p16 expression in keratoacanthomas and squamous cell carcinomas of the skin: an immunohistochemical study.
BACKGROUND
Distinguishing between keratoacanthoma (KA) and squamous cell carcinoma (SCC) is not an uncommon histologic diagnostic dilemma.


OBJECTIVE
To determine if p16 expression is useful in the differential diagnosis of SCC and KA.


METHODS
We studied the expression of p16 by immunohistochemistry in 24 KAs, 24 infiltrating SCCs of the skin, 4 histologically indeterminate lesions, and 8 nonmalignant keratoses.


RESULTS
A range of immunohistochemical p16 expression was seen in KAs and SCCs in terms of the thickness of lesional staining and the percentage of cells staining. No significant difference in measures of p16 expression was identified among the KAs, the SCCs, the indeterminate lesions, or the benign keratoses.


CONCLUSIONS
These findings suggest that p16 is not a useful marker to distinguish between KA and SCC, supporting the similarity between the 2 lesions; p16 alterations appear to play a role in the pathogenesis of both KA and SCC.
Kaabipour
Emad
E
Department of Pathology, Pennsylvania Hospital, Philadelphia, PA 19107, USA.
Haupt
Helen M
HM
Stern
Jere B
JB
Kanetsky
Peter A
PA
Podolski
Victoria F
VF
Martin
Anne-Marie
AM
D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D002452:Cell Count; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007636:Keratoacanthoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D007642:Keratosis / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology
D014408:Biomarkers, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16