Abstract 381: Non-invasive histology for early detection of cutaneous melanoma and pigmented lesions in vivo

Abstract

Listen

Translate article

Abstract Rationale The diagnosis of melanoma is based on clinical identification followed by histopathologic confirmation. Surgical excision remains the mainstay for a suspicious lesion that will be evaluated for the morphological and cytological signatures of melanomas. However, in some patients such as those with atypical mole syndrome, multiple biopsies of each lesion can be burdensome. We have previously reported that imaging the distribution of eumelanin and pheomelanin can be used to detect melanomas from benign lesions (Matthews TE et al. Sci Transl Med Feb 23;3(71)). In this pre-clinical study we extend our investigation in vivo using nonlinear pump-probe microscopy. We assess cellular morphology and detect the expression of eumelanin and pheomelanin, the two forms of melanin found in skin as markers of melanoma progression. Methods Two melanoma cells lines (A2058; SK-MEL-28) were incubated in human skin dermis. Grafts were xenotransplanted onto SCID mice (n=13, A2058; n=6, SK-MEL-28; n=2 control) and imaged every 8-10-days for cancer progression and morphological changes. Pump-probe microscopy was performed concurrently with two other established laser scanning microscopy methods, multiphoton autofluorescence (MPAF) and reflectance confocal scanning laser microscopy (RCSLM). After 4-8 weeks the subjects were euthanized and the tumor excised for histological examination. Hematoxylin and eosin staining was performed to confirm the presence of the tumor and to correlate with the morphological findings after laser image acquisition. Results The in vivo pump-probe images of the cancer subjects showed an irregular distribution of the pigment, lacking the organized structure typical of skin. Pump-probe images of both melanoma cell lines indicated pigmentation that was either primarily eumelanin or a mixture of eumelanin and pheomelanin with marked spatial heterogeneity. Pigmentation was observed in the two control mice but localized on the basal cells with a well-organized cellular architecture. At the end of the cancer subjects’ life the histological examination showed atypical melanocytes mainly present as single cells in the dermal area. Hyperplasia was also present in the dermal compartment and in the dermal-epidermal junction of the skin. Conclusions The present work may open new avenues for the non-invasive detection of cellular and pigment lesions to prevent melanoma development and invasiveness. Such method can play a role in the diagnosis of melanoma in those patients with multiple lesions or in the areas of the body where the lesion is very exposed such as the face or neck and in ocular region. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 381. doi:1538-7445.AM2012-381