Squamous cell carcinoma of the skin--histopathological features and their significance for the clinical outcome.

BACKGROUND

Owing to the rising incidence of tumours, the question of reliable risk classification is becoming increasingly significant.

OBJECTIVE

Participation in the multicentre carcinoma registry maintained by the Association of Operative and Oncological Dermatology of the German Dermatological Society requires, in addition to the parameters of clinical staging and grading already established by the International Union against Cancer, description of other histopathological criteria related to prognosis, with special attention to microstaging.

METHODS

One hundred and eighty-four patients with squamous cell carcinoma of the skin were examined. The histological parameters, carcinoma type, Breslow index, invasion level, growth form, grading and mitotic index were recorded and classified, and clinical staging was performed.

RESULTS

It was found that the clinical criterion of tumour diameter (T-category) determines the further course of the disease. The other parameters taken into account, namely pathohistological microstaging and grading, can increase the accuracy of prognosis evaluation, and in particular enable carcinomas of the T1-category to be classified as either high malignant or low malignant tumours. The desmoplastic squamous cell carcinoma subtype is a potential risk tumour. Endophytic tumours are more malignant in their development than exophytically-growing carcinomas, and the probability of recurrence and metastatic tumour spread further increases when ulceration can be detected by microscope. In order to distinguish metastatic and recurring carcinomas, in addition to determining the invasion levels after Clark, measuring the Breslow index proved to be an important criterion. Quoting the mitotic index augmented the grading system, which further improved the reliability of malignancy assessment.

CONCLUSIONS

The TNM categories currently applied to squamous cell carcinomas of the skin must be supplemented by additional histological parameters which, according to our findings, permit more accurate classification of high and low malignant tumours.