Nevi Related to Thyroid Diseases

It is well established that certain hormones induce, maintain, or interfere with the clinical evolution of some pigmentary lesions. This occurs in specific periods of life because of hormonal activity, such as that of growth hormone or estrogens during puberty and pregnancy. Exogenous hormones, for example from oral contraception and treatments for growth hormone deficiencies, can exert a marked influence on pigmentary lesions. In vivo and in vitro studies confirm this influence of exogenous hormones on melanocyte homeostasis. A recent study performed on children with growth disorders demonstrates the effect of growth hormone on melanocyte proliferation.¹ Estrogen receptors have been found in melanocytes whose prognostic value in the progression and metastases of melanoma is debatable.² However, there are no references in the medical literature to the possible influence of thyroid hormones on normal epidermal melanocytes and nevic cells, other than the well-known association between vitiligo and thyroid dysfunction.³ We describe 2 patients in whom there was apparently a temporal association between thyroid dysfunction or treatment and clinical and histological signs of melanocytic proliferation.