What Is Meant by Seronegative Arthritis?

I have just been diagnosed (after many years of nobody being able to tell me what was wrong) with "sero-negative arthritis." The "sero" comes from "serum," meaning that blood tests show up negative when tested for rheumatoid factor etc, yet I still experience flare ups where my right knee swells rather badly. The diagnosis was made on the basis of related skin disorders such as some acne, occasional dermatitis on the hands and dandruff combined with sensitivity to pressure on various places in my body (neck and back, feet and stomach area). I can't find any information on this type of arthritis anywhere, yet I was told that along with osteoarthritis, rheumatoid arthritis and gout it is one of the most common forms. Does it go by another name too?

There is a variety of forms of arthritis that are referred to as "sero-negative arthritis."  You are correct that this simply means that these forms of arthritis are not associated with the rheumatoid factor blood test.  Diseases that are referred to as sero-negative arthritis include psoriatic arthritis, ankylosing spondylitis, reactive arthritis, the arthritis of inflammatory bowel disease, and sero-negative rheumatoid arthritis. Of these, the first four are closely related to each other and reviewing information about these conditions may be of help to you.