Transepidermal elimination of mucin is a very common but not yet reported phenomenon in digital myxoid cysts: a study of 35 cases.

We present a series of 35 cases of digital myxoid cyst in which we specifically looked for transepidermal migration of mucin. We found it in 57.14% of the cases (20/35). In these cases, there were collections of mucin in an intraepidermal bulla as well as multiple intercellular droplets of mucin in many cases. All cases of perforating mucinosis described so far in the literature have presented clinically as papular eruptions. We therefore conclude that (1) perforating mucinoses do not exclusively present as multiple papules but also occur as single lesions; (2) transepidermal elimination of mucin is a very common but not yet reported phenomenon in digital myxoid cysts; (3) the morphological findings suggest real transepidermal migration of the mucin instead of exposure of the mucin to the surface via ulceration.