|Clinical Diagnosis:||Non-melanoma skin cancer, pyogenic granuloma, amelanotic melanoma|
The specimen consists of a shave biopsy of skin in which the rete architecture of the epidermis is effaced and the underlying dermis contains spindled cells dispersed among sclerotic collagen bundles and dilated lymphovascular spaces. A patchy lymphocytic infiltrate is present along the dermoepidermal junction. A junctional melanocytic proliferation is not evident.
The differential diagnosis was scar versus desmoplastic melanoma versus other.
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View the Myriad myPath Melanoma Score and Final Diagnosis
Myriad myPath® Melanoma Score
The Myriad myPath Melanoma score of +3.8 indicated the gene expression signature of this lesion is more like that of a malignant melanoma than a benign nevus.
Despite the lack of an in situ melanoma component and the striking resemblance to a scar overall, the positive score prompted treatment of the lesion as likely desmoplastic melanoma.
The re-excision specimen demonstrated clear-cut evidence of desmoplastic melanoma, including an expansile nodule of spindled cells, some with obvious cytologic atypia, and focally within one fragment an in situ melanoma component not present on the initial biopsy.
Immunohistochemical studies demonstrated that a proportion of the dermal spindled cells expressed S100 and Sox10 but lacked expression of HMB45 and Melan-A, consistent with the diagnosis of desmoplastic melanoma.