Appearance Readings

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Acne - Essential Reading

Pustules from Principles of Dermatology

Acne Pathogenesis

Acne Vulgaris

Clinical Types

  • Comedonal
  • Inflammatory/pustular
  • Nodulocystic

Therapeutic Options

  • Keratolytic
  • Retinoids – topical, systemic
  • Antibiotics – topical, systemic
  • Hormonal modulators – oral contraceptives, spironolactone

Differential Diagnosis

  • Hormonal acne
  • Steroid acne
  • Bacterial folliculitis
  • Pityrosporum folliculitis
  • Demodex folliculitis
  • Rosacea
  • Hidradenitis suppurativa
  • Acne keloidalis

Acne vulgaris - Summary

Diagnostic classification Comedonal Inflammatory Nodulocystic
Clinical findings
  • Open comedone
  • Closed comendones
  • Open comedones
  • Closed comedones
  • Pustules
  • Papules
  • PIH
  • Open comedones
  • Closed comedones
  • Pustules
  • Papules
  • Nodules
  • PIH
  • Pitted scars
Follicular occlusion? Y Y Y
Excess sebum production? Y Y Y
Inflammatory? N Y Y
Scarring? N
  • Minimal
  • PIH is common
 Y
Therapeutics
  • Topical retinoids
  • Salicyclic acid
  • Topical retinoids
  • Salicyclic acid
  • Topical abx
  • Systemic abx
  • Androgen inhibition
 Systemic retinoids (isotretinoin)
Hormonal influence Y Y Y
Genetic influence Y Y Y
Other influences Y
  • Dairy
  • Androgen containing supplements
 Y

Hidradenitis suppurative - Essential Reading

Folliculitis from Principles of Dermatology

Pathogenesis

Grading Systems

Progression and Staging

  • Initially inflammatory nodules and sterile abscesses arise in the axillae, groin, perianal, and/or inframammary areas; often very painful.
  • With time sinus tracts and hypertrophic scars develop; chronic, malodorous drainage also occurs.
  • Complications may include anemia of chronic disease, secondary amyloidosis, lymphedema, fistulas, arthropathy, and the rare development of SCCs within the chronic scars.
  • DDx: staphylococcal furunculosis, Crohn disease, granuloma inguinale, mycetoma, and scrofuloderma (a form of tuberculous lymphadenitis with cutaneous extension).

Hurley Staging System

The Hurley system is one of several scoring systems for HS. Using the Hurley system will help direct your physical exam and observational skills.

  • Stage I – one or more abscesses with no sinus tract or scar formation
  • Stage II – one or more widely separated recurrent abscesses, with sinus tract and scar formation
  • Stage III – multiple interconnected sinus tracts and abscesses throughout an affected region; more extensive scarring

Letter from Yale Medical Student

The letter was written by a medical student after interviewing a patient hospitalized for hidradenitis suppurative. It is included here with the author's permission. Any patient identifiers have been removed.

Download Letter

Optional Readings

  • Review the A&D lectures: Structure/Function of the Skin, Seeing and the Skin, Epidermal Derivatives
  • Review American Academy of Dermatology Basic Dermatology Curriculum Acne and Rosacea module.