Patterns of extrasellar extension in growth hormone-secreting and nonfunctional pituitary macroadenomas

Object. Growth patterns of pituitary adenomas have been observed to vary by histopathological subtype. The authors aimed to analyze variations in the patterns of extrasellar extension of nonfunctional macroadenomas (NFMAs) and growth hormone (GH)-secreting macroadenomas. Methods. A retrospective review was conducted of data obtained in 75 patients who underwent transsphenoidal operations for histologically confirmed NFMAs (50 patients) and GH-secreting macroadenomas (25 patients) at the Brigham and Women's Hospital over an 18-month period. Patients with microadenomas and prior operations were excluded from the analysis. Preoperative MR images were reviewed to assess patterns of extrasellar extension in the varying tumor subtypes. Results. The mean maximal tumor diameter in NFMAs and GH-secreting macroadenomas was 26 and 16 mm, respectively (p < 0.0001). Extension of the NFMAs occurred into the following regions: infrasellar, 23 patients (46%); suprasellar, 41 patients (82%); and cavernous sinus, 20 patients (40%). Extension of GH-macroadenomas occurred into the following regions: infrasellar, 18 patients (72%); suprasellar, 4 patients (16%); and cavernous sinus, 4 patients (16%). Compared with GH-adenomas, NFMAs were more likely to develop suprasellar extension (82% vs 16%, p < 0.0001), cavernous sinus extension (40% vs 16%, p = 0.04), and isolated suprasellar extension (30% vs 4%, p = 0.0145). GH-macroadenomas had higher overall rates of infrasellar extension (72% vs 46%, p < 0.05), and isolated infrasellar extension (52% vs 6%, p < 0.0001). Of the 13 GH-macroadenomas with isolated infrasellar extension, 5 (42%) met WHO criteria for atypical adenomas. Conclusions. Substantial differences in extrasellar growth patterns were observed among varying histological subtypes of pituitary macroadenomas. Despite smaller tumor diameters, GH-macroadenomas demonstrated a proclivity for infrasellar extension, whereas NFMAs exhibited preferential extension into the suprasellar region. (DOI: 10.3171/2010.7.FOCUS10155)