title: Seborrheic keratosis of conjunctiva simulating a malignant melanoma: an immunocytochemical study with impression cytology.
abstract: OBJECTIVE
  Seborrheic keratosis on the conjunctiva appears to have never been reported in the literature. The authors report here a well-documented case of seborrheic keratosis of conjunctiva clinically simulating a malignant melanoma.
  
  
  METHODS
  Case report.
  
  
  METHODS
  A 66-year-old man presented with a juxtalimbal pigmented tumor involving the temporal conjunctiva of his left eye. Because of the rapid enlargement of the mass within a period of 5 months, a clinical diagnosis of malignant melanoma was made. Cytopathologic examinations were performed by impression cytology before the patient underwent a wide en-block excision of the tumor.
  
  
  METHODS
  Cytologic features were studied by impression cytology with periodic acid-Schiff-Papanicolaou stain. Immunochemical characteristics of tumor cells were studied by immunochemical stain of cytokeratin and HMB-45. Tumor morphology was observed by histopathologic examination.
  
  
  RESULTS
  Impression cytology disclosed basaloid cells intermixing with squamoid cells, and these cells demonstrated positive immunoreactivity to cytokeratin and no reactivity to HMB-45. Histopathologic examination of the tumor specimen established the diagnosis of seborrheic keratosis, and the results of immunohistochemical staining were consistent with those of the impression cytology with immunocytochemical staining.
  
  
  CONCLUSIONS
  The authors describe the first case report of conjunctival seborrheic keratosis and present its immunocytochemical and immunohistochemical characteristics. Such a benign lesion can clinically mimic a malignant melanoma.
authors.affiliation: Department of Ophthalmology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC. shtseng@mail.ncku.edu.tw
authors.forename: S H
authors.initials: SH
authors.lastname: Tseng
authors.forename: Y T
authors.initials: YT
authors.lastname: Chen
authors.forename: F C
authors.initials: FC
authors.lastname: Huang
authors.forename: Y T
authors.initials: YT
authors.lastname: Jin
mesh_terms: D000368:Aged; D000951:Antigens, Neoplasm / Q000378:metabolism; D003229:Conjunctival Diseases / Q000378:metabolism / Q000473:pathology*; D003230:Conjunctival Neoplasms / Q000175:diagnosis / Q000378:metabolism; D003937:Diagnosis, Differential; D006801:Humans; D007124:Immunoenzyme Techniques; D007633:Keratins / Q000378:metabolism; D017492:Keratosis, Seborrheic / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008545:Melanoma / Q000175:diagnosis* / Q000378:metabolism; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins; D007633:Keratins