The word "arthritis" refers to any number of conditions that result in joint inflammation. People often think of arthritis as a wear-and-tear disease of old age, but there are other, more rare types of arthritis. In fact, there are more than 100 forms of arthritic conditions, according to the Centers for Disease Control and Prevention. Causes may be genetic, infectious or of unknown origin.
Adult Onset Still's Disease
Adult onset Still's disease is a form of arthritis diagnosed in fewer than one in 100,000 people annually, reports MedlinePlus.com. It is more common in women and is systemic in nature, affecting not only the joints, but other tissues and organs as well. Symptoms include fever, joint pain and swelling, with a pink rash that accompanies the fever. People may have an inflammation of the lining of the lungs, which leads to pain upon deep breathing. The lining of the heart can also become inflamed. Swollen lymph nodes, a sore throat and weight loss may also occur. Adult onset Still's disease can become chronic, resulting in a permanent arthritic condition.
Palindromic Rheumatism
The Johns Hopkins Arthritis Center describes palindromic rheumatism as a very rare disease that is often mistaken for rheumatoid arthritis. The condition is marked by a sudden onset, with short episodes of intense joint pain, inflammation and swelling. These attacks last from hours to several days, and then disappear. The symptoms tend to move around, affecting different joints with each flare up. The skin around the affected joint may become red and inflamed. Once the inflammation subsides, there are no residual effects and no damage to the affected joints. Even though palindromic rheumatism is not the same as rheumatoid arthritis, it does eventually develop into rheumatoid arthritis in up to half of all patients.
Mycotic Arthritis
Mycotic, or fungal, arthritis, is a very rare illness caused by a fungal infection in or around a joint. Symptoms usually occur in the larger, weight-bearing joints, and include inflammation, swelling, pain and stiffness. This condition is more likely to happen in a person whose immune system is compromised. Sometimes mycotic arthritis occurs because of a fungal infection somewhere else in the body. Causative fungal organisms include Mycobacteria, Blastomyces, Histoplasma, Candida, Aspergillus, Cryptococcus and Coccidioides, according to Merck Manuals Medical Library.
