Nail alopecia areata

Introduction

Alopecia areata (AA) is an immune mediated disease presenting with non-cicatricial alopecia occurring in a circumscribed or generalized pattern. Nail abnormalities are present in ~20% of adults and 50% of children with alopecia areata and is most common in male patients with severe involvement. Incidence is much lower in patients with focal AA (AAF) than in patients with severe forms of AA like alopecia totalis (AAT) and universalis (AAU). Nail involvement in AA may precede, accompany or follow development of alopecia patches. Thus the presence of nail changes in AA can be considered an indicator of severity of the disease and probably reflects a more refractory disease as compared to patients with absence of nail changes.

 

Pathogenesis

 

The patho-genic mechanism of nail changes in AA is unknown, but it has been proposed that because the nails are similar in structure and growth to hair follicles, they are affected by the same inflammatory reaction that targets hair follicles in AA. Histopathological observations using light and electron microscopic techniques show that most of the nail changes in AA are found within the proximal matrix, and are less pronounced in the distal matrix, and negligible in the nail bed.

 

Clinical features

 

Signs that are characteristic of nail alopecia areata include geometric pitting and trachyonychia.

Geometric pitting is most typical. Pits are small, superficial, and regularly distributed in a geometric pattern (grid-like) along longitudinal and transverse lines, giving the nail a “hammered brass” appearance. Pits in psoriasis are a bit larger, deeper and irregularly distributed.

Trachyonychia is quite common in children than adults (12% of children and 3% of adults with severe alopecia areata) and most frequently seen in patients with alopecia totalis or universalis. In trachyonychia, there is nail plate roughness primarily due to excessive longitudinal ridging. Several nails are usually affected and in some patients, all the nails are dystrophic. The nails are thin, opaque and lusterless and give the impression of having been sandpapered in a longitudinal direction, i.e. vertically striated. The cuticles are often hyperkeratotic. Trachyonychia is fairly asymptomatic and patients or their parents primarily complain of brittleness and the cosmetic appearance. In addition to alopecia areata, trachyonychia is occasionally caused by several inflammatory diseases that mildly disturb nail matrix keratinization, including lichen planus, eczema, and psoriasis. Determination of the underlying inflammatory disease responsible for the trachyonychia requires a nail biopsy. However, this is generally not recommended because of the benign nature of the disease and the tendency for the majority of patients to spontaneously improve.

Additional nail abnormalities observed in alopecia areata include punctate leukonychia, mottled erythema of lunulae (red lunula), and onychomadesis.

Red spots on the lunula are less frequent, but very specific for severe AA. Patients with AAU have a significantly higher risk of developing red spots on the lunula than patients with AAT and AAF.

 

Clinical course, prognosis and treatment

Occurring more commonly in severe AA, the nail changes usually run a protracted course over years. Successful systemic treatments will greatly improve the nails. Tofacitinib is a Janus kinase inhibitor with a good effect on hair loss and nail AA. A case report showing that Tofacitinib (5 mg twice daily) for 10 months results in remarkable improvements of not only hair regrowth but also nail changes in Alopecia universalis.

 

The prognosis of nail AA is linked to that of AA in general. The nail changes may persist for a long period of time even after treatment and complete hair regrowth. Permanent nail dystrophy after resolution of the AA is not observed.