimod 5%: Applied 3 times a week for flat facial warts or periungual warts. It prompts Langerhans cells to release cytokines that attack HPV.

Dual Laser Treatment at Haute-Derma

• Long-pulsed 1064 nm Nd:YAG laser (Step 1: shutting down the feeding vessels): The laser targets oxyhemoglobin in the enlarged capillaries of the dermal papillae, and its photothermal energy coagulates these feeding vessels. Cut off from its blood supply, the wart regresses and falls off from within without leaving a large open wound.
• Superpulse CO2 laser (Step 2: precise vaporization of the keratin mass): The 10,600 nm wavelength precisely removes the remaining hyperkeratotic tissue, with depth controlled to the micron. Ultra-short Superpulse mode destroys diseased tissue efficiently without the heat buildup that causes depressed scars.
• Liquid Nitrogen Cryotherapy: Liquid nitrogen (−196°C) is sprayed to freeze warts on the hands and feet, creating an epidermal blister that lifts the wart away.

Skin Recovery and Preventing Recurrence

• Apply a repair cream with zinc oxide, panthenol (vitamin B5) and madecassoside for 7–10 days after the procedure.
• Use a broad-spectrum sunscreen on the face after flat wart treatment to prevent post-inflammatory hyperpigmentation (PIH).