Skin nontumor

Infectious disorders

Hidradenitis suppurativa



Topic Completed: 23 November 2021

Minor changes: 23 November 2021

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PubMed Search: Hidradenitis suppurativa[TI] skin pathology free full text[SB]

Matthew Franklin, M.D.
Stephen Somach, M.D.
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Cite this page: Franklin M, Somach S. Hidradenitis suppurativa. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumorhidradenitis.html. Accessed December 3rd, 2021.
Definition / general
  • Chronic inflammatory disorder of pilosebaceous apocrine unit characterized by nodules, abscesses, fistulae and sinus tracts, with scarring
  • Most commonly affects the axillae and groin, among other areas of young adults
Essential features
  • Inflammatory disorder of terminal hair bearing skin, most commonly in the axillae and groin, manifesting with nodules, open comedones and draining sinuses with prominent scarring
  • Risk factors include female sex, obesity, smoking and family history
  • Associated with metabolic syndrome, adverse cardiovascular events and other¬†inflammatory disorders, e.g. psoriasis
  • Follicular occlusion is the first step in pathogenesis, followed by epithelial rupture with ensuing inflammation, foreign body reaction, occasionally apocrine involvement and bacterial colonization
  • Effective treatment (may involve antibiotics, biologic or surgical measures) is often challenging
Terminology
ICD coding
  • ICD-10: L73.2 - hidradenitis suppurativa
  • ICD-11:¬†ED92.0 - hidradenitis suppurativa
Epidemiology
  • Estimated prevalence between 0.00033% and 4.10% (Exp Dermatol 2019;28:769)
  • Prevalence in U.S. population recently estimated to be 0.10% (JAMA Dermatol 2017;153:760)
    • More than twice as common in women
    • Highest among patients aged 30 - 39 years
    • Prevalence is more than 3 times greater in African American patients than Caucasian patients
  • Onset before 11 years of age estimated to account for 2% of cases (Pediatr Dermatol 1999;16:292)
Sites
Pathophysiology
Etiology
Clinical features
Diagnosis
Laboratory
Radiology description
  • Ultrasound (Skin Res Technol 2020;26:11)
    • Thickened dermis
    • Widened hair follicles
    • Tracts
    • Hypoechoic fluid pockets
    • Decreased surrounding tissue echogenicity
    • Abscess
Radiology images

Images hosted on other servers:
Hidradenitis nodule (a) and abscess (b)

Hidradenitis nodule (a) and abscess (b)

Case reports
Treatment
Clinical images

Images hosted on other servers:

Axilla

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Matthew Franklin, M.D.
Dermal sinus tract

Dermal sinus tract

Sinus tract with rupture

Sinus tract with rupture

Suppurative and granulomatous inflammation

Suppurative and granulomatous inflammation

Follicular occlusion and inflammation

Follicular occlusion and inflammation

Perifollicular abscess

Perifollicular abscess

Epithelial remnants with inflammation

Epithelial remnants with inflammation

Molecular / cytogenetics description
Sample pathology report
  • Right proximal thigh, excision:
    • Dermal epithelial lined sinus tract with cyst rupture and surrounding acute and chronic inflammation, consistent with hidradenitis suppurativa
Differential diagnosis
  • Other entities within the follicular occlusion tetrad (acne conglobata, pilonidal cyst and dissecting cellulitis) have similar histopathology
  • Clinicopathologic correlation, especially with anatomic site, is necessary
  • Ruptured follicular cyst / folliculitis:
    • Similar histopathology, except dissecting tracts would not be expected
  • Soft tissue infection:
    • Special stains for microorganisms, as well as tissue cultures, help to exclude this possibility
Additional references
Board review style question #1
Dermal sinus tract Follicular occlusion and inflammation


A 25 year old woman with diabetes presents for draining boils in her axillae and groin. Abnormalities in which of the following cutaneous structures is thought to initiate the pathogenic cascade leading to the inflammatory sequelae of this disease?

  1. Apocrine glands
  2. Arrector pili muscle
  3. Eccrine glands
  4. Infundibular follicular epithelium
  5. Sebaceous glands
Board review style answer #1
D. Infundibular follicular epithelium

Comment Here

Reference: Hidradenitis suppurativa
Board review style question #2
Which of these is a risk factor for the development of hidradenitis suppurativa?

  1. Alcohol consumption
  2. Low BMI
  3. Male sex
  4. Smoking
Board review style answer #2
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