title: Neoplasia versus hyperplasia of the retinal pigment epithelium. A comparison of two cases.
abstract: OBJECTIVE
  To present the clinical and histopathological characteristics of two different tumor-like lesions of the retinal pigment epithelium (RPE).
  
  
  METHODS
  Two cases of tumor-like lesions of the RPE were identified in the files of the Eye Pathology Institute. The clinical characteristics and the light- and electron microscopical morphology of the lesions were compared and the diagnoses were re-evaluated applying modern immunostainings.
  
  
  RESULTS
  Clinically, both adenoma and tumor-like hyperplasia of the RPE may present with prominent retinal feeder arterioles. The lesions are hypofluorescent in the filling phases and have multiple hyperfluorescent zones in the late phase in fluorescein angiography. They show high internal reflectivity by A-scan and appear as solid tumors by B-scan ultrasonography. Histologically, the two presented lesions of the RPE are different. The first is an adenoma of the vacuolated subtype. The other lesion is a hyperplasia of the RPE disclosing a tubular morphology. The pathologically active cells in both cases were positive for the reaction with antibodies against: cytokeratin, NSE, vimentin, S-100, HMB-45, desmin and SMA. However, only the adenoma was sporadic melan-A positive.
  
  
  CONCLUSIONS
  Adenomas and tumor-like hyperplastic lesions of the RPE are very rare lesions. They share many morphological and immunohistological characteristics. Of the presented cases only the RPE adenoma is sporadic melan-A positive.
authors.affiliation: Eye Pathology Institute, University of Copenhagen, Frederik V's Vej 11, DK-2100 Copenhagen Ø, Denmark. sh@eyepath.ku.dk
authors.forename: S
authors.initials: S
authors.lastname: Heegaard
authors.forename: J N
authors.initials: JN
authors.lastname: Larsen
authors.forename: H C
authors.initials: HC
authors.lastname: Fledelius
authors.forename: J U
authors.initials: JU
authors.lastname: Prause
mesh_terms: D000236:Adenoma / Q000737:chemistry / Q000000981:diagnostic imaging / Q000473:pathology*; D000368:Aged; D000951:Antigens, Neoplasm / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D006965:Hyperplasia; D058965:MART-1 Antigen; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis; D010857:Pigment Epithelium of Eye / Q000737:chemistry / Q000473:pathology*; D019572:Retinal Neoplasms / Q000737:chemistry / Q000000981:diagnostic imaging / Q000473:pathology*; D014463:Ultrasonography
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins