title: Left-sided laterality of Merkel cell carcinoma in a German population: more than just sun exposure.
abstract: BACKGROUND
  Lateral distribution of cancer has been observed previously. Most evident is this laterality in ultraviolet (UV)-induced skin cancer, based on an unequally distributed UV exposure.
  
  
  OBJECTIVE
  The aim of this study was to explore whether patients from Germany also show asymmetrical lateral distribution of Merkel cell carcinoma (MCC).
  
  
  METHODS
  In total, 115 patients with MCC were studied for laterality of the primary tumour. Correlation of clinical variables with lateral distribution of MCC was investigated as well.
  
  
  RESULTS
  In 64/115 (55.7%) patients, primary tumours were present on the left side, in 37/115 (32.2%) on the right side, and in 14/115 (12.2%) in the midline (P < 0.0001). Excluding the latter localization occurrence of left-sided MCCs (64 of 101/63.4%) was significantly (P = 0.0072) more often observed (1.73-fold) when compared to right-sided tumours (37 of 101/36.6%). The excess of left-sided tumours was found on the head with a left-right ratio of 1.8, trunk of 8, arm of 1.2, and leg of 1.8. There was no significant association between laterality and gender, age, MCPyV status, and anatomic localization of primary tumours including the occurrence in sun-exposed sites.
  
  
  CONCLUSIONS
  Occurrence of left-sided MCCs was significantly more often observed when compared to right-sided tumours. Laterality was not associated with tumour presentation at chronically ultraviolet-exposed sites. Hence, the reason for laterality in MCC remains obscure, but likely goes beyond UV exposure.
authors: Department of Dermatology, Skin Cancer Center, Ruhr-University Bochum, Gudrunstraße 56, 44791, Bochum, Germany. t.gambichler@klinikum-bochum.de.
authors: T
authors: T
authors: Gambichler
authors: National Reference Center for Papilloma- and Polyomaviruses, Institute of Virology, University of Cologne, Cologne, Germany.
authors: U
authors: U
authors: Wieland
authors: National Reference Center for Papilloma- and Polyomaviruses, Institute of Virology, University of Cologne, Cologne, Germany.
authors: S
authors: S
authors: Silling
authors: Department of Dermatology, Skin Cancer Center, Ruhr-University Bochum, Gudrunstraße 56, 44791, Bochum, Germany.
authors: M
authors: M
authors: Dreißigacker
authors: Dermatopathology Duisburg, Duisburg, Germany.
authors: J
authors: J
authors: Schaller
authors: Fachklinik Hornheide, Skin Cancer Center, Department of Dermatology and Dermato-Histo-Pathology, Münster, Germany.
authors: H-J
authors: HJ
authors: Schulze
authors: Institute for Pathology, Mülheim/Ruhr, Germany.
authors: F
authors: F
authors: Oellig
authors: Department of Dermatology, Venereology and Allergology, HELIOS St. Elisabeth Hospital Oberhausen, Oberhausen, Germany.
authors: A
authors: A
authors: Kreuter
authors: Department of Dermatology, Skin Cancer Center, Ruhr-University Bochum, Gudrunstraße 56, 44791, Bochum, Germany.
authors: M
authors: M
authors: Stücker
authors: Department of Dermatology, Skin Cancer Center, Ruhr-University Bochum, Gudrunstraße 56, 44791, Bochum, Germany.
authors: F G
authors: FG
authors: Bechara
authors: Department of Dermatology, Skin Cancer Center, Ruhr-University Bochum, Gudrunstraße 56, 44791, Bochum, Germany.
authors: E
authors: E
authors: Stockfleth
authors: Translational Skin Cancer Research, DKTK Partner Site Essen/Düsseldorf, West German Cancer Center, Dermatology, University Duisburg-Essen, Essen, Germany.
authors: J C
authors: JC
authors: Becker
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015266:Carcinoma, Merkel Cell / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D005858:Germany; D006801:Humans; D008297:Male; D012878:Skin Neoplasms / Q000453:epidemiology / Q000473:pathology*; D013472:Sunlight / Q000009:adverse effects
keywords: Lateral distribution; Laterality; Merkel cell carcinoma