Dermoscopy in nail psoriasis

Abstracts

Os autores relatam sua experiência no uso da dermatoscopia na psoríase ungueal e descrevem os achados dessa ferramenta diagnóstica.

Doenças da unha; Psoríase; Psoríase

IMAGING IN DERMATOLOGY

^IDermatologist, Dermatology Clinic, Santa Casa de São Paulo, São Paulo, SP, Brazil

^IIProfessor and Head of the Department of Dermatology, University of Bologna, Italy

^IIIAssistant Physician, Dermatology Clinic, São Paulo State Hospital for Civil Servants, São Paulo, SP, Brazil

^IVDoutor em medicina pela Universidade Federal de São Paulo (Unifesp), médico do departamento de dermatologia da Universidade Federal de São Paulo(Unifesp), ABC – São Paulo (SP), Brasil

Mailing Address

ABSTRACT

The authors report on their experience with the use of dermoscopy in nail psoriasis and describe their findings with this diagnostic tool.

Keywords: Nail diseases; Psoriasis; Psoriasis/diagnosis.

INTRODUCTION

Dermoscopy is a procedure widely used to aid diagnosis of melanocytic or non-melanocytic skin lesions.¹ In the nail, use of this tool in melanocytic lesions has already been substantiated ²; however, it has only recently begun to be used in non-melanocytic lesions of the nail, where it appears to be of great diagnostic value. Nevertheless, insufficient studies have been performed to this date to validate its use, much less to recommend it as a substitute for nail biopsy.

Dermoscopic findings in nail psoriasis depend on the portion of the nail that is affected by the disease.³ In the matrix of the nail, psoriasis produces abnormalities on the surface of the nail plate such as pitting. When psoriasis affects the nail bed, it may produce onycholysis, salmon patches, hemorrhages and subungual hyperkeratosis. Dermoscopy permits better visualization of abnormalities in the nail plate and bed, and aids detection of the vascular abnormalities in the hyponychium and proximal nail fold that are indicative of disease.

To perform dermoscopy of the nail plate in cases of psoriasis, magnification of at least 30x is required. Polarized or non-polarized light devices may be used. When non-polarized light is used, it is preferable to use a transparent gel as the interface, since this fills the space between the convex surfaces of the nail plate and the plane of the dermoscopic lens. The findings of dermoscopy of the nail plate in nail psoriasis are described in Table 1.

When onycholysis is present, dermoscopy generally shows an erythematous border, often subclinical and invisible to the naked eye, represented by a reddish-orange stain surrounding the area of onycholysis. This finding is specific to onycholysis in nail psoriasis (Figura 1A).

Splinter hemorrhages are the result of bleeding in the capillaries of the nail bed. They are shown as marks that run longitudinally in the direction of nail growth, and are caused by the successive incorporation of blood in the ventral nail plate. This finding is not specific to psoriasis. These hemorrhages are also found in onychomycoses, contact dermatitis and nail trauma (Figura 1A).

To perform dermoscopy of the hyponychium, polarized or non-polarized light devices may also be used. Findings include dilated, irregularly distributed, long and tortuous capillaries (Figura 1B). Magnification of at least 40x is required to visualize abnormal capillaries. In 2008, Iorizzo et al. showed that capillary density is positively correlated with the severity of the condition. This study also showed that quantitative analysis of the capillaries correlates with response to treatment. In this study, following three months of topical treatment with calcipotriol, a reduction in the number of capillaries was found in the patients.⁴

In the authors' experience, dermoscopy of the hyponychium is the best diagnostic tool for confirming a diagnosis of psoriasis in patients with onycholysis alone or mild hyperkeratosis of the nail bed.³

Dermoscopy of the proximal nail fold is also useful for evaluating the severity of the disease, this site being appropriate for identifying quantitative and morphological abnormalities of the capillaries. The number and diameter of the capillaries are found to be significantly reduced in cases of psoriasis.^5-7

In 1982, Zaric et al. reported a reduction in the size of the capillaries of the proximal nail fold in patients with skin psoriasis and psoriatic arthritis compared to a control group.

In 2000, Bhusham et al. found a reduction in capillary density in the proximal nail fold of patients with nail psoriasis or psoriasis with nail and joint involvement compared to a control group. Only in patients with psoriatic arthritis, irrespective of whether or not this was associated with nail involvement, was a reduction also found in the diameter of these capillaries.

In conclusion, dermoscopy is a noninvasive, quickly applied and inexpensive test that may aid diagnosis of nail psoriasis in inconclusive cases and improve the follow-up of the patient with respect to his/her response to treatment.

REFERENCES

• 1. Rezze GG, Soares de Sá BC, Neves RI. Dermatoscopia: o método de análise de padrões. An Bras Dermatol. 2006;81:261-8.
• 2. Tosti A, Piraccini BM, Farias DC. Dealing with melanonychia. Seminars in Cutaneous Medicine and Surgery. 2009;28:49-54.
• 3. Tosti A, Pirraccini BM, Farias DC. Nail dermoscopy. In: Micali G. Videodermatoscopy in Clinical Pratice. London: Informa Healthcare; 2009.
• 4. Iorizzo M, Dahdah M, Vicenzi C, Tosti A. Videodermoscopy of the hyponychium in nail bed psoriasis. J Am Acad Dermatol. 2008;58:714-5.
• 5. Ohtsuka T, Yamakage A, Miyachi Y. Statistical definition of nailfold capillary pattern in patients with psoriasis. Int J Dermatol. 1994;33:779-82.
• 6. Zaric D, Clemmensen OJ, Worm AM, Stahl D. Capillary microscopy of the nail fold in patients with psoriasis and psoriatic arthritis. Dermatologica. 1982;164:10-4.
• 7. Bhushan M, Moore T, Herrick AL, Griffiths CEM. Nailfold video capillaroscopy in psoriasis. Br J Dermatol. 2000;142:1171-6.

Dermoscopy in nail psoriasis

Débora Cadore de Farias^I; Antonella Tosti^II; Nilton Di Chiacchio^III; Sergio Henrique Hirata^IV

Publication Dates

• Publication in this collection
  06 May 2010
• Date of issue
  Feb 2010

History

• Accepted
  18 Dec 2009
• Received
  02 July 2009