Knosp and revised Knosp classifications predict non-functioning pituitary adenoma outcomes: a single tertiary center experience

Non-functioning pituitary adenomas (NFPAs) are hormonally inactive benign tumors, usually diagnosed as macro-adenoma. The aim of our research was to analyze the clinical and hormonal characteristics of NFPAs using Knosp and revised Knosp classifications. Furthermore, we aimed to assess the possibility of predicting surgical remission after surgery. This was a prospective descriptive-analytical study. We selected 30 patients with non-functioning pituitary adenomas by excluding all the clinical and biochemical evidence of hormone excess. Cavernous sinus invasion was evaluated by Knosp and revised Knosp classifications. The mean age was 50.8 ± 11.6 years, and 63.3% of the patients were women with a sex ratio F/M of 1.7. Patients with a Knosp grade greater than two experienced more symptoms, such as headaches (<i>P</i> = 0.014) and declining visual acuity (<i>P</i> = 0.095). Additionally, these patients were found to have a higher prevalence of growth hormone deficiency compared to those with a Knosp grade of two or lower (<i>P</i> = 0.037). The revised Knosp classification showed no significant difference between patients with invasive adenomas (grade ≥ 3B) and patients with non-invasive adenomas (grade ≤ 3A) regarding clinical and hormonal status. However, we noticed that patients with non-invasive adenomas (grade ≤ 3A) had significant surgical remission (<i>P</i> = 0.008). A preoperative description of cavernous sinus invasion in NFPAs provided by the Knosp and revised Knosp classifications is mandatory. Our report shows that the revised Knosp classification is superior in predicting surgical remission than the Knosp classification, with no significant difference in evaluating the clinical and hormonal status between the two classifications.