Idiopathic guttate hypomelanosis
While the exact cause is unknown, IGH has been hypothesized to be ultraviolet (UV) induced. Other contributing factors that have been suggested include aging, trauma, genetic factors, and autoimmunity.
While IGH occurs more commonly in lighter skin phototypes, it does occur in all skin colors, and it appears more prominent in individuals with darker skin.
L81.9 – Disorder of pigmentation, unspecified
1717003 – Idiopathic guttate hypomelanosis
Differential Diagnosis & Pitfalls
- Hypopigmented flat warts – These are perceptibly raised.
- Hypopigmented seborrheic keratoses – Also perceptibly raised.
- Tinea versicolor – Typically scaly and limited to the upper trunk and shoulder.
- Pityriasis alba – Usually seen in atopic children; lesions are ill-defined.
- Pityriasis lichenoides chronica (PLC) – Usually seen in a younger patient population than IGH and found on sun-protected skin; in young patients with dark skin phototypes, PLC may present as hypopigmented macules, and PLC may resolve with guttate leukoderma.
- Leukodermic macules of Darier disease.
- Postinflammatory hypopigmentation – Can be distinguished by preceding history of dermatitis.
- Vitiligo – Lesions are depigmented, often acral, and coalesce to form larger depigmented patches.
- Leukoderma punctata – 0.5- to 1.5-mm achromic macules that follow psoralen plus UVA (PUVA) or UVB therapy.
- Lichen sclerosus – Shows a "tissue paper" atrophic appearance with telangiectasia; not confined to sun-exposed skin.
- Atrophie blanche – Favors the distal shins and ankles but is usually atrophic and surrounded by telangiectasia.