Predominant formation of heavily pigmented dermal melanocytomas resembling 'animal-type' melanomas in hepatocyte growth factor (C57BL/6 x C3H)F1 mice following neonatal UV irradiation.
BACKGROUND
Transgenic mice expressing hepatocyte growth factor (HGF) develop cutaneous melanocytic tumors following neonatal UV exposure. Here, we examined the histologic spectrum of UV-induced melanocytic tumors in HGF mice on a pigmented (C57BL/6 x C3H/HeN)F(1) background.


METHODS
Neonatally irradiated (4000 J/m(2)) mice were monitored for 43 weeks, and 31/34 (91%) animals developed a total of 163 melanocytic tumors.


RESULTS
Of 54 primary tumors analyzed, most (49/54, 91%) demonstrated exclusively dermal collections of epithelioid cells with voluminous densely pigmented cytoplasm. Seven of these also demonstrated a population of spindled cells with mitoses. Several (3/54, 6%) tumors exhibited a junctional component with melanocytes present in the epidermis. Staining with PEP8 confirmed the presence of interfollicular melanocytes at the dermal-epidermal junction in neonatal skin.


CONCLUSIONS
In contrast to HGF animals on an albino (FVB) background, HGF animals on the pigmented (C57BL/6 x C3H/HeN)F(1) background do not develop classic radial growth phase melanoma but rather predominantly develop dermal melanocytomas resembling the 'animal-type' melanoma occasionally seen in humans. These results demonstrate the influence of genetic background on histologic pattern of UV-induced melanomas in mice.
Florell
Scott R
SR
Department of Dermatology, University of Utah, Salt Lake City, UT 84132, USA. scott@derm.med.utah.edu
Thomas
Joshua
J
Grossman
Douglas
D
D000818:Animals; D000831:Animals, Newborn; D014408:Biomarkers, Tumor / Q000378:metabolism; D015622:Epithelioid Cells / Q000473:pathology / Q000528:radiation effects; D005260:Female; D005838:Genotype; D017228:Hepatocyte Growth Factor / Q000235:genetics*; D007124:Immunoenzyme Techniques; D008207:Lymphatic Metastasis; D008297:Male; D008544:Melanocytes / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D008546:Melanoma, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009381:Neoplasms, Radiation-Induced / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D012867:Skin / Q000528:radiation effects*; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D013045:Species Specificity; D014466:Ultraviolet Rays
D014408:Biomarkers, Tumor; D017228:Hepatocyte Growth Factor
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