Noninvasive imaging of melanoma with reflectance mode confocal scanning laser microscopy in a murine model.

A reflectance-mode confocal scanning laser microscope (rCSLM) was developed for imaging early-stage melanoma in a living mouse model without the addition of exogenous contrast agents. Lesions were first located by surveying the dorsum with a polarized light camera, then imaged with the rCSLM. The images demonstrated two characteristics of melanoma in this animal model: (1) melanocytes and apparent tumor nests in the epidermis at the stratum spinosum in a state of pagetoid spread and (2) architectural disruption of the dermal-epidermal junction. The epidermal melanocytes and apparent tumor nests had a high melanin content, which caused their reflectance to be fivefold greater than the surrounding epidermis. The rCSLM images illustrate the difference between normal skin and sites with apparent melanoma. This imaging modality shows promise to track the progression of melanoma lesions in animal models.