A rheumatoid nodule is a lump of tissue, or an area of swelling, that appear on the exterior of the skin usually around the olecranon (tip of the elbow) or the interphalangeal joints (finger knuckles), but can appear in other areas. There are four different types of rheumatoid nodules: subcutaneous rheumatoid nodules, cardiac nodules, pulmonary nodules, and central nervous systems nodules. These nodules occur almost exclusively in association with rheumatoid arthritis. Very rarely do rheumatoid nodules occur as rheumatoid nodulosis (multiple nodules on the hands or other areas) in the absence of rheumatoid arthritis. Rheumatoid nodules can also appear in other areas of the body other than the skin. Less commonly they occur in the lining of the lung or other internal organs. The occurrence of nodules in the lung of miners exposed to silica dust was known as Caplan’s syndrome. Rarely, the nodules occur at diverse sites on body (e.g. upper eyelid, distal region of the soles of the feet, vulva and internally in the gallbladder, lung, heart valves, larynx, and spine).Rheumatoid nodules can vary in size from 2 mm to 5 cm and are usually rather firm to the touch. Quite often they are associated with synovial pockets or bursae. About 5% of people with rheumatoid arthritis have such nodules within two years of disease onset, and the cumulative prevalence is about 20 to 30%. Risk factors of developing rheumatoid nodules include as smoking and trauma to small vessels.In the majority of the time, nodules are not painful or disabling in any way.
Parapsoriasis refers to one of a group of skin disorders that are characterized primarily by their resemblance to psoriasis (red, scaly lesions), rather than by their underlying cause. Neoplasms can develop from parapsoriasis. For example, it can develop into cutaneous T-cell lymphoma. The word "parapsoriasis" was formed in 1902. Classification
The parapsoriasis groups, described and debated for nearly a century, has spawned a confusing nomenclature. There are some authors who prefer to limit the term "parapsoriasis" to large- and small-plaque variants only. However, the following classification scheme is now generally accepted:: 450 
Large-plaque parapsoriasis
Small-plaque parapsoriasis
Pityriasis lichenoides
Pityriasis lichenoides chronica
Pityriasis lichenoides et varioliformis acuta
Lymphomatoid papulosis

See also
Poikiloderma vasculare atrophicans
List of cutaneous conditions

References


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