Fibroadipose tissue heavily infiltrated by a marked inflammatory infiltrate, composed of dense, diffuse chronic inflammatory cells—predominantly mature lymphocytes and plasma cells—interspersed with histiocytes and reactive fibroblasts. The background matrix is loose, edematous, and focally myxoid, with proliferating small capillaries lined by reactive endothelial cells. Scattered neutrophils and areas of nuclear debris are present. No cellular atypia, abnormal mitotic figures, or malignancy is identified.
Swelling in the right anterior compartment of the thigh, noted on examination to have a fluctuant mass containing clear fluid.
Two soft tissue fragments collectively measured 1x0.8x0.2 cm, totally embedded.
Right anterior thigh tissue biopsy: