Yellow nail syndrome (YNS) is a very rare syndromic disorder characterized by the variable triad of characteristic yellow nails, chronic respiratory manifestations, and primary lymphedema.
Prevalence and incidence rates are not known, but YNS is considered a very rare condition. More than 150 cases have been reported to date. The disorder affects males and females equally.
The clinical signs of YNS usually develop after puberty but there is wide variability in the age of onset. Most cases are of late onset, after 50 years of age. Patients generally complain of slowed or arrested nail growth: the nails become thickened and opaque, with yellowish or green discoloration and that lack the cuticles. Increased transverse curvature is another feature, which may lead to nail plate detachment. Nail changes tend to affect all 20 nails but the severity is variable. Lymphedema is the most consistent associated finding and usually affects the lower limbs. YNS may be associated with respiratory involvement with chronic cough, bronchitis, tracheobronchitis, bronchiectasis, chronic sinusitis, and pleural effusions. Some patients have all three signs in the triad, while others have nails change with lymphedema or respiratory disorders, or nail changes alone. YNS may also be a paraneoplastic disorder.
The etiology of YNS has not been elucidated. It is thought to be caused by an underlying lymphatic abnormality, with reduced lymphatic drainage.
Diagnosis is usually based on the presence of two of the three classic clinical manifestations, including nail changes, respiratory disorders and lymphedema, or on highly characteristic nail changes. This is because the three main signs may not be present all at once in the patient. Diagnosis can also be based on the typical nail changes alone.
The most important nail differential diagnoses include chronic paronychia, which shares absence of the cuticle and nail thickening and discoloration, and onychomycosis of the toenails, which produces thickening and onycholysis. Onychogryphosis and acquired pachyonychia should also be considered.
Spontaneous improvement in nail signs is reported in up to 30% of cases. Systemic vitamin E at a daily dose of 1,200 IU has been reported to be effective in more than half of patients.
Some patients recover fully but the respiratory condition and the associated symptoms are often chronic. Serious lymphedema and respiratory complications may affect quality of life and periodic follow-up is mandatory.
Last update: March 2014
- Dr Riccardo BALESTRI
- Pr Bianca PIRACCINI