Feltys syndrome (FS), also called Felty syndrome, is rare autoimmune disease characterized by the triad of rheumatoid arthritis, enlargement of the spleen and low neutrophil count. The condition is more common in those aged 50–70 years, specifically more prevalent in females than males, and more so in Caucasians than those of African descent. It is a deforming disease that causes many complications for the individual. Signs and symptoms
The symptoms of Feltys syndrome are similar to those of rheumatoid arthritis. Affected individuals have painful, stiff, and swollen joints, most commonly in the joints of the hands, feet, and arms. In some affected individuals, Feltys syndrome may develop during a period when the symptoms and physical findings associated with rheumatoid arthritis have subsided or are not present; in this case, Feltys syndrome may remain undiagnosed. In more rare instances, the development of Feltys syndrome may precede the development of the symptoms and physical findings associated with rheumatoid arthritis.Feltys syndrome is also characterized by an abnormally enlarged spleen (splenomegaly) and abnormally low levels of certain white blood cells (neutropenia). As a result of neutropenia, affected individuals are increasingly susceptible to certain infections. Keratoconjunctivitis sicca may occur due to secondary Sjögrens syndrome. Individuals with Feltys syndrome may also experience fever, weight loss, and/or fatigue. In some cases, affected individuals may have discoloration (abnormal brown pigmentation) of the skin, particularly of the leg, sores (ulcers) on the lower leg, and/or an abnormally large liver (hepatomegaly).
The spleen is an important lymphatic organ that is involved in filtration of the blood by discarding old and damaged red blood cells as well as maintaining platelet levels. The spleen is a lymphatic organ, which means it is largely involved in the immune system and immune responses. When the spleen becomes enlarged, it is a strong sign of infection somewhere in the body and can be caused by inflammatory conditions such as rheumatoid arthritis. The increased need for production assistance of white blood cells to affected areas causes hyperfunction of the spleen. This increase in defense activities ultimately causes hypertrophy of the spleen, leading to splenomegaly. The spleen is found in the left upper quadrant (LUQ) of the peritoneal cavity and due to its enlargement, can cause stress on neighboring organs. Diagnosis
This condition affects less than 1% of patients with rheumatoid arthritis. The presence of three conditions: rheumatoid arthritis, an enlarged spleen (splenomegaly), and an abnormally low white blood cell count are indications that Feltys syndrome is possibly occurring. This condition as a whole is difficult to diagnose due to its complexity given a combination of disorders. It is commonly overlooked or misdiagnosed as other conditions (e.g., leukemia, systemic lupus erythrematosus) because of the rarity and lack of good understanding about it. An acronym can be used to make recognizing this disease somewhat easier:S: SplenomegalyA: AnemiaN: NeutropeniaT: ThrombocytopeniaA: Arthritis (rheumatoid)

Conditions of the blood
A complete blood count (CBC) can be done to diagnose anemia (normochromic, normocytic), thrombocytopenia, and neutropenia.