10.3 Acne, Vascular Lesions, Birthmarks & Hair-Nail Disorders

Acne, vascular lesions, birthmarks, and hair-nail disorders are the other half of dermatology volume: teens in the exam room, infants in the 2-month slot, and the maltreatment differential that sits on a blue-gray lumbosacral patch. Domain II is classification (comedonal versus nodulocystic; hemangioma versus port-wine; six café-au-lait macules; patchy alopecia with scale versus without). Domain III is a stepwise acne plan, knowing which hemangiomas get a beta-blocker referral, and documenting congenital dermal melanocytosis so the next examiner never calls it yesterday's bruise.

Clinic opening. A 10-week-old has a bright red plaque enlarging on the upper eyelid. The caregiver was told strawberry marks go away. If you watch a periocular hemangioma through the rapid-growth window and the child develops astigmatism, you missed the referral rule.

Acne: match the type to the ladder

Acne vulgaris is a pilosebaceous disorder of adolescents (and some infants). Classify before you prescribe.

BP is antibacterial and reduces resistance; it bleaches towels and pillowcases. Topical retinoids are comedolytic and are the maintenance backbone — counsel irritation, nightly use on dry skin, and sunscreen. Combined oral contraceptives and spironolactone are adjuncts for some adolescent females (pregnancy counseling, blood pressure, and labeling). Do not use oral antibiotics as monotherapy or indefinitely. Do not start isotretinoin in unsupervised primary care: iPLEDGE, teratogenicity, laboratory monitoring, and mood/skin counseling belong with dermatology.

Clinic vignette. A 16-year-old has nodules along the jaw and pitted scars. He already used adapalene, BP, and two 3-month doxycycline courses with BP. Next step is isotretinoin referral, not a third oral antibiotic as monotherapy.

Infantile acne (true comedones in a baby) is not neonatal cephalic pustulosis. Mild cases can be watched or treated with topical agents; nodular infantile acne is referral.

Infantile hemangioma: most watch, some cannot wait

Infantile hemangiomas (IH) are the common strawberry vascular tumors. They are often absent or faint at birth, proliferate in the first 3–5 months, then involute over years. The AAP 2019 IH clinical practice guideline is the referral spine: most small, uncomplicated, non-critical lesions are observed.

Refer promptly (pediatric dermatology or a vascular-anomalies program) for oral beta-blocker (propranolol) evaluation — and sometimes imaging — when the lesion is:

• Periocular (vision, astigmatism, amblyopia)
• Ulcerating (pain, bleeding, infection — lips, diaper, skinfolds)
• Beard distribution (lower lip, chin, neck — airway hemangioma risk)
• Segmental facial — PHACE association (Posterior fossa, Hemangioma, Arterial lesions, Cardiac, Eye)
• Large segmental lesions elsewhere, hepatic (high-output failure, hypothyroidism), or lumbosacral (spinal dysraphism; PELVIS/LUMBAR spectrum)

Topical timolol is sometimes used for small, thin, superficial IH. It is not a substitute for systemic therapy when the site is high-risk. The trap is reassurance through months 2–4 when growth is steepest. Propranolol is not a casual primary-care start; screening for cardiac, glucose, and PHACE contraindications lives with the treating team.

Port-wine versus salmon patch

Salmon patch (nevus simplex, stork bite or angel kiss) is a faint pink macule on the glabella, eyelids, or nape. It blanches. It typically fades (the nape may linger). No workup.

Port-wine stain (capillary malformation, nevus flammeus) is present at birth, darker, does not fade, and grows with the child. Facial PWS in a V1/forehead distribution raises Sturge-Weber concern (glaucoma, leptomeningeal involvement). That child needs ophthalmology and often neurology/dermatology, not it will lighten by kindergarten. Laser is specialty care.

Café-au-lait macules and NF1

A few café-au-lait macules (CALMs) are common. Six or more CALMs of ≥5 mm in a prepubertal child (or ≥15 mm after puberty) is a diagnostic criterion for neurofibromatosis type 1 when combined with other features (axillary or inguinal freckling, neurofibromas, optic pathway glioma, Lisch nodules, osseous lesions, an affected first-degree relative). In primary care: count them, measure them, look for freckling, plot growth and head circumference, and refer to genetics or neurology when the count or associated findings raise NF1. Do not wait for a plexiform neurofibroma to appear before you count.

Mongolian spots versus bruise

Congenital dermal melanocytosis (Mongolian spot) is blue-gray, often lumbosacral or on the buttocks, common in children with darker skin phototypes, present from birth, with indistinct borders. It does not evolve through red-blue-green-yellow bruise colors. Document location, size, and color in the newborn or early well-child record.

A bruise is tender, has edges that change over days, and appears in patterns that may match injury. Unexplained bruises in non-cruising infants, patterned marks, and bruises on ears, neck, or torso are maltreatment red flags (chapter 20). Congenital dermal melanocytosis is not a bruise — but you still document so the next examiner does not file a report from ignorance, and you still report when the lesion history and exam do not match a birthmark.

Clinic vignette. A 4-month-old has a uniform blue-gray sacral patch the size of a palm. Parents say it has been there since birth. The same chart has no other injuries. Document the birthmark. A new tender purple mark on the pinna is a different conversation.

Alopecia: areata versus tinea versus trichotillomania

Never treat presumed areata with oral antifungal just in case if the scalp is smooth and KOH or culture is negative. Never miss a kerion because you liked the areata story.

Nails: biting versus fungus

Nail biting and trauma cause irregular free edges, habit-tic ridging, and sometimes paronychia. Onychomycosis is uncommon in young children: a thickened, yellow, crumbly nail, often with tinea pedis. Confirm with KOH or culture before a long oral antifungal course. Psoriasis makes pitting and oil-drop changes. Ingrown toenails: shoes, trimming, soaks; infection when indicated. Do not put every dystrophic pediatric nail on adult-duration terbinafine without a confirmed dermatophyte.

Exam traps

Watch-and-wait a periocular, ulcerating, beard, or segmental hemangioma. Count five CALMs and stop thinking. Call a port-wine stain a salmon patch. Start isotretinoin yourself or, the opposite error, leave scarring acne on doxycycline forever. Give oral antibiotic acne therapy without BP. Treat trichotillomania as tinea. Fail to document dermal melanocytosis — or fail to report a bruise you hoped was a birthmark.

Clinic close. Comedones: retinoid plus BP. Inflammatory: BP plus retinoid; oral antibiotic only with BP and a stop date. Scars and nodules: isotretinoin referral. Most hemangiomas: watch. Eyelid, ulcer, beard, PHACE-risk segmental: beta-blocker pathway now. Salmon patch fades; port-wine does not. Six CALMs: NF1 workup. Blue-gray from birth: document. Smooth bald patch: areata. Scaly bald patch with nodes: oral tinea treatment. Irregular broken hairs: habit. Ugly nail in a biter: usually not fungus.