Rheumatoid nodule
Encyclopedia
A rheumatoid nodule
is a local swelling or tissue lump, usually rather firm to touch, like an unripe fruit, which occurs almost exclusively in association with rheumatoid arthritis
. Very rarely rheumatoid nodules occur as 'rheumatoid nodulosis
' in the absence of arthritis. They are usually subcutaneous
especially over bony prominences such as the tip of the elbow or olecranon
or over the finger knuckles. Less commonly they occur in the lining of the lung and other internal organs. The occurrence of nodules in the lung of miners exposed to silica dust was known as Caplan's syndrome. Nodules vary in size from that of a lentil or pea to that of a mandarin orange. Quite often they are associated with synovial pockets or bursae. About 5% of rheumatoid arthritis
patients have such nodules within 2 years of disease onset, and the cumulative prevalence
is about 25%. In the great majority of cases nodules are not painful or disabling in any way, being more of an unsightly nuisance, but in some cases they can be painful, especially if the overlying skin breaks down. Rarely, the nodules occur at diverse sites on body (e.g. upper eyelid, distal region of soles, vulva and internally in the gallbladder, lung, heart valves, larynx and spine).
. Pea sized nodules have one centre. Larger nodules tend to be multilocular, with many separate shells or with connections between the necrotic centres. Individual necrotic centres may contain a cleft or several centres of necrosis may all open on to a large bursal pocket containing synovial fluid. The boundary between the necrotic centre and the outer fibrous shell is made up of the characteristic feature of the nodule, which is known as a cellular palisade. The palisade is a densely packed layer of macrophages and fibroblasts which tend to be arranged radially, like the seeds of a kiwi fruit or fig. Further out into the fibrous shell there is a zone that contains T lymphocytes and plasma cells in association with blood vessels. The overall histological picture is essentially identical to that of rheumatoid synovitis with the main differences being that the palisade replaces the synovial intima (they may blend imperciptibly in bursae) and an almost total absence of B lymphocytes.
Nodule (medicine)
For use of the term nodule in dermatology, see Nodule In medicine, a nodule refers to a relatively hard, roughly spherical abnormal structure....
is a local swelling or tissue lump, usually rather firm to touch, like an unripe fruit, which occurs almost exclusively in association with rheumatoid arthritis
Rheumatoid arthritis
Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...
. Very rarely rheumatoid nodules occur as 'rheumatoid nodulosis
Rheumatoid nodulosis
Rheumatoid nodulosis is a cutaneous condition associated with rheumatoid arthritis, characterized by the appearance of multiple nodules, most often on the hands.- See also :...
' in the absence of arthritis. They are usually subcutaneous
Subcutaneous tissue
The hypodermis, also called the hypoderm, subcutaneous tissue, or superficial fascia is the lowermost layer of the integumentary system in vertebrates. Types of cells that are found in the hypodermis are fibroblasts, adipose cells, and macrophages...
especially over bony prominences such as the tip of the elbow or olecranon
Olecranon
The olecranon is a large, thick, curved bony eminence of the forearm that projects behind the elbow.It is situated at the upper end of the ulna, one of the two bones in the forearm...
or over the finger knuckles. Less commonly they occur in the lining of the lung and other internal organs. The occurrence of nodules in the lung of miners exposed to silica dust was known as Caplan's syndrome. Nodules vary in size from that of a lentil or pea to that of a mandarin orange. Quite often they are associated with synovial pockets or bursae. About 5% of rheumatoid arthritis
Rheumatoid arthritis
Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...
patients have such nodules within 2 years of disease onset, and the cumulative prevalence
Prevalence
In epidemiology, the prevalence of a health-related state in a statistical population is defined as the total number of cases of the risk factor in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population...
is about 25%. In the great majority of cases nodules are not painful or disabling in any way, being more of an unsightly nuisance, but in some cases they can be painful, especially if the overlying skin breaks down. Rarely, the nodules occur at diverse sites on body (e.g. upper eyelid, distal region of soles, vulva and internally in the gallbladder, lung, heart valves, larynx and spine).
Diagnosis
Histological examination of nodules shows that they consist of a shell of fibrous tissue surrounding a center of fibrinoid necrosisFibrinoid necrosis
Fibrinoid necrosis is a form of necrosis, or tissue death, in which there is accumulation of amorphous, basic, proteinaceous material in the tissue matrix with a staining pattern reminiscent of fibrin. It is associated with conditions such as immune vasculitis Fibrinoid necrosis is a form of...
. Pea sized nodules have one centre. Larger nodules tend to be multilocular, with many separate shells or with connections between the necrotic centres. Individual necrotic centres may contain a cleft or several centres of necrosis may all open on to a large bursal pocket containing synovial fluid. The boundary between the necrotic centre and the outer fibrous shell is made up of the characteristic feature of the nodule, which is known as a cellular palisade. The palisade is a densely packed layer of macrophages and fibroblasts which tend to be arranged radially, like the seeds of a kiwi fruit or fig. Further out into the fibrous shell there is a zone that contains T lymphocytes and plasma cells in association with blood vessels. The overall histological picture is essentially identical to that of rheumatoid synovitis with the main differences being that the palisade replaces the synovial intima (they may blend imperciptibly in bursae) and an almost total absence of B lymphocytes.