Differential diagnosis of keratoacanthoma and squamous cell carcinoma of the epidermis by MIB-1 immunohistometry.
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.
Biesterfeld
Stefan
S
Institute of Pathology, Technical University of Aachen, Pauwelsstr. 30, 52074 Aachen, Federal Republic of Germany. Biesterfeld@pat.rwthaachen.de
Josef
Juliana
J
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
D019394:Ki-67 Antigen