[GOUTY TOPHUS]. The deposition of monosodium urate crystals in joints in patients with gout can lead to joint deformity and sometimes large periarticular cutaneous deposits. This image shows deposit of characteristic crystals in synovium and periarticular tissue of metatarsophalangeal joint in a patient with uncontrolled gout. Note the presence of crystal deposits surrounded by a scalloping of palisaded histiocytes. This appearance can be similar to rheumatoid arthritis.
[GOUTY TOPHUS]. Chronic tophaceous arthritis is the result of repetitive acute attacks of gout with slow but inexorable deposition of urate crystals. The deposits can occur in periarticular cartilage, synovium, and soft tissue. The tissue mounts a reaction to crystal deposition by an acute inflammatory cells infiltrate which gives rise to a chronic inflammatory cell infiltrate composed of histiocytes and multinucleate giant cells. The characteristic appearance is that of a scalloped palisade of histiocytes (top arrow) containing an amorphous-appearing pale to pink deposits in the center (lower arrowhead).
[GOUTY TOPHUS]. The presence of characteristic deposits in periarticular tissue is pathognomonic of chronic tophaceous gout. Gouty deposits may also be seen in certain parenchymal organs such as kidneys. Note the scalloped margin of histiocytes (right arrow) limiting the deposits (left arrowhead). The central portion of the deposits may resemble fibrinoid necrosis of rheumatoid arthritis but close inspection yields the correct diagnosis.
[GOUTY TOPHUS]. Both mononucleate and multinucleate histiocytes are seen. This photomicrograph shows an arc of palisaded mononucleate histiocytes around a collection of crystal deposits.
[GOUTY TOPHUS]. The deposits are made of numerous fine needle-like urate crystals that may give rise to an amorphous appearance at lower magnifications. But close inspection by microscopy shows the true nature of the deposits. This image shows the diagnostic histological appearance of crystal deposits in tissues. Note the fibrillary appearance of this deposit along with small calcified collections. This appearance is unmistaken for gouty tophaceous deposit.