Last reviewed: 23 Dec 2021
Last updated: 17 Dec 2021



History and exam

Key diagnostic factors

  • presence of risk factors
  • scaling scalp lesions
  • patchy alopecia
  • erythematous, scaling skin lesions with central clearing
  • erythematous, scaling rash with follicular pustules in beard or moustache
  • erythematous, annular patches on face
  • vesicles and scaling of hands
  • fissuring, maceration, and scaling in the interdigital spaces of the fourth and fifth toes
  • chronically scaly, hyperkeratotic plantar skin with erythema of the soles, heels, and sides of the feet
  • folliculitis with nodules

Other diagnostic factors

  • thickened nail with subungual hyperkeratosis, onycholysis, and white-yellow to brown discoloration
  • small, white speckled patches on the surface of the nail plate with crumbling nail
  • lymphadenopathy
  • black-dot alopecia
  • milky white nail plate
  • area of leukonychia in the proximal nail plate

Risk factors

  • exposure to infected people, animals, or soil
  • exposure to fomites, including hat, combs, hairbrushes, and upholstery
  • chronic topical or oral corticosteroid use
  • HIV
  • diabetes mellitus and other metabolic disorders
  • occlusive clothing
  • hot, humid weather
  • obesity
  • hyperhidrosis
  • frequenting public bathing areas while barefoot
  • deformities of the feet
  • recurrent trauma to the skin
  • contact sports
  • atopic dermatitis
  • positive family history
  • peripheral vascular disease

Diagnostic investigations

Investigations to consider

  • dermoscopy
  • fungal culture
  • polymerase chain reaction (PCR)
  • Wood lamp examination (ultraviolet light)

Emerging tests

  • reflectance confocal microscopy

Treatment algorithm



Antonella Tosti, MD

Professor of Clinical Dermatology

Dermatology and Cutaneous Surgery

University of Miami Health System



AT received honorarium and travel reimbursement from Valeant, PharmaDerm, and Polichem, and is on the speaker bureau for PharmaDerm.


Dr Antonella Tosti would like to gratefully acknowledge Dr Keira L. Barr and Dr Barry L. Hainer, the previous contributors to this topic.


KLB declares that she has no competing interests. BLH is on the speaker bureaus for the vaccine programmes of Merck and Sanofi-Pasteur pharmaceutical companies.

Peer reviewers

Nanette Silverberg, MD

Clinical Professor of Dermatology

Columbia University College of Physicians and Surgeons

New York City



NS declares that she has no competing interests.

Christina M. Gelbard, MD

Department of Dermatology

UT Dermatology

Health Science Center of Houston




CMG declares that she has no competing interests.

Use of this content is subject to our disclaimer