I have recently encountered a case of lentigo maligna melanoma associated with basaloid-looking dermal component. Immunohistochemical stains showed keratin and melanocytic marker expression in the dermal component.
This case raised a critical differential diagnosis of a rare keratin-positive melanoma, collision tumor, a tumor with divergent melanocytic and epithelial differentiation. and melanoma colonizing basal cell carcinoma.
The tumors composed of malignant epithelial and melanocytic populations were recently reviewedind depth by Dr. Satter et al. Similar 2 cases were recently described by Dr. Rodriguez et al. under the name of malignant basomelanocytic tumors.
Dr. Rosai discussed basomelanocytic tumors during his recent lecture at USCAP 2009 postulating that their existence may be interpreted against neurocrestic origin of melanocytes.
The purpose of this project is to collect a large series of similar cases and advance understanding of these rare lesions.