Figure 2

Microscopic examination of the first biopsy specimen. (A) The first small biopsy specimen (H&E stains, inset) revealed an ill-defined lesion predominantly composed of a proliferation of irregular and sometimes anastomosing vascular structures containing no red blood cells mostly in the middle to lower layer of edematous dermis. Few lesions involve the superficial dermis, and extension into the subcutaneous fat was absent (inset). The covering epidermis exhibited mild acanthosis and modestly elongated thickened rete ridge without any evidence of atypical changes (H&E stains). Bars =1 mm. (B) On high-power view (H & E stains), these vascular channels were lined by modestly atypical endothelial cells having mildly hyperchromatic and pleomorphic nuclei, but no apparent mitotic figures. As the lesion grew within deeper dermis, these proliferating vascular channels dissected dermal collagenous bundles, occasionally arranged in low-papillary projections (inset) and/or characteristic hobnail or multi-layered cytomorphology (inset). Surrounding lymphocytic infiltrate was not evident. Bar = 200 μm.