Abstract

A 66-year-old male with no prior history of melanoma presented with gray-black hyperpigmented patches on the right temple and right jaw line. H&E of two punch biopsies revealed large rounded neoplastic cells with cytoplasmic melanin pigment within vascular lumens. The intravascular cells had large nuclear-to-cytoplasmic ratios, large nuclei and prominent nucleoli. Immunostaining demonstrated that the cells were positive for Melan-A, S100 protein, Sox 10, PRAME, and VE1( BRAF V600E mutation). The endothelial cells lining the affected vascular spaces were CD34 and D2-40 positive. Dual Sox 10 / D2-40 immunostain confirmed the malignant melanoma cells were within lymphatics, and further documented lymphangitic spread of metastatic melanoma. Perivascular melanophages were prominent. There were no lymphocytes or macrophages admixed with the intralymphatic tumor cells. There are various reports of “angiotropic” melanoma. However, these reports describe melanoma cells migrating along the external walls of blood vessels. They do not describe intraluminal melanoma. There are reports about lymphatic invasion of primary melanoma correlating with increased risk of melanoma metastasis. Finally, there are reports of lymphangitic spread of melanoma to the lung. However, to our knowledge, lymphangitic metastatic melanoma reminiscent of cutaneous carcinomatosis has not been described. We have seen only a few other cases of lymphangitic spread of melanoma in our collective experience, and none that presented with macular hyperpigmentation of the skin. This patient is being treated with immune checkpoint blockers, but assessment of treatment response may be difficult due to the abundant melanophages in the perivascular tissues.

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