Desmoplastic melanoma

(A) Low power light photomicrograph of a desmoplastic melanoma, showing a poorly circumscribed tumor with a marked, fibrogenic, stromal response. There is lentigo maligna overlying the dermal tumor (arrows).
(B) Higher power view light photomicrograph of a desmoplastic melanoma, showing that the malignant cells have hyperchromatic, elongated nuclei, resembling those of fibroblasts. The malignant spindle cells form long fascicles that dissect dermal collagen.