title: Reticular erythematous mucinosis: histopathological and immunohistochemical features of 25 patients compared with 25 cases of lupus erythematosus tumidus.
abstract: OBJECTIVE
  Reticular erythematous mucinosis (REM) and lupus erythematosus tumidus (LET) share similarities. However, to our knowledge no study extensively compared the histological features of these two conditions. The aim of this study is to compare the histological and immunohistochemical features of REM and LET.
  
  
  METHODS
  We evaluated epidermal thickness, hyperkeratosis, dermo-epidermal junction changes, interstitial mucin deposition, vessel dilatation and pattern, type and density of the inflammatory infiltrate in 25 cases of REM and LET. Anti-CD3, anti-CD20, anti-CD68, anti-CD4, anti-CD8, anti-CD123, anti-CD2AP, anti-IgG and anti-C3 antibodies were tested in a subset of patients.
  
  
  RESULTS
  Both diseases are characterized by perivascular dermal infiltrates of lymphocytes mainly CD4+ positive and increased dermal mucin. However, REM tended to show more scattered and more superficial lymphocytes with more superficial mucin and to have less frequent immunoglobulin and complement depositions along the dermo-epidermal junction. Plasmacytoid dendritic cells (PDCs) were less represented in REM, and were mainly found as single cells differently from LET.
  
  
  CONCLUSIONS
  REM and LET present some differences in the infiltrate, including PDCs, the mucin deposition and the immunoreactant deposition at the dermo-epidermal junction that justify the distinction of the two diseases and suggest different pathogenetic mechanisms.
authors.affiliation: Section of Dermatology, Department of Health Sciences (DISSAL), University of Genoa and IRCCS San Martino-IST University Hospital, Genoa, Italy; Section of Dermatology, University Hospital of Saint-Etienne, Saint-Etienne, France.
authors.forename: E
authors.initials: E
authors.lastname: Cinotti
authors.forename: V
authors.initials: V
authors.lastname: Merlo
authors.forename: W
authors.initials: W
authors.lastname: Kempf
authors.forename: C
authors.initials: C
authors.lastname: Carli
authors.forename: J
authors.initials: J
authors.lastname: Kanitakis
authors.forename: A
authors.initials: A
authors.lastname: Parodi
authors.forename: F
authors.initials: F
authors.lastname: Rongioletti
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015496:CD4-Positive T-Lymphocytes; D003713:Dendritic Cells; D004817:Epidermis / Q000473:pathology; D004890:Erythema / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007136:Immunoglobulins / Q000032:analysis; D007150:Immunohistochemistry; D007642:Keratosis / Q000473:pathology; D008178:Lupus Erythematosus, Cutaneous / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D017520:Mucinoses / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D009077:Mucins / Q000032:analysis; D055815:Young Adult
chemical_list: D007136:Immunoglobulins; D009077:Mucins