Distribution of E- and N-cadherin in subgroups of non-functioning pituitary neuroendocrine tumours

Purpose Clinically non-functioning pituitary neuroendocrine tumours (NF-PitNETs) present a varying degree of aggressiveness, and reliable prognostic markers are lacking. We aimed to characterise the distribution of E- and N-cadherin in corticotroph, PIT1 and null-cell NF-PitNETs, and link it to the course of the tumours. Methods The distribution of E- and N-cadherin was investigated by immunohistochemistry in a retrospective cohort of 30 tumours of the less common NF-PitNETs (corticotroph ( N = 18), PIT1 ( N = 8) and null-cell PitNETs ( N = 4)). Immunoreactive scores (IRS) were compared to previously presented cohorts of gonadotroph NF-PitNETs ( N = 105) and corticotroph functioning PitNETs ( N = 17). Results We found a low IRS for the extra-cellular domain of E-cadherin (median 0 (IQR 0–0, N = 135)), a medium to high IRS for the intra-cellular domain of E-cadherin (median 6 (IQR 4–9)) and a high IRS for N-cadherin (median 12 (IQR 10.5–12)) throughout the cohort of NF-PitNETs. The corticotroph NF-PitNETs presented a higher IRS for both the extra- and intra-cellular domain of E-cadherin (median 0 (IQR 0–1) and median 9 (IQR 6–12), respectively) than the gonadotroph NF-PitNETs ( p < 0.001 for both comparisons). Presence of nuclear E-cadherin was associated with a weaker staining for the intra-cellular domain of E-cadherin (median 4 (IQR 0.5–6) and median 9 (IQR 9–12), for tumours with and without nuclear E-cadherin, respectively), and with a lower rate of re-intervention ( p = 0.03). Conclusions Considering our results and the benign course of NF-PitNETs, we suggest that a high N-cadherin and downregulation of membranous E-cadherin are not associated with a more aggressive tumour behaviour in these subgroups of NF-PitNETs.