title: Differential diagnosis of keratoacanthoma and squamous cell carcinoma of the epidermis by MIB-1 immunohistometry.
abstract: OBJECTIVE
  For the analysis of cellular proliferative activity, the MIB-1 immunopositivity of keratoacanthoma (KA, n = 49), squamous cell carcinoma (SCC, n-48) and each of four cases diagnosed probably as KA or probably as SCC were analyzed by means of immunohistometry.
  
  
  METHODS
  Immunohistochemical reactions were performed on 3-micron sections from routinely formalin-fixed and paraffin-embedded surgical specimens, using an indirect peroxidase method. The rate of immunostained cells was determined using a TV-image analysis system CM-2 (Hund, Germany). Twenty viewing fields (0.97 mm2) were measured with 20:1 objective magnification. An average of 1688 cells were assessed in each case.
  
  
  RESULTS
  The mean MIB-1 immunopositivity (MIB-1mean) was higher in SCC (42.3% +/- 19.1%) than in KA (26.8% +/- 9.8%). The distribution of the single values differed significantly (p = 0.0002). To test the suitability of MIB-1 immunohistometry for the differential diagnosis between KA and SCC, various thresholds were investigated. Using a threshold of 30%, SCC can be detected with a sensitivity of 70.8% (34 out of 48) and a specificity of 67.3% (33 out of 49). If a specificity of > or = 85% is required (42 out of 49, 85.7%), the sensitivity of the test decreases to 56.3% (27 out of 48) based on a threshold of 37.5%. Using the MIB-1 value of the most positive focus of the lesion (MIB-1max), the results were of minor significance; at a specificity level of > or = 85% (42 out of 49, 85.7%) a sensitivity rate of only 43.8% (21 out of 48) could be obtained (threshold: 75%).
  
  
  CONCLUSIONS
  As some overlap of the single values has to be considered, MIB-1 immunohistometry, although presenting new insights into the proliferative potential of KA and SCC, is of only limited value for the differential diagnosis of the two lesions in routine surgical pathology.
authors.affiliation: Institute of Pathology, Technical University of Aachen, Pauwelsstr. 30, 52074 Aachen, Federal Republic of Germany. Biesterfeld@pat.rwthaachen.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Biesterfeld
authors.forename: Juliana
authors.initials: J
authors.lastname: Josef
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D002455:Cell Division / Q000502:physiology; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007636:Keratoacanthoma / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D019394:Ki-67 Antigen / Q000378:metabolism*; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology
chemical_list: D019394:Ki-67 Antigen