The objective was to analyze and discuss the implications of a nonmalignant CD30+ late seroma. Methods included collection of seroma fluid and peripheral blood from a patient with a late seroma 22 years after initial breast reconstruction. A panel of 24 monoclonal antibodies was used to detect T-cell receptor Vβ regions present on ˜70% of normal human peripheral blood T lymphocytes. Flow cytometry gated on CD3+ and CD30+ activated T lymphocytes. Cytospins were used to inspect the morphology of the T lymphocytes. Results from the seroma fluid cytology revealed a spectrum of activated T lymphocytes as seen in the blood of patients with immune disorders such as infectious mononucleosis. Cells were judged to be nonmalignant by routine pathology. Flow cytometry revealed >23% of CD3+ T lymphocytes belonged to an expanded T-cell family expressing TCRVβ13.2. Most Vβ13.2 cells expressed T-cell activation antigen CD30 indicating that CD30 is not restricted to anaplastic large cell lymphoma (ALCL) in seroma fluids. A smaller expanded population of CD30+ T lymphocytes expressing TCRVβ 13.2 was detected in the blood. In conclusion, in this index case, an expanded population of CD30+ activated T lymphocytes was detected in seroma fluid surrounding a textured breast implant as well as in peripheral blood, consistent with a local and systemic immune response. The demonstration of an expanded CD30+ T-cell population in a polyclonal background suggests a possible role for bacterial superantigens as a pathogenic factor. These data further suggest that breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) may be the end stage of a CD30+ T-cell lymphoproliferative disorder.