title: Adhesion molecules CD171 (L1CAM) and CD24 are expressed by primary neuroendocrine carcinomas of the skin (Merkel cell carcinomas).
abstract: BACKGROUND
  The neuroendocrine carcinoma of the skin is a rare malignant neuroendocrine tumor, which frequently metastasizes in regional lymph nodes or visceral organs. As adhesive interactions with endothelia, leukocytes, or thrombocytes enable malignant cells to penetrate the endothelium and to circulate in blood or lymphatic vessels, we here addressed the adhesion molecules CD171 (L1CAM) and CD24, which are known to be expressed by neurons, neuroblastomas, and other malignant tumors.
  
  
  METHODS
  Thirty-one neuroendocrine carcinomas of the skin (22 primary tumors, four recurrent tumors, and five metastases) were included in the study. Immunohistochemical staining of CD171 and CD24 was performed by the streptavidin-biotin-peroxidase-complex technique and a nickel-enhanced diaminobenzidine (DAB) reaction using the monoclonal antibodies UJ 127.11 and ML-5, respectively.
  
  
  RESULTS
  CD171 expression was detected in most neuroendocrine carcinomas of the skin, and staining was less frequent in metastases and recurrences in comparison with primary tumors which was statistically significant. The majority of neuroendocrine carcinomas of the skin was also positive for the mucin-like adhesion protein CD24. In contrast to tumor cells, cytokeratin 20-positive Merkel cells in 12 trichoblastomas and one fibroepithelioma of Pinkus were all negative for CD171 and CD24 staining.
  
  
  CONCLUSIONS
  Expression of CD171 and CD24 is found in most neuroendocrine carcinomas of the skin, which may be used diagnostically. Further studies will assess whether this feature may contribute to metastasis of neuroendocrine carcinomas of the skin by facilitating transendothelial migration or tumor cell dissemination as has been suggested for other malignancies.
authors.affiliation: Department of Dermatology, Heidelberg University Clinics, Heidelberg, Germany. martin.deichmann@med.uni-heidelberg.de
authors.forename: Martin
authors.initials: M
authors.lastname: Deichmann
authors.forename: Hjalmar
authors.initials: H
authors.lastname: Kurzen
authors.forename: Ursula
authors.initials: U
authors.lastname: Egner
authors.forename: Peter
authors.initials: P
authors.lastname: Altevogt
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hartschuh
mesh_terms: D015703:Antigens, CD / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism; D051927:CD24 Antigen; D015266:Carcinoma, Merkel Cell / Q000378:metabolism* / Q000556:secondary; D006801:Humans; D007124:Immunoenzyme Techniques; D008198:Lymph Nodes / Q000378:metabolism / Q000473:pathology; D008207:Lymphatic Metastasis / Q000473:pathology; D008562:Membrane Glycoproteins; D009364:Neoplasm Recurrence, Local / Q000378:metabolism / Q000473:pathology; D039842:Neural Cell Adhesion Molecule L1 / Q000378:metabolism*; D012878:Skin Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D015703:Antigens, CD; D014408:Biomarkers, Tumor; D051927:CD24 Antigen; C497889:CD24 protein, human; D008562:Membrane Glycoproteins; D039842:Neural Cell Adhesion Molecule L1