On MRI, IHs show a well-circumscribed lesion with intermediate and increased signal intensity on T1- and T2-weighted sequences, respectively, and strong enhancement after gadolinium injections, with fast-flow vessels. Tissue for diagnosis can be obtained via fine-needle aspiration, skin biopsy, or excisional biopsy. Under the microscope, IHs are unencapsulated aggregates of closely packed, thin-walled capillaries, usually with endothelial lining. Blood-filled vessels are separated by scant connective tissue. Their lumina may be thrombosed and organized. Hemosiderin pigment deposition due to vessel rupture may be observed. The GLUT-1 histochemical marker can be helpful in distinguishing IHs from other items on the differential diagnosis, such as vascular malformations. Liver
Infantile haemangiomas in the liver are found in 16% of all liver haemangiomas. Its sizes are usually less than 1 to 2 cm in diameter. It may show a "flash-filling" phenomenon in which there is the fast enhancement of the contrast material in the lesion instead of slow, centripetal, nodular filling of the lesions in usual hemangiomas. On CT and MRI, it shows rapid filling during arterial phase, with contrast retention in venous and delayed phases. Treatment
Most IHs disappear without treatment, leaving minimal to no visible marks. This may take many years, however, and a proportion of lesions may require some form of therapy. Multidisciplinary clinical practice guidelines for the management of infantile hemangiomas were recently published. Indications for treatment include functional impairment (i.e. visual or feeding compromise), bleeding, potentially life-threatening complications (airway, cardiac, or hepatic disease), and risk of long-term or permanent disfigurement.
Dermatographic urticaria is a skin disorder and one of the most common types of urticaria, affecting 2–5% of the population. Signs and symptoms
The condition manifests as an allergic-like reaction, causing a warm red wheal to appear on the skin. As it is often the result of scratches, involving contact with other materials, it can be confused with an allergic reaction, when in fact it is the act of being scratched that causes a wheal to appear. These wheals are a subset of urticaria (hives), and appear within minutes, in some cases accompanied by itching. The first outbreak of urticaria can lead to other reactions on body parts not directly stimulated, scraped, or scratched. In a normal case, the swelling will decrease without treatment within 15–30 minutes, but, in extreme cases, itchy red welts may last anywhere from a few hours to days. Causes
Symptoms are thought to be the result of histamine being released by mast cells on the surface of the skin. Despite the lack of antigens, histamine causes the skin to swell in affected areas. If the membrane that surrounds the mast cells is too weak it will easily and rapidly break down under physical pressure, which then causes an allergic-like reaction.Symptoms can be caused or induced by:

The underlying cause of dermographism is not known, and it can last for many years without relief. The condition may subside and be effectively cured; however, it is often a lifelong ailment.