Differentiation between malignant and benign follicular adnexal tumours of the skin by DNA image cytometry.
Background: We have demonstrated in previous studies that DNA image cytometry (DNA ICM) can be helpful in detecting malignancy in sebaceous tumours of the Muir-Torre syndrome and sweat gland tumours. However, little is known about DNA ICM in cutaneous adnexal tumours with follicular differentiation.
Objective: To study a larger series of benign and malignant follicular adnexal tumours with DNA ICM.
Methods: We studied 13 malignant follicular tumours (seven trichilemmal carcinomas, five malignant proliferating pilar tumours, one pilomatrix carcinoma) and 55 benign follicular tumours (four tumours of the follicular infundibulum, seven Winer's pores, eight trichilemmomas, two trichofolliculomas, 16 trichoepitheliomas, 13 pilomatrixomas, five trichoblastomas) by DNA ICM. All cases were clear-cut as malignant or benign, respectively, on histopathological criteria. The stemline interpretation according to Böcking et al. (DNA distribution in gastric cancer and dysplasia. In: Precancerous Conditions and Lesions of the Stomach, Zhang YC, Kawai K, eds. Berlin: Springer-Verlag, 1993: 103-20) was performed in all cases. In addition, 5[c]-exceeding events (5cEE) and the 2[c] deviation index (2cDI) were calculated, except in one histopathologically benign tumour, which revealed euploid polyploidization, as the analysis of 5cEE and 2cDI is not valid in that case.
Results: A 2cDI threshold of 0.24 proved to be the most reliable marker for the distinction between malignant and benign follicular tumours. On the basis of this feature, all malignant and benign tumours were correctly classified. A specificity of 100% was achieved by all three interpretation methods, but the sensitivity of 2cDI for the detection of malignant tumours was superior to the analysis of 5cEE (sensitivity 77%) and to the stemline interpretation (sensitivity 23%).
Conclusions: DNA ICM may be helpful in distinguishing between malignant and benign follicular tumours.