Nail involvement is an extremely common feature of psoriasis and affects approximately 10-78 of psoriasis patients with 5-10 of patients having isolated nail psoriasis. A punch or an excision biopsy can be applied to any individual anatomical part of the nail unit, like the nail bed, nail plate, nail fold, or matrix, whereas with a longitudinal nail biopsy, a part of all the parts of the nail unit are biopsied. Histopathology of nail psoriasis varies according to the clinical focus of the disease. Therefore, psoriatic nail disease may have a different contribution from innate immunity and adaptive immunity compared with skin-limited disease 15,16. A biopsy of the nail unit is not necessary in most cases. Several different nail disorders were discovered or confirmed by nail biopsy. The list may include psoriasis, lichen planus, twenty nail syndrome, lichen sclerosis et atrophicus, eczema, Darier s disease and also tumors like melanocytic nevi, Bowen’s disease, melanoma, and others. The type of nail biopsy depends largely on the location of the pathology in the nail unit 15. Nail bed cells do not have any independent movement, and it is yet to be clearly demonstrated whether they are incorporated into an overlying nail plate as it grows distally.
(From De Berker D et al: Keratin expression in the normal nail unit: Markers of regional differentiation. The presence of Merkel cells in the nail matrix has been demonstrated. In this article, the authors will review the most common nail disorders in the differential diagnosis of fungal infection (onychomycosis) and cutaneous clues to systemic disease. Clinically, the most common nail disorders can be classified into 5 groups based on the most salient presenting features: nail discoloration, nail thickening, nail surface abnormalities, inflammation of the nail fold, and nail fungal infection. Psoriatic nails may also have an adjacent proximal, yellow-brown, regular band of discoloration of the nailbed (oil on water sign) not seen with tinea. Fungal infection of the nails and skin can represent a disruption of the cutaneous barrier that leads to secondary bacterial infection in chronic wounds. This new focus has shown extraordinary promise for long term medical management, particularly in severe cases. The epidemiological features of palmoplantar (acral) psoriasis has remained somewhat obscure; however, in our experience, neither palmoplantar pustulosis nor the chronic plaque form of acral psoriasis can be considered rare in a podiatric practice, and both are certainly under-diagnosed. In the lower extremity, keratinizing nail unit dystrophy (resembling onychomycosis) (Figure 1).
The assessment of disease activity in PsA should therefore evaluate each of these clinical domains carefully. Responsiveness or sensitivity to change tests how well the scores on the instrument change to reflect changes in the criterion measure. Most clinical studies have reported the frequency of enthesitis in PsA cohorts in the 30 50 range 21, 22, but this may be an underestimate, as now imaging studies such as ultrasonography or magnetic resonance imaging (MRI) have demonstrated enthesopathy not appreciated clinically. Nail involvement is common in patients with psoriasis and PsA and can be severe and disfiguring. Nail diseases can lead to impairment of hand function, difficulty in walking, and cosmetic disfigurement. Nail unit tumors have atypical presentations as the lesion in nail matrix present with secondary nail plate changes and nail bed tumors are obscured by the nail plate. OCT works in analogy to USG; the infrared light reflected from the skin is measured and the intensity is imaged as a function of position. 25 recently reported OCT to provide higher resolution changes compared with nail USG in nail psoriasis. Changes in the appearance of the nail apparatus can be produced by a variety of conditions. Reflection of the proximal nail fold revealed projections arising from the nail matrix. The clinical differential diagnosis of onycho-matricoma is extensive,7,8 but onychomatricoma has characteristic clinical and histopathologic features that allow its separation from other nail disorders and subungual tumors (Table).
OBJECTIVE: The purpose of this study was to define the clinical and epidemiologic features of this disease in Spain and to compare patients with psoriasis of early and late onset. Guttate psoriasis, nail involvement, evidence of precipitating factors, and a recurrent clinical course were more frequent in this group of patients. The prevalence of psoriasis in African Americans has been previously reported as rare. Dennis McGonagle, Academic Unit of Muscoskeletal Disease, Chapel Allerton Hospital, Chapeltown Road, Leeds LS7 4SA, UK. The relationship between nail disease and psoriatic arthritis (PsA) of the distal interphalangeal (DIP) joint is well-recognized 1 4, although the basis for this association is poorly understood.