Melanoma with complete regression, light micrograph. Histologic evidence of partial regression is seen in 10-35% of primary cutaneous melanomas. In a small number of cases, melanomas regress completely after giving rise to nodal or distant metastases. In 5-15% of cases of metastatic melanoma, the primary tumour is never found, presumably due to complete regression. Clinically, regression appears as macular gray, white, or pink areas with granularity. The regressed areas show a dermal lymphocytic infiltrate, absence of atypical melanocytic nests from the epidermis overlying the dermal infiltrate, epidermal atrophy with flattening of rete ridges, and pigment-laden macrophages. All of these features are seen in this image. |