Stalking the stalk: Isolated pituitary stalk thickening and predictive factors for proliferative disease

Abstract

Background: Few studies have evaluated predictive factors of isolated pituitary stalk thickening (iPST) in children.

Methods: In this retrospective study, radiology, endocrinology, and neuro-oncology databases were interrogated to identify patients with iPST between January 2000 and June 2019. A blinded, longitudinal assessment of MRIs was performed using quantitative, semi-quantitative, and qualitative metrics. Neuroimaging parameters were correlated to clinical parameters.

Results: Forty-seven patients were identified, with 40 meeting the inclusion criteria. Median age at baseline MRI was 9.6 years (range 0.9-17.5) with median follow-up of 5.2 years (range 0.3-18.6). Twenty-five (63%) were female. Thirty-four (85%) had pituitary dysfunction, including 31 with central diabetes insipidus (cDI). cDI was not predictive of proliferative disease (PfD): 69% of those with presumed primary hypophysitis (PPH) versus 93% with PfD (P = .1). Fourteen (35%) patients were diagnosed with PfD (germinoma = 8, Langerhans cell histiocytosis = 5, lymphoma = 1) at median of 1.3 years (range 0.3-4.0) after initial MRI. Progressive thickening of the stalk over time was associated with PfD (86% vs 4% in PPH, P < .0001), as was thickening of the entire stalk (56% in PfD vs 27% in PPH, P < .0001) with different imaging trends over time observed in PfD versus PPH. A "sack of marbles" appearance with heterogeneous enhancement on post-contrast imaging was associated with germinoma.

Conclusions: In this cohort, 35% of children with iPST were diagnosed with PfD. The association of cDI and PfD was not statistically significant. Progressive thickening of the entire stalk was predictive of PfD and a "sack of marbles" pattern was found to be highly suggestive of germinoma.

Keywords: CSF pleocytosis; LCH; germinoma; hypophysitis; pituitary stalk thickening.

Figure 1.

CONSORT diagram showing the cohort examined in this retrospective study. iPST, isolated pituitary stalk thickening.

Figure 2.

MRI demonstrating isolated pituitary stalk thickening (iPST) on sagittal post-contrast images. (A) and (B) are patients with primary hypophysitis (PPH) (13-year-old [y/o] M and 5 y/o M, respectively) showing diffuse enhancement with only partial stalk thickening. (C) is a patient with LCH (15 y/o M) with total stalk thickening and homogeneous enhancement. (D) is a patient (8 y/o M) with Langerhans cell histiocytosis (LCH) with upper/middle stalk thickening with homogeneous enhancement. (E) and (F) is a patient (7 y/o F) with an initial diagnosis of iPST (E) and final diagnosis of germinoma (F, 3 months later), and (G) and (H) is a patient (10 y/o M) with an initial diagnosis of iPST (G) and final diagnosis of germinoma (H, 2 years later) both showing a “sack of marbles” appearance and total stalk thickening.

Figure 3.

Imaging and cerebrospinal fluid (CSF) findings. Spider plot showing the (A) anterior–posterior (AP) and (B) transverse diameters of the pituitary stalk over time. Linear mixed modeling to predict the trajectory of growth of (C) AP and (D) transverse diameters over time stratified by proliferative disease status. Dot plots showing the distribution of (E) white blood cell (WBC), (F) protein, and (G) glucose levels in CSF. Normal range represented between dotted lines.