title: Polydactylous Transverse Erythronychia: Report of a Patient with Multiple Horizontal Red Bands Affecting the Fingernails.
abstract: BACKGROUND
  Redness of the nail plate-erythronychia-is a common condition involving one or multiple digits. It may affect the entire nail or present as longitudinal red bands that extend from the proximal nail fold to the distal tip of the nail plate. Rarely, red bands may traverse the nail bed horizontally. Although erythronychia is often idiopathic, it has also been associated with amyloidosis, Darier's disease, lichen planus, and various other cutaneous conditions. We describe the clinical features of a 64-year-old Caucasian man who presented with transverse and longitudinal erythronychia affecting his fingernails. In addition, we review the classification of erythronychia and summarize the acute and chronic conditions that have been associated with this clinical finding.
  
  
  METHODS
  The features of a man with polydactylous transverse and longitudinal erythronychia are presented. In addition, PubMed was used to search the following terms: erythronychia, longitudinal erythronychia, red lunulae, and subungual. All papers were reviewed, and relevant articles, along with their references, were evaluated. Informed consent was obtained from the patient for being included in the study.
  
  
  RESULTS
  A 64-year-old Caucasian man with a past medical history significant for testicular cancer and pulmonary embolism presented with multiple horizontal pink-red bands affecting his fingernails. The discoloration was most prominent in the region distal to the lunula. In addition, the nails of the fifth digit of his left hand and third digit of his right hand featured longitudinal red bands extending from the distal curvature of the lunula to the free edge of the nail plate. A diagnosis of polydactylous longitudinal and transverse erythronychia, based on the clinical presentation, was established. Our patient's red bands were asymptomatic and he was not concerned about the cosmetic appearance of his nails; therefore, no additional investigation or treatment was required.
  
  
  CONCLUSIONS
  Polydactylous transverse erythronychia is a rare condition characterized by the development of horizontal red bands affecting the fingernails or toe nails. It has only been previously described in a man with multiple system atrophy. In our patient, both transverse and longitudinal red bands were present simultaneously. Therefore, it is possible that horizontal erythronychia is an early clinical manifestation of longitudinal erythronychia.
authors.affiliation: Reno School of Medicine, University of Nevada, Reno, NV, USA.
authors.forename: Carina
authors.initials: C
authors.lastname: Chang
authors.affiliation: Reno School of Medicine, University of Nevada, Reno, NV, USA.
authors.forename: Bryce D
authors.initials: BD
authors.lastname: Beutler
authors.affiliation: Department of Dermatology, University of California San Diego, San Diego, CA, USA. mitehead@gmail.com.
authors.forename: Philip R
authors.initials: PR
authors.lastname: Cohen
keywords: Erythronychia; Longitudinal erythronychia; Red lunulae; Subungual; Transverse erythronychia