Idiopathic Guttate Hypomelanosis Workup

Updated: Aug 14, 2017
  • Author: Christopher R Gorman, MD; Chief Editor: William D James, MD  more...
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Laboratory Studies

Idiopathic guttate hypomelanosis should be diagnosed on clinical grounds. A Wood light examination could be helpful in revealing unsuspected involvement. Dopa staining can be useful because dopa-positive melanocytes are decreased.



In atypical cases of idiopathic guttate hypomelanosis, a biopsy may be indicated. Dermatoscopic examination may aid in diagnosis. Peripheral lesion findings include amoeboid, featherlike, and petaloid patterns described in lesions of idiopathic guttate hypomelanosis. [8, 9]


Histologic Findings

Several light and electron microscopic studies have revealed a characteristic pathologic picture for idiopathic guttate hypomelanosis. Typical histologic findings are epidermal atrophy of the actinic type, a patchy decrease or absence of melanocytes and melanin, flat rete ridges, and basket weave hyperkeratosis. Skip areas of retained melanin can help histologically differentiate this condition from other disorders of pigmentation. [10]