[Expression of galanin in melanocytic tumors]

Galanin is a neuropeptide with wide-ranging effects, especially within the endocrine and nervous systems. Galanin and its receptors are present in human skin. Galanin is expressed in different neural, endocrine and neuroendocrine tumors and, on the other hand, several neuropeptides, particularly alpha-MSH, seem to play a role in the pathogenesis of melanoma.

To investigate the expression of galanin in cutaneous melanomas and melanocytic nevi and correlate it with alpha-MSH expression and several prognostic factors for melanoma.

We performed an observational and retrospective study of the immunohistochemical expression of galanin and alpha-MSH in samples of cutaneous melanomas diagnosed in the last 5 years in the San Jorge Hospital, Huesca (Spain). Different types of melanocytic nevi were also analyzed.

A total of 130 pigmented lesions were studied: 38 primary cutaneous melanomas, 6 cutaneous melanoma metastases and 86 melanocytic nevi. Immunostaining with galanin and alpha-MSH was significantly higher in melanomas than in melanocytic nevi (p < 0.001), although spindle cell and blue nevi showed significant expression of alpha-MSH. More than 50 % of nodular melanomas and 90 % of superficial spreading melanomas were positive for galanin and alpha-MSH, and the latter also showed the highest percentage of positive cells for galanin (mean 35.09 +/- 28.16) as well as for alpha-MSH (mean 67.64% +/- 35.38). A positive correlation of 71 % was found for immunostaining of both neuropeptides in melanomas. No significant correlation was observed between galanin expression and age, gender, location of the lesions, Breslow index, Clark level and mitotic index.

Our study shows the expression of galanin in cutaneous melanoma and its significant correlation with alpha-MSH immunostaining.