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On-line version ISSN 1806-4841
An. Bras. Dermatol. vol.85 no.1 Rio de Janeiro Jan./Feb. 2010
IMAGING IN DERMATOLOGY
Débora Cadore de FariasI; Antonella TostiII; Nilton Di ChiacchioIII; Sergio Henrique HirataIV
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
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.
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.
1. Rezze GG, Soares de Sá BC, Neves RI. Dermatoscopia: o método de análise de padrões. An Bras Dermatol. 2006;81:261-8. [ Links ]
2. Tosti A, Piraccini BM, Farias DC. Dealing with melanonychia. Seminars in Cutaneous Medicine and Surgery. 2009;28:49-54. [ Links ]
3. Tosti A, Pirraccini BM, Farias DC. Nail dermoscopy. In: Micali G. Videodermatoscopy in Clinical Pratice. London: Informa Healthcare; 2009. [ Links ]
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. [ Links ]
5. Ohtsuka T, Yamakage A, Miyachi Y. Statistical definition of nailfold capillary pattern in patients with psoriasis. Int J Dermatol. 1994;33:779-82. [ Links ]
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. [ Links ]
7. Bhushan M, Moore T, Herrick AL, Griffiths CEM. Nailfold video capillaroscopy in psoriasis. Br J Dermatol. 2000;142:1171-6. [ Links ]
Mailing Address: Recebido
em 02.07.2009. *
Study conducted at the Dermatology Clinic, São Paulo State Hospital for
Civil Servants, São Paulo, SP, Brazil
Débora Cadore de Farias
Rua João Moura, 975 - ap. 164 - Jardim América
05412 002 São Paulo, SP
Aprovado pelo Conselho Consultivo e aceito para publicação em 18.12.09.
Financial support: None
Conflict of interest: None
* Study conducted at the Dermatology Clinic, São Paulo State Hospital for Civil Servants, São Paulo, SP, Brazil