<prompt> 50-year-old, presents with enlarged knuckles and large subcutaneous nodules near her elbows. Her proximal interphalangeal PIP joints are hyperextended and her distal interphalangeal DIP joints are flexed. If the nodules were biopsied, which of the following would best describe their likely histological appearance?Amorphous crystalline mass surrounded by macrophagesCystic space caused by myxoid degeneration of connective tissueDarkly pigmented synovium with an exuberant, villous growthFibrinoid necrosis surrounded by palisading epithelioid cells  <response>: Swan-neck deformity PIP joints hyperextended and DIP joints flexed, enlarged knuckles, and subcutaneous nodules are classic clues for rheumatoid ahritis. The subcutaneous rheumatoid nodules are composed histologically of areas of fibrinoid necrosis surrounded by palisading epithelioid cells.Gout tophi are amorphous crystalline masses surrounded by macrophages.Ganglion cysts are small cystic spaces caused by myxoid degeneration of connective tissue.Pigmented villonodular synovitis causes darkly pigmented synovium with exuberant villous growth. 