A 60-year-old woman with atypical
prolactinoma had been treated for 7 years with multiple
therapies, including
dopamine agonists, surgical intervention (5 times), conventional
radiotherapy, and radiosurgery. The patient deteriorated as a result of
tumor enlargement. Ten cycles of TMZ
therapy, 200 mg/m for 5 days every 4 weeks, improved the patient's performance status and caused
tumor shrinkage. Six months after discontinuation of TMZ, the
tumor progressed into
pituitary carcinoma with
tumor regrowth and intraventricular dissemination. TMZ
therapy was ineffective this time. A sixth surgery and salvage
chemotherapy failed to improve the patient's condition, and she died 9 years after the first diagnosis. Throughout the treatment course, O6-methyl-guanine-DNA
methyltransferase (MGMT) was immunonegative in the
tumor specimens, including the TMZ-refractory
pituitary carcinoma. Mutation of p53 was identified in both the atypical
prolactinoma and
pituitary carcinoma. In contrast, major differences were noted for mismatch repair
protein MSH6 immunostaining: Although MSH6 was diffusely immunopositive in the atypical
adenoma, it became immunonegative when the
tumor evolved into TMZ-refractory
pituitary carcinoma.
CONCLUSION: