Progressive Macular Hypomelanosis (PMH): Treatment, Symptoms, Causes, Diagnosis, and Differentiation from Vitiligo

Content: 

• What is Progressive Macular Hypomelanosis?
• Progressive Macular Hypomelanosis Symptoms
• Progressive Macular Hypomelanosis Causes
• Progressive Macular Hypomelanosis Diagnosis
• Progressive Macular Hypomelanosis Treatment
• Progressive Macular Hypomelanosis vs Vitiligo

What is Progressive Macular Hypomelanosis?

Progressive Macular Hypomelanosis (PMH) is a skin pigmentation disorder that presents as non-scaly, hypopigmented (light-colored) patches primarily on the trunk. These patches are usually round or oval and symmetrically distributed, often affecting the back, abdomen, and chest.

Unlike other skin conditions, PMH does not cause itching or inflammation. It is a benign condition and typically occurs in young adults, especially females with darker skin tones. The condition progresses slowly over time and is often mistaken for other pigment disorders such as vitiligo or tinea versicolor.

Progressive Macular Hypomelanosis Symptoms

Symptoms of Progressive Macular Hypomelanosis include pale, flat, and non-itchy patches on the skin. These patches usually appear on the central parts of the trunk and may gradually increase in number and size.

These hypopigmented lesions do not cause discomfort and are purely cosmetic in concern. The affected skin areas retain normal texture and sensation. The condition is often more noticeable in people with darker skin tones due to the contrast in pigmentation.

Progressive Macular Hypomelanosis Causes

Several potential causes of Progressive Macular Hypomelanosis have been identified:

• Overgrowth of Cutibacterium acnes (formerly Propionibacterium acnes) bacteria in hair follicles
• Hormonal influences, especially in young adult females
• Genetic predisposition in individuals with darker skin

Though these factors are associated with PMH, the exact cause is not definitively known. Environmental and lifestyle factors may also influence the appearance of symptoms.

Progressive Macular Hypomelanosis Diagnosis

Diagnosis of PMH is primarily clinical, based on the appearance and distribution of the skin lesions. A dermatologist examines the skin under natural and UV light (Wood’s lamp) to rule out other conditions like vitiligo or fungal infections.

Additional diagnostic methods may include skin biopsy and microbiological tests to detect bacterial presence. However, these are rarely needed unless the diagnosis is uncertain. Identifying PMH correctly is essential to avoid unnecessary treatments and anxiety.

Progressive Macular Hypomelanosis Treatment

Treatment for PMH focuses on repigmentation and reducing bacterial colonization. A common approach includes a combination of topical antibiotics such as clindamycin and benzoyl peroxide to target Cutibacterium acnes.

In some cases, narrowband UVB phototherapy is recommended to stimulate melanin production. Consistency in treatment is crucial for visible results. While PMH is not harmful, treatment is pursued mainly for cosmetic reasons.

Progressive Macular Hypomelanosis vs Vitiligo

PMH is often confused with vitiligo due to the appearance of light patches on the skin. However, key differences exist between the two conditions:

• PMH patches are less sharply defined compared to the clear, well-demarcated patches of vitiligo
• Vitiligo affects any body part, including face and limbs, while PMH is usually confined to the trunk
• Vitiligo involves complete loss of pigment, while PMH shows partial hypopigmentation
• PMH may show bacterial colonization, while vitiligo is autoimmune in nature

Accurate diagnosis by a dermatologist is important to differentiate the two, as their treatments and progression are significantly different.