[Nevus eruption following thyroidin with spontaneous involution].

Report on a young girl with eruptive manifestation of multiple nevuscell nevi following unnecessary treatment with thyroid extract at the age of 13. When this treatment was stopped at age 19, most of the nevi diminuted. Many of them disappeared within a short time, some with halo formation. This case report shows a new side effect of thyroid extract therapy. It is also interesting with regard to pigment cell regulation.