Cytokeratin subtypes and involucrin in squamous cell carcinoma of the vulva. An immunohistochemical study of 41 cases.

BACKGROUND

Histologic grade seems to be of limited prognostic significance in patients with vulvar carcinoma. However, the study of cytokeratin expression is of potential interest because it allows a more precise evaluation of the degree of squamous differentiation. This study was conducted to investigate whether differences in cytokeratin expression exist between normal vulvar epithelium and vulvar carcinoma and whether these differences are prognostically significant.

METHODS

The expression of several differentiation markers, i.e., cytokeratin (CK) 10, CK 13, and involucrin, was studied in samples of 41 vulvar carcinomas. The expression of CK 8, 10, 13, and 14 was compared with CK expression in normal vulvar epithelium and was correlated with tumor grade and tumor growth pattern. Tumor growth pattern was considered type A if infiltrating tumor cell nests showed a layer of small, basaloid cells bordering the surrounding mesenchymal tissue and was considered type B if this was not the case. Prognosis was based on whether disease recurred or not.

RESULTS

Sixteen patients had disease recurrence. No prognostic significance of tumor grade was found. Tumor growth pattern was prognostically significant: in patients with a type A tumor, recurrence was observed less often than in patients with a type B tumor (P = 0.03). Cytokeratin 14, typical for basal cells of normal vulvar epithelium, was expressed in all tumors, whereas CK 8 was not expressed in any tumor. A relationship between tumor growth pattern and the concordant expression of differentiation markers was observed: in 55% of type A tumors and in none of type B tumors, concordant expression of CK 10, CK 13, and involucrin was found.

CONCLUSION

The expression of differentiation markers in vulvar carcinoma is related strongly to the tumor growth pattern, and this pattern is prognostically significant.