case_images: PMC11755473_01
case_images: (A) Histopathological photomicrograph showing the neoplastic lesion constituted by two different components (hematoxylin-eosin, original magnification 4x), scale bar 1 mm. (B) Higher magnification showing melanocytic component with melanin pigment and squamous component (hematoxylin-eosin, Original Magnification 10x), scale bar 250 microm. (C,D) The neoplastic population is made up of sheets of melanoma cells intermingled with islands of squamous cells showing central horn pearl formations and focal clear cell changes. Melanin pigment deposition is observed throughout the lesion (hematoxylin-eosin, original magnification 10x), scale bar 250 microm.
case_images: dermatopathology-12-00001-g001.jpg
case_images: PMC11755473_01_dermatopathology-12-00001-g001.jpg
case_images: dermatopathology-12-00001-f001
case_images: Cytologically, it was made up of two phenotypically distinct populations, intimately intermingled together and almost blending into each other at several points (Figure 1).
case_images: Immunohistochemistry confirmed the dual nature of neoplastic population: squamous cells were positive for CK-AE1/AE3, instead melanocytes expressed Melan-A. p53 showed strong nuclear positivity in melanocytes, suggesting an underlying mutation. Also, PRAME was strongly positive in the melanocytic component (immunohistochemistry, original magnification 10x and 5x), scale bar 250 microm (A-C) and 500 microm (D).
case_images: dermatopathology-12-00001-g002.jpg
case_images: PMC11755473_01_dermatopathology-12-00001-g002.jpg
case_images: dermatopathology-12-00001-f002
case_images: Immunohistochemistry showed a dichotomous pattern (Figure 2): squamous cells expressed CK-AE1/AE3 while the melanocytic component was positive for Melan-A and PRAME. p53 showed a strong nuclear expression in melanoma cells, suggesting an underlying mutation.