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I have white spots on my skin ! Diagnosis: Idiopathic Guttate Hypomelanosis

13 November 2019

Idiopathic guttate hypomelanosis (IGH) is a benign, asymptomatic pigmentation disorder that presents as multiple small, hypopigmented macules on the skin. It is seen in up to 80% of individuals over the age of 70. 

Who can be affected by IGH pigmentation disorder? 

  • IGH can be seen in all races and skin types but it is particularly common in older fair skinned individuals who have had a history of sun exposure. 
  • However, it is more of a concern to dark-skinned patients due to its striking clinical appearance. 
  • Both men and women are affected equally later in life, but women tend to be affected more frequently at a younger age. 
  • Although IGH is considered an acquired condition, it has been reported in families. 

what causes IGH – Idiopathic guttate hypomelanosis? 

The cause of guttate hypomelanosis is unknown, but normal senescence and exposure to the sun are thought to play a role. Within the lesions of IGH, keratinocytes lack melanin due to a defect in melanosome transfer and decreased melanin synthesis. There is also a reduction in the total number of melanocytes in IGH, but not a complete absence as is seen in vitiligo. No significant structural abnormality of the melanocytes has been shown in lesions of IGH. Clinically, the lesions of IGH present as flat, white macules measuring 1 to 3 mm. The lesions have no epidermal or textural component. The shins and forearms are the sites most commonly affected. The individual lesions can increase in number but do not increase in size and do not depigment over time. The hypopigmented lesions are also not predisposed to skin cancer. 

How is IGH diagnosed and managed? 

The diagnosis of idiopathic guttate hypomelanosis is clinical. The most common differential diagnoses to consider include vitiligo, pityriasis alba, tinea versicolor and hypopigmented flat warts. IGH is essentially a cosmetic condition. The management of IGH involves educating patients of its benign nature, and that it is not related to, nor does it evolve into vitiligo. 

Encouraging general sun safe behaviour can help in preventing further lesions of IGH. There are no uniformly successful treatments for IGH. Treatments that have been used, albeit with limited success, include topical steroids, tretinoin and pimecrolimus. 

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Dr. Samir Gupta

Dermatologist

Dr. Gupta MD, FRCPC is a board-certified Dermatologist practicing in the greater Toronto area. He completed medical school at the University of Toronto and dermatology training at the University of Chicago and Harvard University. He is the Clinical Director of HeartLake Cosmetic Dermatology with 15 years of experience treating patients from all over Canada.