What is the Difference Between IGH and Vitiligo?

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Idiopathic Guttate Hypomelanosis (IGH) and vitiligo are both skin conditions that cause hypopigmentation, or decreased pigmentation, in certain areas of the skin. However, there are key differences between the two:

IGH:

  • IGH spots are usually hypopigmented, not completely free of pigment as seen in vitiligo.
  • IGH spots typically form on sun-exposed areas like the forearms, shins, and chest.
  • IGH patches tend to be more noticeable on darker skin but may be more common in people with lighter skin.
  • The etiology of IGH remains unknown, and several hypotheses exist.
  • IGH occurs in all races and skin types.

Vitiligo:

  • Vitiligo is characterized by patches of light, depigmented skin.
  • It is an autoimmune disorder that causes depigmentation, or loss of skin pigment, leading to light or white patches of skin.
  • Vitiligo is characterized by the complete absence of melanocytes in the affected regions.

It is crucial to distinguish IGH lesions from vitiligo early in the disease course because, in contrast to vitiligo, lesions of IGH do not progress.

Comparative Table: IGH vs Vitiligo

Idiopathic guttate hypomelanosis (IGH) and vitiligo are both skin conditions that cause depigmentation, but they have different characteristics and appearances. Here is a table summarizing the differences between IGH and vitiligo:

Feature Idiopathic Guttate Hypomelanosis (IGH) Vitiligo
Appearance Multiple, small, round, depigmented macules Depigmented patches that can be irregular in shape and size, with darker borders
Histopathology Hyperkeratosis, atrophic epidermis, flattened rete ridges, decreased melanin content, and reduced numbers of melanocytes Flattening of the epidermis, complete loss of melanin and melanocytes as the lesion ages
Dermoscopy Amoeboid macules (depigmented to hypopigmented) with skip areas (areas of retained melanin in the basal layer) Dermoscopic findings may vary; the presence of skip areas is not a common feature in vitiligo
Diagnostic Aids Dermoscopy can improve the diagnostic accuracy Histopathology and dermoscopy can be helpful for differentiation

While both conditions have overlapping clinical and histopathological features, IGH is often characterized by the presence of multiple small, round, depigmented macules, while vitiligo typically presents as irregularly shaped depigmented patches with darker borders. Additionally, the presence of skip areas in the basal layer of the epidermis is a specific finding in IGH.