Please answer the following question: Information:  - Gangrene (or gangrenous necrosis) is a type of necrosis caused by a critically insufficient blood supply. This potentially life-threatening condition may occur after an injury or infection, or in people suffering from any chronic health problem affecting blood circulation. The primary cause of gangrene is reduced blood supply to the affected tissues, which results in cell death. Diabetes and long-term smoking increase the risk of suffering from gangrene.  - Bleeding, also known as hemorrhaging or haemorrhaging, is blood escaping from the circulatory system. Bleeding can occur internally, where blood leaks from blood vessels inside the body, or externally, either through a natural opening such as the mouth, nose, ear, urethra, vagina or anus, or through a break in the skin. Hypovolemia is a massive decrease in blood volume, and death by excessive loss of blood is referred to as exsanguination. Typically, a healthy person can endure a loss of 1015% of the total blood volume without serious medical difficulties (by comparison, blood donation typically takes 810% of the donor's blood volume). The stopping or controlling of bleeding is called hemostasis and is an important part of both first aid and surgery.  - Rheumatoid vasculitis is skin condition that is a typical feature of rheumatoid arthritis , presenting as peripheral vascular lesions that are localized purpura , cutaneous ulceration , and gangrene of the distal parts of the extremities .  - Purpura is a condition of red or purple discolored spots on the skin that do not blanch on applying pressure. The spots are caused by bleeding underneath the skin usually secondary to vasculitis or dietary deficiency of vitamin C (scurvy). They measure 0.31 cm (310 mm), whereas petechiae measure less than 3 mm, and ecchymoses greater than 1 cm.  - Fibromyalgia (FM) is a medical condition characterised by chronic widespread pain and a heightened pain response to pressure. Other symptoms include feeling tired to a degree that normal activities are affected, sleep problems, and troubles with memory. Some people also report restless legs syndrome, bowel or bladder problems, numbness and tingling, and sensitivity to noise, lights or temperature. Fibromyalgia is frequently associated with depression, anxiety, and posttraumatic stress disorder. Other types of chronic pain are also frequently present. The cause of fibromyalgia is unknown; however, it is believed to involve a combination of genetic and environmental factors with half the risk attributed to each. The condition runs in families and many genes are believed to be involved. Environmental factors may include psychological stress, trauma, and certain infections. The pain appears to result from processes in the central nervous system and the condition is referred to as a "central sensitization syndrome". Fibromyalgia is recognized as a disorder by the US National Institutes of Health and the American College of Rheumatology. There is no specific diagnostic test. Diagnosis involves first ruling out other potential causes and verifying that a set number of symptoms are present. The treatment of fibromyalgia can be difficult. Recommendations often include getting enough sleep, exercising regularly, and eating a healthy diet. Cognitive behavioral therapy may also be helpful. The medications duloxetine, milnacipran, or pregabalin may be used. Use of opioid pain medication is controversial with some stating their use is poorly supported by evidence and others saying that weak opioids may be reasonable if other medications are not effective. Dietary supplements also lack evidence to support their use. While fibromyalgia can last a long time, it does not result in death or tissue damage. Fibromyalgia is estimated to affect 28% of the population. Females are affected about twice as often as males. Rates appear...  - Scurvy is a disease resulting from a lack of vitamin C. Early symptoms include weakness, feeling tired, curly hair, and sore arms and legs. Without treatment, decreased red blood cells, gum disease, and bleeding from the skin may occur. As scurvy worsens there can be poor wound healing, personality changes, and finally death from infection or bleeding. Scurvy is caused by not enough vitamin C in the diet. It typically takes at least a month of little to no vitamin C before symptoms occur. In modern times, it occurs most commonly in people with mental disorders, unusual eating habits, alcoholism, and old people who live alone. Other risk factors include intestinal malabsorption and dialysis. Humans and certain other animals require vitamin C in their diets to make the building blocks for collagen. Diagnosis is typically based on physical signs, X-rays, and improvement after treatment. Treatment is with vitamin C supplements taken by mouth. Improvement often begins in a few days with complete recovery in a few weeks. Sources of vitamin C in the diet include citrus fruit and a number of vegetables such as tomatoes and potatoes. Cooking often decreases vitamin C in foods. Scurvy is currently rare. It occurs more often in the developing world in association with malnutrition. Rates among refugees are reported at 5% to 45%. Scurvy was described as early as the time of ancient Egypt. It was a limiting factor in long distance sea travel, often killing large numbers of people. A Scottish surgeon in the Royal Navy, James Lind, was the first to prove it could be treated with citrus fruit in a 1753 publication. His experiments represented the first controlled trial. It took another 40 years before the British Navy began giving out lemon juice routinely.  - Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involved, with the same joints typically involved on both sides of the body. The disease may also affect other parts of the body. This may result in a low red blood cell count, inflammation around the lungs, and inflammation around the heart. Fever and low energy may also be present. Often, symptoms come on gradually over weeks to months. While the cause of rheumatoid arthritis is not clear, it is believed to involve a combination of genetic and environmental factors. The underlying mechanism involves the body's immune system attacking the joints. This results in inflammation and thickening of the joint capsule. It also affects the underlying bone and cartilage. The diagnosis is made mostly on the basis of a person's signs and symptoms. X-rays and laboratory testing may support a diagnosis or exclude other diseases with similar symptoms. Other diseases that may present similarly include systemic lupus erythematosus, psoriatic arthritis, and fibromyalgia among others. The goal of treatment is to reduce pain, decrease inflammation, and improve a person's overall functioning. This may be helped by balancing rest and exercise, the use of splints and braces, or the use of assistive devices. Pain medications, steroids, and NSAIDs are frequently used to help with symptoms. A group of medications called disease-modifying antirheumatic drugs (DMARDs), such as hydroxychloroquine and methotrexate, may be used to try to slow the progression of disease. Biological DMARDs may be used when disease does not respond to other treatments. However, they may have a greater rate of adverse effects. Surgery to repair, replace, or fuse joints may help in certain situations. Most alternative medicine treatments are not supported by evidence. RA affects between 0.5 and 1% of adults in the developed...  - Infection is the invasion of an organism's body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to these organisms and the toxins they produce. Infectious disease, also known as transmissible disease or communicable disease, is illness resulting from an infection. Infections are caused by infectious agents including viruses, viroids, prions, bacteria, nematodes such as parasitic roundworms and pinworms, arthropods such as ticks, mites, fleas, and lice, fungi such as ringworm, and other macroparasites such as tapeworms and other helminths.    Given the paragraphs above, decide what entity has the relation 'medical specialty' with 'rheumatology'.
Answer:
rheumatoid vasculitis