Expression of mutant p53 gene in squamous carcinoma arising in patients with recessive dystrophic epidermolysis bullosa.

Epidermolysis bullosa, a rare genodermatosis, is characterized by increased skin fragility manifest as blistering and sometimes accompanied by scarring. The latter is particularly severe in the recessive dystrophic variant and may be complicated by the development of squamous carcinoma in up to 30% of patients. We have studied 23 such tumours in six patients with this variant, with an anti-serum to p53 protein. Twenty-six per cent of the squamous carcinomas labelled positively for mutant-type p53 protein. This low figure, however, reflects the large number of well-differentiated tumours in this series, where 14 out of 15 were negative. In the moderate to poorly differentiated examples the positivity rate was 63%. Of the three patients in the latter category, one has died from disseminated tumour and another has widespread metastases. The findings support the hypothesis that mutant p53 protein expression correlates with poorer tumour differentiation. They also suggest a possible correlation between p53 protein expression and tumour behaviour.