A literature report was received on 27Sep05 concerning a 65 year old Caucasian female. No details were provided regarding the vaccinee's medical history or concomitant medications. Within a few days of vaccination with an influenza vaccine (brand unspecified) in her right arm, the vaccinee developed pruritic nodule at the injection site, which grew to 2cm in diameter. Despite being prescribed with antibiotics and a warm compress, the lesion continued to increase in size. A biopsy, performed six weeks after the initial presentation, revealed a granulomatous and mixed cellular infiltration that was interpreted as reactive in nature. No pathological micro organisms were identified histologically or in cultures obtained from lesional tissue. Within a month after the initial biopsy, the nodule had enlarged to 5cm and had begun to ulcerate. The lesion was resected and revealed a similar reactive histology compared to the initial biopsy. Over the next two years, the lesion continued to increased in size and ulcerate, despite numerous attempts at resection and various courses of oral and topical corticosteroid therapy. Cultures for infectious microorganisms were consistently negative. A course of low dose radiotherapy was administered three years after initial presentation and resulted in complete regression of the lesion and healing of the overlying epidermis. The vaccinee has not had a recurrence within a nine year follow up period, after radiation treatment. Analysis of the tissue samples showed that they all had similar histopathological finding. The epidermis was ulcerated and the full thickness of the reticular dermis was effaced by a sheet of cells extending into subcutaneous fate. The inflammatory proliferation was comprised of a cellular, atypical but polymorphic lymphohistiocytic population of mononuclear cells. The proliferation was characterized by mostly small to medium seized lymphocytes, some with a Plasmacytoid appearance, on a histolytic background. Larger immunoblastic cells made up a small component of the infiltration. In addition, there were scattered areas of necrotizing granulomatous inflammation within the cellular dermal infiltration. The majority of the small lymphoid cells were positive for CD3 and CD5 pan T cell markers. Some small lymphocytes stained with the pan B-cell marker CD20. The larger lymphoid cells predominately marked with CD20. Lymphoid follicle formation was evident in the initial resection but was not present in subsequent material. Special stains for acid fast bacterial and fungal organisms were consistently negative. In situ hybridization studies for kappa and lambda immunoglobulin light chains revealed polytypic plasma cell populations with kappa or lambda ratios of approximately three to one. PCR studies revealed neither clonal immunoglobulin heavy chain nor T-cell receptor gene rearrangement. The authors suggest that although the large majority of pt's received vaccinations do not developed atypical lymphoid proliferations in the vaccination site, the antigenic stimulus of the influenza virus components and/or vaccination associated adjuvants and carriers more than likely triggered an aberrant inflammatory response in this pt. No further information is expected.