Dystrophic epidermolysis bullosa hereditaria are genodermatosis responsible for formation of cutaneous bullous lesion arising spontaneously or after mechanical trauma.

These lesions are due to mutation on gene COL7A1 coding for collagen VII. There is no treatment available. Cares are consisting to dress lesions and to protect the skin.

The investigators have recently observed on patients having residual expression of collagen VII that phenotype severity is modulated by activation degree of dermic metalloproteinase. The investigators have also observed that epigallocatechin-3-gallate (Polyphenon E®) could be regulated this activity.

The primary purpose of this study is to assessing the efficacity of Polyphenon E to decrease the number of cutaneous bullosa after four month of treatment.

The primary outcome measure is the rate of patient presenting a decrease of 20% or more of the number of cutaneous bullosa.

Secondary outcomes are: severity of mucosa impairment, affected cutaneous surface, the average duration of cicatrisation and treatment tolerance.

This study foresees the inclusion of 22 patients older than 2 years old in 5 centers.

When patients are included, they will be randomized and receive the treatment (or placebo) for 4 months.

Inclusion Criteria:

• known mutation of COL7A1

Exclusion Criteria:

• tea drinkers
• patient receiving induction treatment,protease inhibitor treatment
• liver failure