Autoimmune · Trichoscopy · CityLink Mall
A smooth, sharply defined bald patch appearing over weeks is not pattern hair loss and does not respond to anything that treats pattern hair loss. Alopecia areata is an autoimmune condition in which the immune system attacks the growing hair follicle — the follicle survives, which is why regrowth remains possible, and why the diagnosis has to be made correctly.
The lower portion of a growing hair follicle is one of a small number of sites in the body that the immune system is normally instructed to ignore. This state, called immune privilege, is maintained by local signalling that suppresses antigen presentation around the anagen bulb. It exists because the growing follicle expresses proteins the immune system would otherwise treat as foreign. When that privilege collapses — and the trigger is frequently never identified — those proteins become visible to circulating lymphocytes for the first time.
What follows is a focal attack. CD8-positive T lymphocytes infiltrate around the bulb, producing the dense peribulbar inflammation that pathologists describe as a swarm of bees. The follicle responds by abruptly terminating anagen and dumping the hair. Because a patch of follicles is affected together and they are broadly in phase, an entire circular area is released within a short period, which is why the onset is rapid and the edge of the patch is sharp rather than graded.
Critically, the attack targets the growing hair rather than the follicle's stem cell reservoir, which sits higher up in the bulge region and is not destroyed. This is what makes alopecia areata a non-scarring alopecia, and it is the reason a patch that has been bare for months can refill completely. The follicle has not been removed; it has been forced into dormancy. Regrowth, when it comes, frequently emerges as fine white or depigmented hair which repigments over subsequent cycles.
Trichoscopy at the edge of an active patch shows features that are close to diagnostic. Exclamation-mark hairs — short broken shafts that taper toward the scalp rather than away from it — indicate the follicle was damaged mid-growth. Yellow dots represent keratinous debris in empty follicular openings and black dots represent hairs fractured at the surface. Their presence, together with a smooth patch and no scale or scarring, separates this from every other cause of localised loss.
Patterns
Alopecia areata is described by how much scalp and body hair the immune attack has involved, and the extent matters because prognosis and appropriate care differ sharply between them. Limited patchy disease and extensive disease are the same pathology behaving very differently, and the second belongs under dermatological supervision.
A round, smooth, sharply edged patch is not balding. It is an immune event, and treating it as balding delays the only thing that helps.
The Decision
The first job is to establish that this is alopecia areata and not something that resembles it. Tinea capitis produces patchy loss with scale and broken hairs and is a fungal infection requiring oral antifungal treatment. Early traction alopecia produces marginal loss that can mimic ophiasis. Trichotillomania produces irregular patches with hairs of varying lengths rather than a uniformly smooth surface. Discoid lupus and lichen planopilaris produce patches that are scarred, and those do not regrow. A smooth patch with no scale, no scarring and exclamation-mark hairs at the margin is a different problem from all of them.
The second job is to be clear about where care belongs. Limited patchy disease in an adult is often managed conservatively, and intralesional corticosteroid to a small number of patches is an established approach. Rapidly progressive loss, involvement of a large proportion of the scalp, ophiasic distribution, loss of eyebrows or eyelashes, nail involvement, or any presentation in a child should go to a dermatologist. The systemic and immunomodulatory options relevant to extensive disease — including the newer targeted agents — are prescribed and monitored in that setting, and an aesthetic practice is not the right place for them.
What an aesthetic consultation does contribute is accurate diagnosis, honest framing, and management of what else is happening to the scalp at the same time. Alopecia areata frequently coexists with androgenetic miniaturisation or with an unrelated telogen effluvium, and untangling the components changes what anyone should expect. It is also worth saying plainly that the course is unpredictable: patches refill, recur, and refill again, and no one can promise which.
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