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Pachyonychia congenita
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Pachyonychia Congenita

Pachyonychia congenita is a rare genetic condition primarily affecting the skin and nails, characterized by extremely painful calluses on the soles of the feet and thickened, abnormally shaped nails.

Overview & Symptoms

Pachyonychia congenita is a condition that primarily affects the skin and nails. The signs and symptoms of this condition usually become apparent within the first few years of life.

Key features of the condition include:

  • Plantar keratoderma: Very painful calluses on the soles of the feet. These usually begin to form in childhood when kids first start to walk, and can make walking painful or impossible. Blisters, bundles of blood vessels and nerves (neurovascular structures), or a deep itch may develop under or near the calluses, increasing pain and discomfort.
  • Hypertrophic nail dystrophy: Thickened and abnormally shaped fingernails and toenails. The number of affected nails varies.
  • Palmar keratoderma: Thickened, painful skin on the palms of the hands.
  • Oral leukokeratosis: Thick, white patches on the tongue and inside of the cheeks.
  • Follicular keratoses: Bumps that develop around hair follicles on the elbows, knees, and waistline.
  • Cysts in the armpits, groin, back, or scalp.
  • Palmoplantar hyperhidrosis: Excessive sweating on the palms and soles.
  • Steatocystomas: Widespread cysts filled with an oily substance called sebum that normally lubricates the skin and hair.
  • Prenatal or natal teeth, which are teeth present at birth or in early infancy.
  • Pain in one or both ears when beginning to eat or drink.
  • Involvement of the voice box (larynx), causing hoarseness or breathing problems.

Researchers used to classify pachyonychia congenita as either PC-1 or PC-2 based on the genetic cause and pattern of signs and symptoms. However, because the signs and symptoms of these types overlap considerably, pachyonychia congenita is now classified into five types based on the gene that is altered.

Frequency

Pachyonychia congenita is a very rare disorder, although its exact prevalence is unknown.

Causes & Genetic Factors

Variants (also called mutations) in the KRT6A, KRT6B, KRT6C, KRT16, or KRT17 genes cause pachyonychia congenita.

The classification is based on the specific gene altered:

  • KRT6A variants cause PC-K6a
  • KRT6B variants cause PC-K6b
  • KRT6C variants cause PC-K6c
  • KRT16 variants cause PC-K16
  • KRT17 variants cause PC-K17

All of these genes provide instructions for making tough, fibrous proteins called keratins. These proteins form networks that provide strength and resilience to the tissues that make up the skin, hair, and nails.

Variants in keratin genes alter the structure of keratin proteins, making them unable to form strong, stable networks within cells. Without this network, skin cells become fragile and easily damaged, making the skin less resistant to friction and minor trauma. Normal activities such as standing and walking cause skin cells to break down, resulting in severe, painful blisters and calluses. Defective keratins also disrupt the growth and function of cells in the hair

Frequently Asked Questions

Topical keratolytics such as 40% urea cream applied nightly can soften hyperkeratotic plaques, followed by gentle mechanical debridement with a pumice stone or a foot file after a warm soak. For refractory pain, a podiatrist may prescribe oral analgesics (e.g., NSAIDs) or a low‑dose gabapentin to target neuropathic components. Custom orthotic shoes with deep heel cups and soft silicone inserts reduce pressure points and prevent new callus formation.
Systemic retinoids (e.g., acitretin 0.25 mg/kg/day) have been shown to reduce nail thickness in some patients, but they require monitoring for liver toxicity and lipid changes. Topical keratolytic nail lacquers (e.g., 40% urea) can be tried first. Surgical nail removal is reserved for severe pain or functional impairment and should be performed by a dermatologist or hand surgeon experienced with PC.
Because pachyonychia congenita is autosomal‑dominant, a single pathogenic variant in KRT6A, KRT6B, KRT16, or KRT17 confirms the diagnosis. A certified genetic counselor can arrange targeted gene panel testing using a blood or saliva sample. Results clarify recurrence risk (50 % for each future pregnancy) and enable cascade testing of siblings and parents. Counseling also discusses reproductive options such as pre‑implantation genetic diagnosis.
First, clean the area with sterile saline; avoid harsh antiseptics that may delay healing. Apply a non‑adherent dressing (e.g., silicone‑gel sheet) topped with a hydrocolloid pad to maintain a moist environment. Change dressings daily or when soiled. If infection is suspected (redness, increased pain, purulent drainage), seek medical evaluation for possible oral antibiotics.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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