Idiopathic eruptive macular pigmentation

A skin condition characterized by asymptomatic hyperpigmented macules

Idiopathic eruptive macular pigmentation (IEMP) is a rare dermatological condition characterized by the sudden appearance of asymptomatic, hyperpigmented macules on the skin. These macules are typically dark brown and can vary in size and shape. The condition is idiopathic, meaning its exact cause is unknown, and it is not associated with any systemic symptoms or underlying diseases.

Clinical Presentation

IEMP primarily affects children and young adults, although cases have been reported in individuals of all ages. The condition is marked by the abrupt onset of multiple, non-scaly, hyperpigmented macules. These lesions are usually distributed symmetrically on the trunk, neck, and proximal extremities. The face is generally spared.

The macules are flat, with well-defined borders, and do not cause any itching or discomfort. Over time, the pigmentation may fade, but this process can take several months to years. In some cases, the pigmentation may persist indefinitely.

Pathogenesis

The exact pathogenesis of idiopathic eruptive macular pigmentation is not well understood. Histopathological examination of the lesions typically reveals increased melanin in the basal layer of the epidermis, with no significant increase in the number of melanocytes. There is also an absence of any inflammatory infiltrate, which distinguishes IEMP from other pigmented dermatoses.

Diagnosis

The diagnosis of IEMP is primarily clinical, based on the characteristic appearance and distribution of the lesions. A skin biopsy may be performed to rule out other conditions with similar presentations, such as post-inflammatory hyperpigmentation, lichen planus, or fixed drug eruption.

Differential Diagnosis

The differential diagnosis for IEMP includes:

• Post-inflammatory hyperpigmentation
• Lichen planus pigmentosus
• Fixed drug eruption
• Erythema dyschromicum perstans
• Melasma

Management

There is no specific treatment for idiopathic eruptive macular pigmentation, as the condition is benign and self-limiting. Patients are usually reassured about the benign nature of the condition. In some cases, topical depigmenting agents or chemical peels may be used to hasten the resolution of pigmentation, although their efficacy is variable.

Prognosis

The prognosis for individuals with IEMP is excellent, as the condition is benign and does not lead to any complications. The pigmentation may resolve spontaneously over time, although this can take several years.

Related Pages

• Hyperpigmentation
• Dermatology
• Melanin
• Skin biopsy