title: Diagnostic approach in lymphoplasmacytic plaque.
abstract: BACKGROUND
  Lymphoplasmacytic plaque (LPP) is a recently described rare skin disease characterized by a dense dermal lymphohistiocytic infiltrate with polyclonal plasma cells. The clinical picture is distinct with reddish to brownish plaque with a predilection for the lower leg. LPP typically affects children.
  
  
  OBJECTIVE
  To define clinical and histologic criteria of LPP and to develop a diagnostic flow chart.
  
  
  METHODS
  We investigated six of our own LPP cases. Immunoglobulin light chains, IgG, IgG4, CD31, CD163 as a histiocytic marker were examined by immunohistochemistry. PCR-based molecular studies were conducted for borrelia sp., mycobacterial and leishmania sp. Moreover, 10 cases, which have been reported in the literature, were checked for the same features.
  
  
  RESULTS
  We could differentiate three main histological patterns (superficial band-like only, [deep] dermal only and mixed). Acanthosis and interface dermatitis are key features in cases with a superficial band-like or mixed infiltrate. Granulomas and giant cells could be only found in about 30% of the cases. The number of plasma cells was variable accounting for 5-40% of the infiltrate. The number of blood vessels was increased in the majority of the cases. 'Free-floating' collagen bundles surrounded by histiocytes (pseudorosettes) were identified as a new histological feature. An infectious agent could be excluded in all cases.
  
  
  CONCLUSIONS
  LPP is a long-standing skin disease, which may also occur in adults and in other body regions than the lower leg. Reproducible clinical and histological criteria allow delineating a diagnostic work-up for LPP.
authors.affiliation: Department of Dermatology, HELIOS Klinikum Hildesheim GmbH, Hildesheim, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Mitteldorf
authors.affiliation: Dermatopathologie Friedrichshafen Bodensee, Bodensee, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Palmedo
authors.affiliation: Dermatopathologie Friedrichshafen Bodensee, Bodensee, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Kutzner
authors.affiliation: Medizinisches Versorgungs-Zentrum Charlottenburg, Berlin, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Kauer
authors.affiliation: Hautzentrum Dr. Martin Kägi, MD, Zürich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Prestin
authors.affiliation: Dermatology Practice, St. Gallen, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Schuster
authors.affiliation: Dermatology Practice, Biel, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Hübscher
authors.affiliation: Dermatology Unit, Kantonsspital Lucerne, Lucerne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Kirsch
authors.affiliation: Department of Dermatology, HELIOS Klinikum Hildesheim GmbH, Hildesheim, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Tronnier
authors.affiliation: Kempf und Pfaltz, Research Unit, Histologische Diagnostik, Zürich, Switzerland.
authors.forename: W
authors.initials: W
authors.lastname: Kempf
mesh_terms: D000293:Adolescent; D000368:Aged; D015703:Antigens, CD / Q000032:analysis; D015214:Antigens, Differentiation, Myelomonocytic / Q000032:analysis; D001808:Blood Vessels / Q000473:pathology; D025065:Borrelia burgdorferi / Q000235:genetics / Q000302:isolation & purification*; D002648:Child; D002675:Child, Preschool; D003094:Collagen / Q000648:ultrastructure; D004269:DNA, Bacterial / Q000032:analysis*; D016054:DNA, Protozoan / Q000032:analysis*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007147:Immunoglobulin Light Chains / Q000032:analysis; D007891:Leishmania / Q000235:genetics / Q000302:isolation & purification*; D008297:Male; D008875:Middle Aged; D009161:Mycobacterium / Q000235:genetics / Q000302:isolation & purification*; D010950:Plasma Cells / Q000473:pathology; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D011956:Receptors, Cell Surface / Q000032:analysis; D012867:Skin / Q000098:blood supply / Q000737:chemistry*; D012871:Skin Diseases / Q000378:metabolism* / Q000473:pathology*; D055815:Young Adult; D000098902:CD163 Antigen
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D000098902:CD163 Antigen; D004269:DNA, Bacterial; D016054:DNA, Protozoan; D007074:Immunoglobulin G; D007147:Immunoglobulin Light Chains; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011956:Receptors, Cell Surface; D003094:Collagen