Lipoblast-Like Morphology in a Uveal Melanoma with Delayed Metastasis to the Liver.

Uveal melanomas are typically described as having epithelial or spindled cell morphology; however, as is the nature of melanomas, the morphology of the malignant melanocytes can be varied. We describe a unique case of metastatic uveal melanoma with lipoblast-like morphology, identified in the liver during an autopsy of a 75-year-old woman. Apart from a remote history of uveal melanoma in the right eye, there was no other history of cancer, and there were no concerning skin lesions present. The liver exhibited hepatomegaly with diffuse and extensive involvement of malignant tumor cells. Histopathological evaluation of liver sections showed malignant epithelioid and spindle cell proliferation. A distinct, spiculated, tan-white area revealed sheets of malignant cells with small and large vacuoles within the cytoplasm and scalloped nuclei, mimicking lipoblasts and adipocytes. Immunohistochemical stains confirmed these cells to be malignant melanoma cells. Being aware of this morphology in uveal melanomas is important especially when there is metastasis to the liver, so that it is not mistaken for more benign processes such as steatosis.