SUMMARY Malignant melanoma is characterized by frequent metastasis, however specific changes that regulate this process have not been clearly delineated. Although it is well known that Wnt signaling is frequently dysregulated in melanoma, the functional implications of this observation are unclear. By modulating β-catenin levels in a mouse model of melanoma that is based on melanocyte-specific Pten loss and BrafV600E mutation, we demonstrate that β-catenin is a central mediator of melanoma metastasis to lymph node and lung. In addition to altering metastasis, β-catenin levels control tumor differentiation and regulate both MAPK/Erk and PI3K/Akt signaling. Highly metastatic tumors with β-catenin stabilization are very similar to a subset of human melanomas. Together these findings establish Wnt signaling as a metastasis regulator in melanoma.

Metastasis accounts for the vast majority of morbidity and mortality associated with melanoma. Evidence suggests melanoma has a predilection for metastasis to particular organs. Experimental analyses have begun to shed light on the mechanisms regulating melanoma metastasis and organ specificity, but these analyses are complicated by observations of metastatic dormancy and dissemination of melanocytes that are not yet fully malignant. Additionally, tumor extrinsic factors in the microenvironment, both at the site of the primary tumor and the site of metastasis, play important roles in mediating the metastatic process. As metastasis research moves forward, paradigms explaining melanoma metastasis as a step-wise process must also reflect the temporal complexity and heterogeneity in progression of this disease. Genetic drivers of melanoma as well as extrinsic regulators of disease spread, particularly those that mediate metastasis to specific organs, must also be incorporated into newer models of melanoma metastasis.

Disseminated superficial actinic porokeratosis (DSAP) is an inherited disorder of keratinization readily diagnosed through clinical and histologic examination. While generally benign in nature, the lesions can have profound psychosocial implications for patients. Although no cure exists, a number of treatment modalities, from topical medications to laser and light devices, have been reported with variable success. The authors report two cases of DSAP treated with the 1927-nm thulium fiber fractional laser along with a review of the treatment literature for DSAP. This therapy is convenient and safe with nearly no downtime or morbidity associated with pigment or textural changes.

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