MR of recurrent high-grade astrocytomas after intralesional immunotherapy.

PURPOSE To describe the MR findings in six patients with recurrent cerebral astrocytomas before, immediately after, and 3 months after local immunotherapy with tumor-infiltrating lymphocytes and interleukin-2.

METHODS Contrast-enhanced MR studies were obtained in six patients (three with anaplastic astrocytoma and three with glioblastoma multiforme) at the time of tumor recurrence, after a second resection and placement of an Ommaya catheter, at the end of immunotherapy, and thereafter at 3-month intervals. These MR studies were reviewed with special attention to pattern and degree of enhancement, edema, and mass effect.

RESULTS In three patients, gross total removal of recurrent tumor was achieved and postimmunotherapy MR studies showed a flare phenomenon characterized by increased nodular enhancement, increased edema, and mass effect. On the 3-month follow-up examination, these findings had resolved, and no further tumor recurrence was seen during the following 12-month period. Neither of the two patients who had subtotal resection had a flare phenomenon. In one of these patients, the tumor was stable at the 12-month follow-up; the other patient had recurrent tumor at the 6-month follow-up. In the last patient, who also had subtotal tumor resection and progressive enhancement after immunotherapy, tumor progression was rapid.

CONCLUSION After local immunotherapy, increased enhancement, edema, and mass effect are most likely the result of a flare phenomenon, but because rapid tumor progression may produce similar features, follow-up MR studies are indispensable. The flare phenomenon resolved by 3 months in all patients.