Erythema elevatum diutinum.

Erythema elevatum diutinum (EED) is a rare and chronic form of cutaneous vasculitis often associated with systemic diseases including such hematologic malignancies as immunoglobulin A monoclonal gammopathy, multiple myeloma, and non-Hodgkin lymphoma, as well as such autoimmune disorders and infections HIV and streptococcus. Clinically, EED presents as symmetrical red-to-brown papules, plaques, or nodules, primarily on extensor surfaces including the elbows, knees, and hands. These lesions may be asymptomatic or associated with burning, tenderness, or pruritus, and their chronic nature often leads to fibrosis and discoloration over time. Histologically, EED exhibits leukocytoclastic vasculitis associated with neutrophilic infiltration in the upper and mid-dermis with sparing of the papillary and periadnexal dermis, fibrin deposition, and progressive dermal changes, including granulation tissue and fibrosis in late-stage lesions. Although no cure exists, the first-line treatment is dapsone. Corticosteroids and immunosuppressive agents are employed for resistant cases. Early diagnosis and management are essential, particularly given the condition's potential to signal serious underlying systemic diseases. Although EED lesions may persist for decades, treating the underlying conditions can influence the disease course, offering a pathway to improved outcomes.