Definition
Milia en plaque (MEP) is a rare dermatological disorder characterized by numerous milia—small, keratin-filled epidermoid cysts—arranged in a confluent, plaque‑like pattern, often accompanied by an erythematous or papular background.
Overview
First described in the early 20th century, milia en plaque predominantly affects middle‑aged adults and shows a slight female predominance. Lesions most commonly appear on the periauricular region, face, and neck, but can involve other skin areas. The condition is considered a distinct clinical variant of primary milia rather than a manifestation of an underlying systemic disease, although associations with chronic inflammatory dermatoses (e.g., rosacea, sebaceous hyperplasia) have been reported. Treatment is usually cosmetic, aiming to reduce the visible cysts; options include topical retinoids, manual extraction, laser therapy, and surgical excision. Recurrence is common, and the disease course is typically chronic but benign.
Etymology/Origin
The term combines the Latin milium (plural of milium), meaning “small grain” or “millet,” referring to the tiny, millet‑seed‑like appearance of the cysts, with the French preposition en (“in”) and the English word plaque, denoting a flat, raised area of skin. The phrase “milia en plaque” was first employed in dermatological literature to describe the plaque‑type aggregation of milia.
Characteristics
- Morphology: Numerous 1–2 mm, white‑to‑yellow, dome‑shaped papules (milial cysts) coalescing into a larger, often erythematous plaque.
- Distribution: Predilection for the periauricular area, cheeks, forehead, and neck; can be unilateral or bilateral.
- Histopathology: Presence of multiple epidermal inclusion cysts within the superficial dermis, lined by stratified squamous epithelium containing lamellated keratin. The surrounding dermis may show mild inflammatory infiltrate.
- Differential Diagnosis: Includes syringoma, sebaceous hyperplasia, basal cell carcinoma (nodular type), and other papular eruptions such as papular elastorrhexis.
- Management: Physical extraction of individual milia, topical keratolytics (e.g., tretinoin), chemical peels, laser modalities (CO₂, Er:YAG), cryotherapy, or surgical excision for refractory plaques.
Related Topics
- Milia (primary and secondary): Small epidermoid cysts that can occur spontaneously or secondary to skin trauma, prolonged corticosteroid use, or other dermatoses.
- Milium (plural milia): The Latin term for the cystic lesions themselves.
- Cutaneous cysts: A broader category encompassing various benign skin cysts such as epidermoid cysts, sebaceous cysts, and trichilemmal cysts.
- Dermatologic laser therapies: Techniques frequently employed in the treatment of cosmetic skin conditions, including milia en plaque.
- Rosacea: A chronic inflammatory facial dermatosis that can coexist with or predispose to milia formation.