Respiratory manifestation of yellow nail syndrome: a case report and literature review.

Yellow nail syndrome (YNS) is a rare disorder, and diagnosis is based on the clinical findings and the exclusion of other possible causes; the pathogenesis is poorly understood. YNS can be an isolated condition or associated with other diseases; however, YNS associated with multiple myeloma (MM) is rare. A 53-year-old male patient presented with coughing and shortness of breath, and he was diagnosed with YNS with MM. He underwent chemotherapy and achieved a good response. Although the etiology of YNS remains unknown, treating the underlying disease may help prevent or relieve the clinical signs.