A 32-year-old white woman, with a negative personal and family history of malignant melanoma was referred from her dermatologist with a 1-week history of a gradually enlarging nodule within a small congenital nevus, on the upper aspect of her back (Fig 1, top). The patient's nevus had been evaluated on a regular basis by a dermatologist and her medical records indicated that the surface component had not changed over the course of the previous 15 months. Excisional biopsy of the lesion 2 months after initial presentation, demonstrated a malignant melanoma present in the reticular dermis and subcutaneous fat, measuring 22 mm in greatest diameter and arising in contiguity with the dermal component of the nevus (Figs 1, bottom and 2). The tumor nodule was composed of sheets of epithelioid cells with two mitoses per square millimeter. The patient denied having had a history of severe sunburn and was otherwise healthy.
Sharpe RJ, Salasche SJ, Barnhill RL, Sober AJ. Nonepidermal Origin of Cutaneous Melanoma in a Small Congenital Nevus. Arch Dermatol. 1990;126(12):1559-1561. doi:10.1001/archderm.1990.01670360021002