Milium
A milium (plural: milia) is a small, benign microcyst, usually 1–2 mm across, located in the superficial papillary dermis just beneath the epidermis. Each milium is a tiny cyst lined by fully keratinizing stratified squamous epithelium and filled with tightly packed, concentrically layered keratin.
Unlike whiteheads (closed comedones), which form when sebum and the bacterium C. acnes block a pore, milia contain no sebum and have nothing to do with the oil glands. They are simply a buildup of keratin from keratinocytes that cannot escape to the skin surface.
Where Milia Come From and Why Keratin Builds Up
- Primary milia:
- Newborns: Seen in about 50% of newborns because the openings of the vellus hair follicles are not yet fully mature, so keratin gets trapped and forms shallow microcysts.
- Adults: Usually arise spontaneously from the vellus hair follicle opening or from the epidermal portion of a sweat duct. Shed keratin rolls up in tight, onion-like layers, forming a firm white-yellow bead under the skin.
- Secondary (traumatic) milia:
- After injury or blistering disease: They develop after mechanical injury, burns, deep resurfacing with ablative fractional laser, dermabrasion, or subepidermal blistering diseases such as epidermolysis bullosa, porphyria cutanea tarda and pemphigoid.
- Duct entrapment: When the epidermis and the sweat ducts or hair follicles are damaged and then heal, re-epithelialization can cut off or partly seal the end of an eccrine duct or follicle, turning it into a closed pocket where keratin accumulates.
Why Milia Can't Be Squeezed Like Ordinary Pimples
The wall of a milium is very thin, but it is a complete epithelial lining anchored in the papillary dermis, and the keratin inside is dense, tough and dry. Unlike blackheads or whiteheads, a milium has no natural opening to the skin surface. Squeezing it therefore can't push the keratin out; it only crushes the surrounding dermis, causing bruising, inflammation and pitted scars.
At Haute-Derma, our approach to milia rests on three principles: minimal, pinpoint intervention, complete removal of the cyst wall, and no scarring or dark marks around the eyes. Because milia so often appear on the thin, delicate skin of the eyelids, accurate diagnosis with dermoscopy is essential to tell them apart from syringoma and xanthelasma. We rely on two main techniques: microsurgical opening with a sterile needle or micro-punch for individual milia, and ultra-short-pulse 2940 nm Er:YAG laser to precisely vaporize the overlying epidermis in areas with many milia. Both remove the keratin core gently without harming healthy tissue.
Histopathology and Diagnostic Dermoscopy and Ultrasound Findings
Characteristic Features Under the Microscope
Histologically, a milium looks like a miniature epidermoid cyst sitting at a more superficial level:
- Location: In the superficial papillary dermis, directly beneath the epidermis.
- Cyst wall: A thin stratified squamous epithelium (1–3 cell layers) with a distinct granular layer (stratum granulosum).
- Cyst contents: Tightly packed, concentrically laminated keratin. There is no surrounding inflammation unless the lesion has been squeezed or manipulated.
Dermoscopy and High-Frequency Skin Ultrasound Criteria
Imaging at Haute-Derma helps assess how deep the lesion is and what it is:
- Dermoscopy:
- Homogeneous off-white to yellowish round structure: The opaque look of dense keratin beneath a thin, translucent epidermis.
- No central pore and no vessels: The overlying epidermis is completely smooth, with no increased vascularity within the lesion.
- Opal-like sheen: The lesion looks like a tiny pearl sitting just under the skin.
- High-frequency skin ultrasound (20–50 MHz):
- Superficial hypoechoic microcyst: A small 1–2 mm structure confined to the superficial dermis.
- Hyperechoic central core: Reflects the dense keratin in the center of the cyst.
Clinical Features
- Primary lesion: Round, firm, microcystic papules 1–2 mm across, opaque white or pale yellow.
- Typical sites: Around the eyes (upper and lower eyelids, temples), cheeks, nose and forehead.
- Behavior: Completely painless and non-itchy. In adults they do not go away on their own, whereas in newborns they usually clear within a few weeks.
Clinical and Histological Differential Diagnosis
| Milium | Syringoma | Xanthelasma |
|---|---|---|
| Superficial keratin microcyst | Benign sweat duct tumor | Lipid deposits / foamy macrophages |
| Firm, opaque white/yellow | Soft to firm, skin-colored or pink | Soft, flat, chalky yellow |
| Hard, dry, round keratin bead | Solid tissue, no core | Flat fatty plaque |
| Squamous epithelium lining a keratin-filled microcyst | "Tadpole"-shaped ducts in the dermis | Lipid-laden foamy histiocytes |
| Well-defined opaque white round structure | Homogeneous skin-colored area with linear vessels | Yellow cloud-like structureless areas |
Microsurgical Extraction, Er:YAG Laser and Skin Recovery at Haute-Derma
At Haute-Derma, milia treatment aims for complete removal with the best possible cosmetic result for the sensitive skin around the eyes:
Micro-Lancet Extraction (for Individual Milia)
- Tiny epidermal nick: The doctor uses a sterile 30G needle or a very fine beveled tip to make a nick about 0.5 mm long in the thin skin covering the milium.
- Enucleation of core and cyst wall: Using a fine extraction instrument, the doctor presses gently at the base and lifts out the hard, round keratin bead together with its epithelial wall. If the wall is not fully removed, the milium can come back.
2940 nm Er:YAG Laser Micro-Vaporization (for Clustered or Periocular Milia)
- Ultra-fine vaporization of the overlying skin: The 2940 nm Er:YAG laser, used with micro-short pulses, is absorbed by water about 10 times more strongly than a CO2 laser. It vaporizes only the 10–20 µm of epidermis covering the milium, with no heat spread or burns to the surrounding tissue.
- Releasing the keratin core: Through the tiny laser opening, the keratin bead slides out easily with light, targeted pressure.
Skin Recovery and Prevention of Dark Marks and Scars Around the Eyes
- Pincer Biomodulation, exclusive to Haute-Derma: A molecular biotechnology treatment applied to the treated skin helps the tiny openings heal within 24–48 hours.
- 590 nm yellow LED light therapy: Calms mild redness and minimizes the risk of post-inflammatory hyperpigmentation (PIH), which matters especially on eyelid skin.
