A Rare Case of Kimura Disease in the Wrist

Kimura disease is a rare benign chronic inflammatory disorder of unknown etiology that typically involves lymph nodes and soft tissues. This disease is most common in middle-aged Asian men. Although the disorder most frequently involves the head and neck region, it has also been reported to involve the extremities. Lesions typically show follicular lymphocytic hyperplasia with prominent interfollicular venules and a mixed inflammatory infiltrate, including numerous eosinophils. We describe a case of Kimura disease in a 29-year-old female presenting with a slowly enlarging, painless soft tissue mass in her left wrist for five months. The lesion was non-tender, mobile, and compressible. Lab results were significant for peripheral blood eosinophilia and elevated IgE. Microscopically, the mass was circumscribed, with apparent fibrous capsule or pseudocapsule, prominent high-endothelial venules, and inflammatory cells consisting of lymphocytes and eosinophils. There were prominent secondary B-lymphocytic follicles with germinal centers containing many penetrating small blood vessels, and some follicles exhibiting follicle lysis and a small amount of eosinophilic extracellular material. Polykaryocytes were noted in many germinal centers. Angiolymphoid hyperplasia with eosinophilia, a main differential diagnosis of Kimura disease, was considered; however, the combined clinical and morphologic findings appeared to be more consistent with Kimura disease, particularly in the context of eosinophilia and elevated IgE level. Kimura disease may present as a rare cause of a soft tissue mass and a diagnostic challenge for clinicians and pathologists, especially in less common sites such as the wrist.