A case of angiokeratoma circumscriptum: immunolocalization of matrix metalloproteinase (MMP)-9.

We report a case of angiokeratoma circumscriptum which we have followed for one year. The skin lesion initially showed erythema and then changed to a dark reddish, raised, keratotic nodule. The lesion histologically showed dilated capillaries and hyperkeratosis. Using immunohistochemistry, matrix metalloproteinase (MMP)-9 was localized in the epidermis just under the horny layer, particularly in the hyperkeratotic lesion. The expression of MMP-9 might be related to the hyperkeratotic changes in this lesion.