[Pretibial epidermolysis bullosa and hypothyroidism]

We report a case of primary non-autoimmune hypothyroidism causing pretibial epidermolysis bullosa.

A 70-year-old man with primary non-autoimmune hypothyroidism developed blisters of different ages on the lateral aspect of both legs. Pathology reported blisters with subepidermal cleavage. Direct immunofluorescence was negative. Electron microscope examination showed a variable cleavage level and diffuse infiltration of a granulous and amorphous microfibrillar substance. After hormone replacement therapy, euthyroidism was associated with a reduction in the number of bullae and finally complete remission. After 12 months follow-up, the patient has not experienced recurrence.

Recurrence-free clinical improvement after hormone replacement therapy suggests the diagnosis of hypothyroidism pretibial epidermolysis bullosae. Mochizuki et al. described a similar case which rapidly regressed after hormone therapy but where the electron microscope showed a different cleavage level. These bullae appear to result from a mechanical mechanism due to their localization in areas exposed to friction and also to the presence of bullae of different ages. This hypothesis is confirmed by the presence of a variable level of cleavage and a substance dense to electrons at electron microscopy as well as by the skin weakness. Our case confirms the reality of hypothyroidism pretibial epidermolysis bullosa. Thyroid hormones should be assayed in patients presenting pretibial bullae.