Yellow Nail Syndrome

Yellow nail syndrome (YNS) is a rare condition defined by the presence of 2 of the following 3 symptoms: 1. Slow-growing, hard, yellow, and dystrophic nails. 2. Lymphedema. 3. Respiratory tract disease  . The earliest case of YNS was reported by Heller in 1927. However, in 1947, Samman and  White published the first case series of YNS in patients with nail discoloration and lymphedema. Pulmonary disease, specifically pleural effusion, was added to the diagnostic criteria by Emerson in 1966. The syndrome generally affects adults aged 50 and older. However, case reports of YNS occur in children and even newborns. Anatomically, YNS affects the fingernails, toenails, the respiratory tract, and gravity-dependent areas that can accumulate fluid (typically lower extremities). These signs and symptoms are believed to be due to dysfunction in lymphatic drainage. As the name suggests, xanthonychia (yellow nail coloration) is a common feature of YNS; however, yellow nails are not required if 2 of the other clinical signs are present. Discoloration varies from pale yellow to dark green; nails can be opaque or translucent. The manifestations are commonly misdiagnosed as onychomycosis (discoloration due to fungal infection), as the nails may become thickened, hard, and curved. A quick inspection of fingernails and toenails can help expand the differential for a patient with other vague complaints without additional expense. The respiratory tract is involved in more than half of patients with YNS. The most common manifestation is a chronic cough, followed by pleural effusion. In one of the largest reviews of patients with YNS, Valdés et al found nearly all effusions exudative with a lymphocytic predominance. Of the 66 subjects, approximately 70% of effusions were bilateral. Other pulmonary manifestations include bronchiectasis, recurrent pneumonia, sinusitis, and pulmonary fibrosis. Pulmonary function testing in YNS is typically unremarkable, and biopsies do not usually contribute to the diagnosis. Lymphedema typically manifests in the bilateral lower extremities and does not differ in appearance from primary lymphedema. Lymphedema occurs in 30% to 80% of patients. Dynamic lymphatic imaging (lymphoscintigraphy) does differ between patients with edema related to YNS and those with primary lymphedema. Edema can be pitting and can be easily confused with fluid accumulation, often seen in patients with decompensated congestive heart failure. This can be especially deceiving if patients present with concurrent pleural effusions. As in primary lymphedema, treatments often involve massage, compression dressing, exercises, and, less commonly, surgical interventions. The diagnosis of YNS can be difficult because patients rarely present concurrently with all 3 clinical criteria. Lymphedema is the initial symptom in approximately one-third of YNS diagnoses. The prognosis and disease course depend on the individual's symptoms and the timing of diagnosis. In some mild cases, the symptoms of YNS can be resolved without intervention. Unfortunately, many symptoms recur despite treatment and require continuous care. YNS can negatively affect one's quality of life, including cosmesis and worsening functional status. Recurring soft tissue infections (eg, cellulitis from severe lymphedema), pulmonary infections (pneumonia/empyema), and pulmonary effusions can lead to complications such as antibiotic resistance, pulmonary scarring, and protein loss.