Objectives Sphenoid sinus mucosal thickening (SSMT) is described in small preliminary studies in the setting of pituitary apoplexy (PA). The aim of this study was to explore the possible association between PA and SSMT, and the microbial profile of SSMT.

Design Single-centre case notes and tissue samples review (2007–2016).

Subjects PA group: radiological/histologically confirmed PA; control group: non-functioning pituitary adenomas (NFPAs).

Methods SSMT was measured on presenting MRI scans (pathological >1 mm). Forward stepwise logistic regression was used to identify factors associated with SSMT. Sphenoid sinus mucosal specimens were microbiologically profiled by PCR in a subset.

Results Imaging arm: 50 NFPA and 47 PA patients included. In multivariate analysis of both the PA and NFPA groups, the presence of PA was the only factor associated with SSMT (OR=0.043, 95% CI 0.012 to 0.16; p<0.001). In multivariate analysis of the PA group alone, a shorter time from symptom onset to presenting MRI scan (OR=0.12, 95% CI 0.026 to 0.54; p=0.006) and more severe grade of apoplexy (OR=7.29, 95% CI 1.10–48.40; p=0.04), were associated with SSMT. Microbiological arm: 5 PA and 5 NFPA patients included. PA patients harboured microbiota similar to that seen in sinusitis, unlike NFPA patients.

Conclusions SSMT is associated with PA, especially during the acute phase. SSMT is also associated with microbiota seen in sinusitis. Our results require further validation.