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Collection of dermatological disorders

Last updated: September 22, 2021

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This article covers various dermatological disorders, including sebaceous and epidermoid cysts, cat scratch disease, cutaneous mastocytosis, miliaria, nummular eczema, angiokeratoma, dyshidrotic eczema, livedo reticularis, xeroderma pigmentosum, pseudofolliculitis barbae, and albinism.



Types of miliaria
Miliaria crystallina Miliaria rubra Miliaria profunda
  • Most common type
  • Usually seen in adult men in tropical climates, who have had repeated episodes of miliaria rubra
Level of sweat duct blockage
Clinical features
  • Clear 1–2 mm vesicles with no erythema

  • Callus: thick, toughened skin caused by repeated mechanical pressure and friction
  • Clavus: a painful, hyperkeratotic lesion with a center core (corn) caused by frictional forces and trauma

  • Description: chronic facial dermatitis affecting the perioral region
  • Epidemiology: primarily children and women 20–45 years of age [15]
  • Etiology
    • Unknown
    • Presumably caused by regular application of (glucocorticoid) creams and/or cosmetics
  • Clinical features
    • Erythema with grouped papules and pustules
    • Dry skin with painful burning and a sensation of tightness
    • No residual scarring after resolution
  • Treatment
  • Description: a rheumatological, spondylarthritic disease with simultaneous occurrence of synovitis, acne, pustulosis, hyperostosis, and osteitis
  • Clinical features
  • Etiology: unknown
  • Diagnostics
  • Treatment: primarily symptomatic

Types of livedo reticularis [16]
Physiological livedo (idiopathic livedo) Pathological livedo (livedo racemosa)
  • A vascular syndrome that can be caused by either benign autonomic dysregulation of cutaneous perfusion or pathological obstruction of blood vessels
  • Autonomic dysregulation (functional disturbance) causing slowed cutaneous perfusion in response to external factors (i.e., cold)
  • Localized obstructions slow the blood flow (organic disturbance)
Clinical features
  • Symmetrical livedo reticularis (regular, small, round) of the extremities and sometimes the trunk
  • Triggered by cold, regresses after application of warmth
  • Warmth, sauna, alternating cold and warm baths
  • Treat the underlying disease
  • Improves with age
  • Depends on the underlying disease (usually more difficult to treat)

Livedo reticularis that does not regress after application of warmth is indicative of an underlying vascular disease and requires treatment.

  • Description: inflammatory skin reaction in response to short hair that becomes entrapped within the skin
  • Etiology
    • Usually occurs due to shaving (also known as razor bumps)
    • Most common in African American men because the hair shafts typically form tight coils
  • Pathophysiology
    • Extrafollicular penetration: Hair enters the interfollicular epidermis after it exits the follicular orifice.
    • Transfollicular penetration: Hair penetrates the dermis before exiting the follicular orifice.
  • Clinical features
  • Diagnostics: a clinical diagnosis
  • Treatment

  • Definition: a rare, very aggressive vascular malignancy, arising from endothelial cells of blood or lymphatic vessels [20]
  • Epidemiology: peak incidence age > 70 years [20]
  • Etiology [20]
  • Clinical features [21][22]
    • Location
      • More common in sun-exposed areas
      • Usually occur on the head, neck, and breast
      • May involve the internal organs (e.g., hepatic angiosarcoma)
    • Lesion
      • Blue/purple-colored with a bruise-like appearance
      • Later stage: hemorrhage or ulceration
      • High variability in appearance
  • Treatment [22]
    • Complete resection with wide margins
    • Resection may be complicated by the aggressive course of the disease and delayed diagnosis.
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