Eruptive Hypomelanosis

Eruptive Hypomelanosis

Eruptive hypomelanosis is a childhood exanthem of presumed infectious etiology characterized by an acute and brief eruption of monomorphic hypopigmented macules and papules associated with fever, rhinitis, pharyngitis, and lymphadenitis. ICD-10 Code: B09.0

This condition occurs predominantly in children between the ages of 1 and 9 years, more often in boys. The prevalence is unknown, with the first cases described in India and Hong Kong.

The etiopathogenesis is unknown. The presence of a prodromal period, systemic symptoms (fever, lymphadenitis, pharyngitis), mini-epidemics in families and daycare centers, and the rapid spontaneous remission of the rash suggest an infectious nature, most likely viral. To date, the causative agent has not been identified.

After a brief prodrome, eruptions suddenly appear 5-14 days later as multiple monomorphic, round or circular, isolated hypopigmented macules or flat papules, 3-8 mm in diameter (usually almost the same size), with well-defined borders, often covered with scaly scales.

The rash is symmetrical and typically occurs on the extensor surfaces of the limbs (forearms, thighs), rarely on the face, and is accompanied by low-grade fever, catarrhal symptoms, and regional lymphadenitis (neck or axillary). It is not pruritic.

Over 7-10 days, the rashes rapidly spread to adjacent areas of the body (elbows, knees, backs of hands, and feet), then the process stabilizes. Systemic symptoms resolve spontaneously within a week, while eruptions may persist for 2 to 8 weeks.

Diagnosis is based on history and clinical presentation. Complete blood count may show mild lymphocytosis. Wood's lamp and KOH tests are recommended to rule out pityriasis versicolor.

  • Vitiligo
  • Pityriasis versicolor
  • Clear cell papulosis
  • Pityriasis alba
  • Idiopathic guttate hypomelanosis
  • Progressive macular hypomelanosis
  • Post-inflammatory hypopigmentation

This condition is self-limiting and does not require treatment. Symptomatic therapy may be considered for systemic symptoms if present.