INVOLUCRIN AND TUMOR PROGRESSION IN THE UTERINE CERVIX

The expression of involucrin, a cytoplasmic protein synthesized during squamous maturation, was assessed by immunocytochemistry in different grades of cervical lesions. In normal/benign cervical epithelium and low-grade squamous intraepithelial lesions [SILS or cervical intraepit helial neoplasia (CIN)-1] involucrin showed intense and homogenous cyt oplasmic expression in the spinal layers of 75 and 57% of samples, res pectively. The basal cell layers showed no expression of involucrin. I n high-grade SILs (CIN-2/3) 40% of the samples showed diffuse and foca l cytoplasmic expression of involucrin in the differentiated basaloid cells. In the squamous cell carcinomas (SCCs) analyzed, well-different iated tumors showed intense focal expression in 61% of the cases, mode rately differentiated SCCs showed intense expression in 33% of the cas es, while poorly differentiated SCCs (PDSCC) showed only a mild focal expression in 7% of cases. With increasing severity of the lesions, pa tchy expression of involucrin with a mixture of reactive and nonreacti ve cells predominated. Patterns of immunocytochemical staining for inv olucrin in cervical lesions of different grades, from low-grade to hig h-grade SILs, and invasive carcinoma may be of critical importance, if loss of involucrin expression is used as a criterion for neoplastic t ransformation in cervical epithelium. Our findings suggest that involu crin may be a sensitive marker in identifying the differentiation stat us of the lesion while the absence of involucrin in PDSCC may be helpf ul in differential diagnosis.