title: Decreased CD44 expression and stromal hyaluronate accumulation in myxoid dermatofibroma.
abstract: BACKGROUND
  Dermatofibroma (DF) is a common benign histiocytic tumor, which has several clinicopathological variants. Myxoid DF is one of these variants, which is characterized by a stromal mucin deposition. CD44 is a polymorphic transmembrane glycoprotein and the principal cell surface receptor of hyaluronate (HA), the major component of the extracellular matrix. In a recent study, we have observed an abnormal accumulation of HA in the superficial dermis of transgenic mice with a keratinocyte-specific CD44 expression defect. We have also shown that HA was accumulated in large amounts in the superficial dermis of lichen sclerosus et atrophicus (LSA) lesions and that the epidermal CD44 expression of LSA skin was significantly decreased or lost. In an another study, we have suggested that a decrease in CD44 expression in follicular epithelial proliferations might be correlated with an abnormal HA accumulation in perifollicular solitary cutaneous myxoma. Recently we have also demonstrated that classical DF lesions displayed a strong CD44 expression in tumor cells and a weak HA positivity in tumor stroma whereas CD44 expression was significantly reduced or absent in dermatofibrosarcoma lesions and the tumor stroma showed strong HA staining.
  
  
  OBJECTIVE
  Here we present 3 cases of myxoid DF, in which we explored the nature of the mucinous material in myxoid stroma by colloidal iron and hyaluronic acid binding protein stainings, as well as the expression of CD44 in the tumor cells by immunohistochemistry.
  
  
  RESULTS
  We show that HA is accumulated in the stroma of all myxoid DF lesions with a significant decrease in CD44 expression in the tumor cells.
  
  
  CONCLUSIONS
  Our results suggest that a decrease in CD44 expression in the tumor cells may result in stromal myxoid changes characterized by an abnormal HA accumulation in myxoid DF.
authors.affiliation: Department of Dermatology, Fatih University Medical Faculty, Ankara, Turkey.
authors.forename: Emel
authors.initials: E
authors.lastname: Calikoglu
authors.forename: Pierre
authors.initials: P
authors.lastname: Chavaz
authors.forename: Jean-Hilaire
authors.initials: JH
authors.lastname: Saurat
authors.forename: Gürkan
authors.initials: G
authors.lastname: Kaya
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis*; D001707:Biopsy, Needle; D005260:Female; D005500:Follow-Up Studies; D018219:Histiocytoma, Benign Fibrous / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D018960:Hyaluronan Receptors / Q000032:analysis / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D018960:Hyaluronan Receptors