Atypical pituitary abscess lacking rim enhancement and diffusion restriction with an unusual organism, Moraxella catarrhalis: A case report and review of the literature

Abstract

Background: Pituitary abscess (PA) can be fatal if diagnosed late. Rim enhancement is a typical radiological finding of PA on postgadolinium T1-weighted magnetic resonance imaging (MRI). Diffusion-weighted imaging is helpful in distinguishing PA from other sellar cystic lesions. Herein, we report the first atypical case of PA showing neither rim enhancement nor diffusion restriction with an unusual organism, Moraxella catarrhalis. Case Description: A 77-year-old woman presented with headache, polyuria, polydipsia, and fatigue for a month before presenting to a local hospital. MRI showed pituitary enlargement with contrast enhancement. She had neither fever nor visual deficits and was followed up with hormonal replacement. Six months later, she complained of visual impairment, and MRI showed further pituitary enlargement with a thickened stalk compressing the optic chiasma. Neither rim enhancement nor diffusion restriction was observed. Endoscopic endonasal transsphenoidal surgery was performed based on the radiological diagnosis of lymphocytic hypophysitis or pituitary tumors. A thick, creamy yellow pus was drained from the sellar lesion. Intraoperative rapid histopathological findings revealed polymorphonuclear leukocytes infiltrating the pituitary gland. PA was diagnosed, and irrigation and open drainage of the abscess was performed. Bacterial culture of the pus detected M. catarrhalis by mass spectrometer, confirming the diagnosis. She underwent appropriate antibiotic administration, and her visual deficits improved. Conclusion: We report the first atypical case of PA showing neither rim enhancement nor diffusion restriction with M. catarrhalis. Even if preoperative findings are not suggestive of PA, it should be considered as a differential diagnosis. Intraoperative rapid histopathological findings are useful for accurately diagnosing PA and initiating appropriate surgical treatment.

Pituitary Abscess: A Challenging Preoperative Diagnosis—A Multicenter Study

“…PAs represented 0.7% of all pituitary gland pathologies. This finding is consistent with previous data from the literature which estimates an incidence of 0.2 to 1.1% of pituitary/sellar lesions [ 3 , 6 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Similar to what is previously described, we also found a gender predilection, with women being more affected than men [ 6 ].…”

“…Our results allow us to draw the following conclusions. First, that the presence of DI should raise the suspicion of PA, in the absence of clinical and radiological evidence of other pituitary pathology [ 7 , 22 , 23 ]. Second, that previous clinical history of chronic infection, recent dental treatments, steroidal treatments, immune-depression, or other co-morbidities exposing to the risk of infections [ 24 ], should always put PA among the differential diagnoses considered, even in the absence of fever or hyper-leukocytosis.…”

“…Second, that previous clinical history of chronic infection, recent dental treatments, steroidal treatments, immune-depression, or other co-morbidities exposing to the risk of infections [ 24 ], should always put PA among the differential diagnoses considered, even in the absence of fever or hyper-leukocytosis. Third, the absence of restriction on DWI MRI sequences cannot completely rule out the suspicion of PA commonly used for the diagnosis of cerebral abscess: in fact, it seems that the paramagnetic susceptibility effect at the base of the skull could affect signal scattering and cause artifacts due to the vicinity of the cranio-facial pneumatized sinuses [ 22 , 24 ]. The intrinsic limitations of the MRI have pushed us to try other imaging methods and specifically those provided by nuclear medicine.…”

A Pituitary Abscess Caused by Morganella morganii: A Case Report

“…Several pathogens have been isolated from patients with confirmed PA [ 5 , 6 , 8 , 9 ]. In our case, the gram-negative bacillus M. morganii was isolated from the drained PA. A few case reports showed brain abscess caused by M. morganii [ 11 , 13 ].…”

“…Several PA case reports cited the isolation of pathogens such as Staphylococcus spp. and Streptococcus spp., Moraxella catarrhalis, Mycobacterium tuberculosis, and fungi such as Aspergillus fumigatus [ 5 , 6 , 8 , 9 ].…”