This medical illustration depicts a cross-section of skin layers including the epidermis, dermis, subcutaneous tissue, and muscle, highlighting the presence of a firm, painless, and mobile subcutaneous nodule occurring over bony prominences such as joints. An inset shows the typical size and location of these nodules on the body, including elbows, occiput, wrists, knees, and Achilles tendons. Another inset details the histopathological features of the nodules with labeled components like fibrinoid necrosis, palisading granuloma, and lymphocyte and plasma cell infiltration. Clinical features note that these nodules are associated with severe carditis and follow group A streptococcal infection as part of a delayed hypersensitivity reaction.