PMC6476061_01
Kaposiform hemangioendothelioma histology. A scanning low-power view shows a lobulated to infiltrative vascular tumor involving small bowel mesentery, serosa, muscularis propria, and submucosa. Tumor is visible as areas of dark blue to purple vascular tissue associated with lighter pink regions of fibrosis.
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Microscopic examination showed a lobulated to infiltrative vascular neoplasm involving adipose tissue, serosa, muscularis propria, and submucosa (Figure 1).
Kaposiform hemangioendothelioma histology. (a) The tumor demonstrates clusters of small capillary-sized vessels containing red blood cells, similar to capillary hemangioma. (b) Adjacent to these vascular nodules are scattered ectatic, irregularly shaped vascular channels (asterisks) with a lymphangioma-like morphology. (c) Interspersed throughout the tumor are more cellular regions composed of spindle cells reminiscent of Kaposi sarcoma but without significant cytologic atypia, mitotic activity, or necrosis. (d) The tumor is punctuated by glomeruloid structures, present as rounded nodules of dense vascular tissue associated with red blood cell fragments, hyaline droplets, and finely granular hemosiderin.
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The neoplasm was characterized by variable morphology, composed of nodules of small capillaries containing red blood cells and resembling capillary hemangioma (Figure 2(a)) interspersed with ectatic, irregularly shaped vascular channels resembling lymphangioma (Figure 2(b)). Interspersed throughout the tumor were cellular regions composed of loose fascicles of spindle cells associated with extravasated red blood cells and slit-like vascular spaces, reminiscent of Kaposi sarcoma (Figure 2(c)). Punctuated throughout the tumor were scattered glomeruloid structures, present as rounded nodules of vessels associated with red blood cell fragments, hyaline droplets, and finely granular hemosiderin deposition (Figure 2(d)), characteristic of KHE.
Kaposiform hemangioendothelioma immunohistochemistry. An immunohistochemical stain for D2-40 highlights the endothelial tumor cells throughout the lesion, including in the capillary hemangioma-like areas (a) as well as the more cellular Kaposi sarcoma-like regions (b).
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D2-40 (podoplanin), a lymphatic endothelial marker, highlighted cells in both capillary hemangioma-like areas and spindle cells areas (Figure 3).