[Predictive value of the Knosp classification in grading the surgical resection of invasive pituitary macroadenomas. A prospective study of 23 cases]. / Valor predictivo de la clasificación de Knosp en el grado de resección quirúrgica de los macroadenomas invasivos. Estudio prospectivo de una serie de 23 casos.

ABSTRACT

OBJECTIVE: To evaluate our experience regarding the treatment of pituitary macroadenomas with cavernous sinus invasion in a series of 23 cases of transphenoidal resection. MATERIALS, METHODS AND RESULTS: Twenty two patients, fifteen males and seven females, with ages ranging from 27 to 75 (mean of 48), were operated under protocol by a single surgeon between May of 2002 and December of 2004. Preoperatively all lesions were diagnosed by MRI and staged according to the Knosp classification. All tumors had extension to one or both cavernous sinuses. Four patients were considered to be grade 1, two grade 2, one grade 3 and sixteen grade 4. Twenty three operations were performed on twenty-two patients. Twenty cases were the standard transsphenoidal approach, and three were endoscopic. Postoperatively, the excision was classified as Complete or Total, Subtotal or Partial. Mean follow up was 15 months. The variables considered for analysis include invasion and resection grades. All six patients with graded 1 and 2 lesions and two patients with grade 4 lesions underwent a complete resection. Subtotal (greater than 80%) excision was achieved in one patient with a grade 3 tumor and six patients with grade 4 tumors. The remaining seven patients with grade 4 adenomas had a Partial (less than 80%) excision. We compare de resection grade versus invasion grade with exact Fisher test. And there is not estadistical difference (p=0.12). CONCLUSION: The Knosp classification alone cannot predict the behavior of these tumors. In our experience, despite tumor extension to the cavernous sinus, pituitary macroadenomas can be safely resected with low morbidity and mortality.