Micrograph of a<unk>  sarcoma showing the characteristic spindle cells, high vascularity, and intracellular hyaline globs. H&E stain. Despite its name, in general it is not considered a true sarcoma, which is a tumor arising from mesenchymal tissue. The histogenesis of<unk>  remains controversial.<unk>  may arise as a cancer of lymphatic endothelium and forms vascular channels that fill with blood cells, giving the tumor its characteristic bruise-like appearance.<unk> HV proteins are uniformly detected in<unk>  cancer cells.<unk>  lesions contain tumor cells with a characteristic abnormal elongated shape, called spindle cells. The most typical feature of<unk>  sarcoma is the presence of spindle cells forming slits containing red blood cells. Mitotic activity is only moderate and pleomorphism is usually absent. The tumor is highly vascular, containing abnormally dense and irregular blood vessels, which leak red blood cells into the surrounding tissue and give the tumor its dark color. Inflammation around the tumor may produce swelling and pain. Variously sized PAS positive hyaline bodies are often seen in the cytoplasm or sometimes extracellularly. The spindle cells of<unk>  sarcoma differentiate toward endothelial cells, probably of lymph vessel rather than blood vessel origin. The consistent immunoreactivity for podoplanin supports the lymphatic nature of the lesion. File:Micrograph of promontory sign of<unk> .Micrograph of promontory sign in<unk>  in patch stage. Dilated irregular vascular channels surround a pre-existing vessel. File:Micrograph of plaque stage of<unk> .Micrograph of plaque stage, with bizarre vessels dissecting the upper dermis. There is erythrocyte extravasation and hemosiderin pigmentation. File:Micrograph of tumor stage of<unk> .Micrograph of tumor stage. Well-circumscribed spindle-cell tumor. Erythrocytes lie within poorly defined slit-like vascular spaces.
Kaposi's sarcoma
Melanoma
Mule spinners' cancer
Melanocytic nevus
Ewing's sarcoma
Blue rubber bleb nevus syndrome
Lymphangiosarcoma
Pyogenic granuloma