Skin biopsy of left medial leg in an 86 year-old male on Pembrolizumab for melanoma.
Case Discussion
Desmoplastic melanoma typically presents as an amelanotic lesion within sun-exposed areas and often resembles scar tissue. Histologically, the lesion is often ill-defined with atypical spindled cell melanocytes infiltrating the dermis. Overlying lentigo maligna and lymphoid aggregates may be seen. Neurotropism is also a common finding. Immunohistochemical staining typically shows S100 and SOX10 positivity, while HMB-45 is negative.
In this case, the biopsy demonstrates a subtle case of desmoplastic melanoma with scattered malignant cells between collagen bundles. Neurotropism is also seen.
SOX10 and S100 stains highlight malignant spindled cells infiltrating the dermis.
This slide shows H&E stain. See related content for SOX10 and S100 stains.
Pun, C., Sade, S. Skin, Desmoplastic melanoma, H&E stain. Digital Laboratory Medicine Library, Dept of Laboratory Medicine & Pathobiology, University of Toronto. Published
. Accessed December 17, 2025. https://dev.dlml.cflabs.ca/image/skin-desmoplastic-melanoma-he-stain-lmp40973
