The sellar and parasellar region houses complex anatomical structures including the pituitary gland, optic chiasm, hypothalamus, infundibulum, cavernous sinuses, and adjacent bony and dural elements. Masses in this area are diverse in etiology—ranging from benign tumors to vascular anomalies and cysts—and often present with endocrine dysfunction, visual disturbances, or incidental radiologic findings.

Anatomy

Anatomical Landmarks:

• Sellar region: Sella turcica of sphenoid bone, housing the pituitary gland.
• Suprasellar region: Area superior to the diaphragma sellae, near the optic chiasm, hypothalamus, third ventricle.
• Sellar region: Primarily comprises the sella turcica and pituitary gland.
• Parasellar region: Includes the cavernous sinuses, suprasellar cistern, optic chiasm, hypothalamus, and infundibulum.

Anatomic composition of the sellar and parasellar regions:

![The pituitary gland resides within the sella turcica, suspended in place by the infundibulum. It consists of the anterior pituitary or adenohypophysis derived from Rathke’s pouch, and the posterior pituitary or neurohypophysis, which originates from neural ectoderm. The adenohypophysis consists of five subtypes of secretory cells that release growth hormone, follicle-stimulating/luteinizing hormones, adrenocortical-stimulating hormone, thyroid-stimulating hormone, and prolactin hormone, respectively. These cells are stimulated by the hypothalamus, which drives pituitary signaling of target organs. The neurohypophysis includes the infundibulum and the pars nervosa, a collection of hypothalamic axon terminals that store oxytocin and vasopressin, hormones which are released directly into the hypophyseal portal system. The median eminence, a bulge along the inferior hypothalamus, is an area devoid of blood–brain barrier allowing for entry of hypothalamic hormones into the circulation. A potential space known as Rathke’s cleft lies between the adenohypophysis and neurohypophysis, along with a collection of cells along the border of these two structures known as the pars intermedia, involved in the production of melatonin.

Abad, A.P. Sellar and Parasellar Pain Syndromes. Curr Pain Headache Rep 23, 7 (2019). https://doi.org/10.1007/s11916-019-0740-x](attachment:f2c6fb9b-42fa-4f81-a193-f837f1c8e32e:11916_2019_740_Fig1_HTML.webp)

The pituitary gland resides within the sella turcica, suspended in place by the infundibulum. It consists of the anterior pituitary or adenohypophysis derived from Rathke’s pouch, and the posterior pituitary or neurohypophysis, which originates from neural ectoderm. The adenohypophysis consists of five subtypes of secretory cells that release growth hormone, follicle-stimulating/luteinizing hormones, adrenocortical-stimulating hormone, thyroid-stimulating hormone, and prolactin hormone, respectively. These cells are stimulated by the hypothalamus, which drives pituitary signaling of target organs. The neurohypophysis includes the infundibulum and the pars nervosa, a collection of hypothalamic axon terminals that store oxytocin and vasopressin, hormones which are released directly into the hypophyseal portal system. The median eminence, a bulge along the inferior hypothalamus, is an area devoid of blood–brain barrier allowing for entry of hypothalamic hormones into the circulation. A potential space known as Rathke’s cleft lies between the adenohypophysis and neurohypophysis, along with a collection of cells along the border of these two structures known as the pars intermedia, involved in the production of melatonin.

Abad, A.P. Sellar and Parasellar Pain Syndromes. Curr Pain Headache Rep 23, 7 (2019). https://doi.org/10.1007/s11916-019-0740-x

![Anatomy revised. T1W midline sagittal (A) and T1W coronal (B and C) MRIs through the pituitary fossa.

Renowden S. The parasellar region and central skull base. Practical Neurology. 2014;15(1):26-41. doi:https://doi.org/10.1136/practneurol-2014-001030](attachment:bf493f67-1df1-41c2-b5a7-ad7aaae19dbf:practneurol-2015-February-15-1-26-F1.large.jpg)

Anatomy revised. T1W midline sagittal (A) and T1W coronal (B and C) MRIs through the pituitary fossa.

Renowden S. The parasellar region and central skull base. Practical Neurology. 2014;15(1):26-41. doi:https://doi.org/10.1136/practneurol-2014-001030

Embryology

![Normal development of the pituitary gland

Shields, R., Mangla, R., Almast, J. et al. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging 6, 241–260 (2015). https://doi.org/10.1007/s13244-015-0401-5](attachment:46bce3df-5c63-4183-97f0-6a02a5c5c4fb:13244_2015_401_Fig2_HTML.webp)

Normal development of the pituitary gland

Shields, R., Mangla, R., Almast, J. et al. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging 6, 241–260 (2015). https://doi.org/10.1007/s13244-015-0401-5

Etiopathogenesis & Differential Diagnosis

MOuSTACHE:

• Meningioma/Metastasis
• Optic pathway glioma
• Sellar lesion with extension (macroadenoma)