Differential Diagnoses of Sellar/Suprasellar Masses Causing Bitemporal Hemianopsia
MRI of the brain with and without contrast using thin-section pituitary protocol (≤0.5 cm slice thickness) is the gold standard imaging modality for evaluating sellar/suprasellar masses presenting with bitemporal hemianopsia. 1, 2
Primary Differential Diagnoses
Most Common Lesions
Pituitary macroadenomas are the most common suprasellar lesions in adults causing bitemporal hemianopsia due to optic chiasm compression. 3
- Nonfunctioning pituitary adenomas present with mass effect symptoms including visual field defects without hormonal hypersecretion 3
- Prolactinomas can present as giant suprasellar masses with visual symptoms, though they may lack typical hyperprolactinemia symptoms, particularly in adolescent males 4
- Other functioning adenomas (growth hormone, ACTH, TSH-secreting) can cause bitemporal hemianopsia when they reach macroadenoma size (>1 cm) 1
Important Alternative Diagnoses
Craniopharyngiomas are critical to distinguish from pituitary adenomas, as they demonstrate characteristic calcification on CT imaging that may not be readily apparent on MRI alone. 1
- These tumors commonly affect the sellar/suprasellar region and can mimic pituitary macroadenomas on initial imaging 4
- CT of the head is complementary to MRI for detecting calcification patterns 1
Meningiomas of the sellar/suprasellar region can compress the optic chiasm and present with bitemporal hemianopsia. 1
Rathke's cleft cysts are benign epithelial cysts that can enlarge and cause chiasmal compression. 2
Pituicytomas are rare WHO Grade I tumors originating from neurohypophyseal glial cells that demonstrate high vascularity and intense enhancement, potentially mimicking pituitary macroadenomas. 5
- These tumors show significant tumor vascularity and can cause massive intraoperative hemorrhage 5
- Should be suspected when imaging shows high enhancement with prominent vascular components 5
Prolactin-secreting gangliocytomas are exceedingly rare neuronal tumors that can present with markedly elevated prolactin levels and visual field defects, but characteristically fail to shrink with dopamine agonist therapy despite normalization of prolactin levels. 6
Less Common but Important Considerations
Optic nerve gliomas involving the pre-chiasmatic or chiasmatic segments can cause visual field defects. 1
Germinomas and other germ cell tumors can arise in the suprasellar region, particularly in children and adolescents. 1
Arachnoid cysts in the suprasellar cistern can cause mass effect on the optic chiasm. 1
Metastatic lesions to the sellar/suprasellar region should be considered in patients with known malignancy. 1
Diagnostic Workup Algorithm
Immediate Initial Steps
Obtain comprehensive ophthalmologic evaluation including visual acuity (logarithm of the minimum angle of resolution measurement), visual field testing (ideally Goldmann perimetry), fundoscopy, and consider optical coherence tomography for baseline assessment. 1, 2
Perform complete hormonal screening including thyroid function tests (TSH, free T4), morning cortisol and ACTH, prolactin, sex hormones (LH, FSH, testosterone/estradiol), and growth hormone/IGF-1. 2, 7
Imaging Protocol
High-resolution MRI of the brain with and without IV contrast is the preferred initial imaging modality, providing detailed visualization of the pituitary gland, infundibulum, optic chiasm, and assessment for cavernous sinus invasion. 1, 2, 7
CT of the head without contrast should be obtained as complementary imaging to detect calcification (suggesting craniopharyngioma), assess bone involvement, or evaluate for acute hemorrhage if pituitary apoplexy is suspected. 1
Advanced Diagnostic Testing
Bilateral inferior petrosal sinus sampling (BIPSS) should be performed when pituitary lesions <6 mm are detected, MRI is negative/equivocal, or there is discordance between biochemical testing and imaging. 2
Management Approach
Surgical Indications
Transsphenoidal resection is the mainstay of treatment for most sellar tumors except prolactinomas, with complete resection being the treatment of choice when feasible. 2, 7
- Modern image-guided surgery techniques improve precision and reduce surgical complications 7
- Avoid attempting complete resection of tumors enveloping major vessels or involving vital neural structures, as risks outweigh benefits 2, 7
Medical Management Exception
Prolactinomas should be treated with dopamine agonist therapy (cabergoline) as first-line management, reserving surgery for cases with extensive mass effect, failed medical therapy, or atypical features suggesting alternative diagnosis. 4, 6
- Failure of tumor shrinkage despite prolactin normalization with dopamine agonists should raise suspicion for alternative diagnoses such as gangliocytoma 6
Timing Considerations
Do not delay surgical planning for resectable non-prolactinoma lesions causing visual symptoms, as visual recovery becomes unlikely after one month postoperatively, with children <6 years having particularly poor visual outcomes. 1, 2, 7
Critical Pitfalls to Avoid
Bilateral ocular staphylomas (scleral ectasia) can rarely mimic bitemporal hemianopsia and should be considered when imaging rules out sellar/suprasellar masses. 8
Highly vascular lesions such as pituicytomas require recognition prior to transsphenoidal approach to prevent uncontrolled intraoperative hemorrhage; conventional cerebral angiography may be warranted when imaging suggests unusual vascularity. 5
Spontaneous tumor regression can rarely occur with pituitary macroadenomas, necessitating repeat imaging for surgical planning if significant time has elapsed since diagnosis. 3
Lifelong endocrine surveillance is mandatory following treatment, as hormonal deficiencies may develop or progress over time even after successful resection. 2, 7
Postoperative Management
Obtain histopathological assessment including immunostaining for pituitary hormones and Ki-67, with additional immuno-profiling when relevant to accurately classify the neoplasm. 1, 7
- Ki-67 ≥3% combined with local invasion on imaging predicts 25% recurrence rate in pediatric cases 1, 7
Delayed surveillance imaging >3 months following transsphenoidal surgery is recommended for known subtotal resection or nonfunctioning adenomas, guided by tumor pathology and patient symptoms. 1, 2