Kyrle's disease (hyperkeratosis follicularis et parafollicularis in cutem penetrans)

Introduction

A disorder of keratinization characterized keratotic papules on the extremities & trunk, most commonly associated with diabetes mellitus & renal failure, but also without associated disease.

Etiology

• associated disorders
  • diabetes mellitus & renal failure (most common)
  • hepatic insufficiency
  • congestive heart failure
  • hypothyroidism
  • hyperlipoproteinemia
• idiopathic

Epidemiology

• uncommon
• 3rd to 7th decade, rarely in infants & children
• females > males

Pathology

• invaginating epidermal keratotic plug
  • may perforate epidermal basement membrane into the dermis
• focal parakeratotic & basophilic debris
• marked thinning or perforation of the epidermis
• neutrophil infiltrating in the dermis beneath keratotic plugs
• lymphocyte & histiocyte dermal infiltrate around the lesions

Clinical manifestations

• insidious, asynchronous development of lesions
• early lesions may be asymptomatic to slightly pruritic
• older lesions may be painful, especially with applied pressure
• traumatized lesions may become secondarily infected
• initial lesion is small hyperkeratotic papule
• lesions enlarge to form papules, nodules & plaques with hyperkeratotic caps/plugs
• removal of the hyperkeratotic plug leaves a crater within a depressed nodule or papule
• resolution of lesions generally leaves atrophic scars
• larger lesions may become hyperpigmented
• lesions are scattered or clustered
• enlarging lesions may coalesce
• distribution
  • extensor surface of extremities
  • trunk
  • buttocks
  • mucous membranes are not involved

Laboratory

skin biopsy

Differential diagnosis

• prurigo nodularis
• multiple keratoacanthomas
• perforating folliculitis
• elastosis perforans serpiginosa
• reactive perforating collagenosis
• atypical mycobacterial infection
• verruca vulgaris

Management

• topical agents
  • tretinoin gel or cream
  • keratolytic agents such as salicylic acid
• oral etretinate
  • high dose
  • need for chronic administration precludes practicality
• cryo-, electro- or CO2 laser surgery
  • resultant scar formation
  • may prevent recurrence of lesions at the treatment site
• prognosis
  • chronic disorder
  • lesions may heal with atrophic scar
  • local recurrence is common

More general terms

• skin disease (dermatologic disorder, dermatopathy, dermatosis)

Additional terms

• hyperkeratosis