We describe two cases of 20-year-old girls with pituitary adenoma without genetic history, revealed by visual field defects, with panhypopituitarism in one patient. In both cases, MRI showed giant pituitary adenoma, with invasion of the cavernous and sphenoidal sinuses. Hormone assays revealed normal GH, PRL and IGF1 plasma values. Surgery was incomplete in both cases. Results: Both tumors presented a diffuse pattern. The cells exhibited large nuclei with prominent nucleoli. By immunocytochemistry, focal and low percentages of GH-and PRL-immunoreactive cells were observed respectively in both tumors (GH=1-30 % and PRL=1-5 %). CgA was positive. Cytokeratin and others antibodies against pituitary hormones were negative. Both tumors had high proliferative indexes: Ki-67>3 % (4-10 %) and elevated mitotic number (1-13 mitoses). Detection of p53 was also positive (0.5-5.7 %). The cases were diagnosed as atypical adenomas, according to the WHO classification. Conclusion: The pathological diagnosis of these aggressive GH-PRL tumors has to be taken into account by the clinician to choose the optimal therapeutic strategies. Despite of the important side effects of the radiotherapy, this aggressive treatment might be proposed earlier, even for the young patients, to avoid the tumoral progression.