Figure 1

General characteristics of lobular capillary hemangioma (LCH). (A) Several lobules are observed in the lesion (lobular pattern). (B) In a lobule, presence of a branched venule (v) and numerous capillary-sized vessels, showing ECs (brown) and pericytes (red). (C) A zone with sinusoidal hemangioma-like morphology is observed, presenting wide vascular spaces with pillars, some of which are arranged in a linear fashion, forming incomplete septa (arrows). (D) An IPEH-like zone with numerous pillars irregularly arranged(arrows) in a wide vascular space. (E) CD34⁺ ECs (brown) and αSMA⁺ smooth muscle cells (red) are observed in the vessel walls. A large (arrowhead) and small pillars (arrows) are present. (F) Zone of ulceration with capillary-sized vessels, fibrin deposits and inflammatory infiltrate. (G) Sprouts are observed from a mother vessel (outward growth - arrows). In one of them, note a tip EC growing toward the interstitium (arrowhead). In the insert, the collagen IV stained basal membrane disappears in a tip EC (arrowhead). (H) Stalk ECs from a mother vessel are observed initiating a loop (arrows). In the insert, stalk ECs expressing ki67 in a loop are observed (arrows). (A to E,G,H) Double-staining with anti-CD34 (brown) and anti-αSMA (red). (F) H&E staining. Bar: (A,C) 160 µm; (B,F) 25 µm; (D,E,G,H) 20 µm.