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Vol. 10. Issue 4.
Pages 260-261 (July - August 2014)
Vol. 10. Issue 4.
Pages 260-261 (July - August 2014)
Images in Clinical Rheumatology
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Arthritis and Onychophagia: A Confounding Factor
Artritis y onicofagia: un factor de confusión
Lucía Pantoja Zarzaa,��
Corresponding author

Corresponding author.
, Carolina Díez Morrondoa, José Antonio Manjón Hacesb
a Unidad de Reumatología, Hospital El Bierzo, Ponferrada, León, Spain
b Servicio de Dermatología, Hospital El Bierzo, Ponferrada, León, Spain
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Table 1. Differential Diagnosis Between the 4 most Common Diseases of the Nails.
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The diagnosis of nail deformities may not be simple. Even with nail psoriasis being one of the most common onychodystrophies, it is important to recognize other common causes, such as nail biting, self-induced or traumatic causes.1

Clinical Case

The patient is a 48-year-old woman, smoker of 20 packs/year, with a family history of psoriasis (mother and brother). She had carpal arthritis which had lasted for 9 months, with no history of inflammatory back pain, along with major onychodystrophy of the hands and a normal skin examination (Fig. 1). Analytical studies were normal or negative, including acute phase reactants, rheumatoid factor, anti-CCP and antinuclear antibodies and HLAB27. Radiographs of hands and pelvis showed no abnormalities. Treatment was started with methotrexate and a dermatologist was consulted for suspected psoriasis with nail involvement in psoriatic arthropathy. The diagnosis was “traumatic dystrophy due to onychophagia”. The patient stopped biting her nail for 6 months (Fig. 2). The response to methotrexate has been good and she has not presented arthritis. After 4 years of follow-up, the case remains an undifferentiated arthritis, with negative CASPAR criteria for psoriatic arthropathy.

Fig. 1.

Nail disorders by onychophagia: absence of the distal end of the nail, subungual ecchymosis, callus type mechanical injury, deformity of the paronychium and characteristic grooves in the nail, indicative of chronic trauma of the nail bed.

Fig. 2.

Fingernails with no alterations after 6 months.


In all, 12% of patients with psoriasis have nail involvement, although the reported prevalence varies, being greater if there is joint involvement.2 The manifestations of nail psoriasis are multiple.3 The most common form is subungual hyperkeratosis, and nail pitting is the characteristic sign, although not pathognomonic, but oil spots under the nail bed can be considered very specific.4 It may be clinically indistinguishable from onychomycosis and differential diagnosis must also be made with other processes, including self-induced nail dystrophy (Table 1).

Table 1.

Differential Diagnosis Between the 4 most Common Diseases of the Nails.

  Color  Onycholysis  Punctuate depressions  Transverse grooves 
Fungal infections  Often yellow or brown: part of the nail or the entire nail  Frequent  Rare  Missing 
Psoriasis  Normal or yellow or brown  Frequent  Presents and fine  Rare 
Chronic paronychia  Black or brown discoloration of the edge of the nail  Usually absent  Uncommon  Frequently 
Onychophagia  Normal with subungual hemorrhages  On the tip  Missing  Present 

Onychophagia can be explained as a compulsive habit that causes the destruction of the nails. It is a common behavior among children and young adults, although underestimated, which has received little attention in the psychiatric and dermatologic literature, but can be related to obsessive-compulsive disorders.5 Complications include superinfection, paronychia and dental problems, and phalanx osteomyelitis may occur exceptionally.6 Most patients admit onychophagia, so in nail deformities it should be one of the first direct questions we ask to exclude the diagnosis.

In our patient, because of the arthropathy, it was very important to diagnose the cause of onychopathy. If the source had been psoriasis, she would have been diagnosed with psoriatic arthropathy based on the CASPAR7 criteria. However, we showed that with willpower she could stop nail-biting for 6 months. This confirms once again the importance of the history and multidisciplinary collaboration.

Ethical ResponsibilitiesProtection of people and animals

The authors declare that no experiments have been performed on humans or animals.

Data confidentiality

The authors declare that they have followed the protocols of their workplace regarding the publication of data from patients and that all patients included in the study have received sufficient information and have given their written informed consent to participate in the study.

Right to privacy and informed consent

The authors have obtained informed consent from patients and/or subjects referred to in the article. This document is in the possession of the corresponding author.

Conflict of Interest

The authors declare no conflicts of interest.

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Please cite this article as: Pantoja Zarza L, Díez Morrondo C, Manjón Haces JA. Artritis y onicofagia: un factor de confusión. Reumatol Clin. 2014;10:260–261.

Copyright © 2013. Elsevier España, S.L.. All rights reserved
Reumatología Clínica (English Edition)

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