Background: Large congenital nevi carry a slightly increased risk of melanoma. Pregnancy poses an additional challenge in the monitoring of these patients because little is known regarding the effects of increased estrogen levels on congenital nevi.
Observations: A young woman was observed to have clinical lightening of her garment nevus and satellite nevi during 2 sequential pregnancies. Postpartum, the patient experienced darkening and repigmentation in her large garment nevus, with continued lightening of nearby satellite lesions. In addition to photographic documentation of these changes, biopsy samples taken during pregnant and nonpregnant periods underwent immunohistochemical evaluation for estrogen receptor beta (ERbeta), the predominant estrogen receptor in nevi and melanomas. Biopsy samples collected during pregnancy showed a decrease in nuclear staining for ERbeta compared with samples collected after pregnancy. These changes in ERbeta expression were not associated with histologic atypia during pregnancy or after delivery.
Conclusions: Congenital nevi may be unique in their response to altered estrogen levels. Given the slightly increased risk of melanoma in giant congenital nevi and the dearth of information available regarding the effects of pregnancy on congenital nevi, this case illustrates the need for further study of these pigmented lesions.