These findings are consistent with a type of heritable keratoderma called pachyonychia congenita (also called twenty-nails dystrophy). It is easy to mistake this unusual cause of thickening nails with a more common cause: onychomycosis.
Pachyonychia congenita describes a set of disorders driven by heritable defects in 1 of 5 keratin genes. The disorder is often transmitted in an autosomal dominant fashion, although a third of patients are thought to have a spontaneous mutation.1 These gene changes can cause 1 or multiple dystrophic nails, thickened nail beds, natal teeth, thick plantar or palmar nodules or plaques, and hearing difficulties. Some patients may have symptoms at birth, while other patients do not develop symptoms until later in life.1
There is currently no cure for pachyonychia congenita. Patients with suspected heritable keratoderma benefit from referral to Medical Genetics and a dermatologist who is comfortable treating keratodermas. Patients can obtain free genetic testing, educational material, and additional resources through pachyonychia.org.
This patient was prescribed topical urea 40% cream that was to be applied to the feet nightly, until the nodules became less painful. He was also evaluated for pressure-offloading orthotics. Nails may be treated with topical urea lacquer nightly until patients are satisfied with the appearance, although this patient chose to forgo the lacquer.
Text courtesy of Jonathan Karnes, MD, medical director, MDFMR Dermatology Services, Augusta, ME. Photos courtesy of Jonathan Karnes, MD (copyright retained).