A 30-year-old woman presented with headache and blurry vision. The neurological examination findings were unremarkable. MRI of the sella revealed a midline, well-defined osseous structure located posterior to the pituitary gland. On axial, inverted axial and coronal T2-weighted images, the lesion appeared isointense to the bone, tapering anteriorly from the dorsum sellae toward the posterior pituitary gland (Figure 1A–C). On unenhanced coronal and sagittal T1-weighted and inverted sagittal T1-weighted images, the lesion exhibited a signal intensity identical to that of the bone within the posterior pituitary region, maintaining direct continuity with the dorsum sellae (Figure 1D–F). No enhancement was observed on post-contrast T1-weighted sequences (Figure 2A,B). The osseous nature of the lesion and its continuity with the dorsum sellae were clearly delineated on the sagittal post-contrast T1-weighted images (Figure 2A). Based on these MRI findings, a diagnosis of sellar spine was suggested. A computed tomography of the sella turcica confirmed the presence of an osseous lesion, originating from the midline of the anterior surface of the hypertrophic dorsum sellae (Figure 3). Given the presence of a sellar lesion, the patient was referred to an endocrinologist for further evaluation and management. Clinical examination and review of the systems revealed no evidence of endocrine dysfunction. Laboratory assessments revealed normal pituitary hormone levels. The patient’s visual complaint was attributed to elevated intraocular pressure, which was identified during ophthalmological evaluation and resolved with medical therapy.

Figure 1.

Unenhanced MRI of the pituitary gland. (A) Axial, (B) inverted axial, (C) coronal T2-weighted and (D) coronal, (E) sagittal, (F) inverted sagittal T1-weighted images demonstrate the sellar spine as a lesion with signal intensity identical to bone, tapering anteriorly from the dorsum sellae toward the posterior pituitary gland (arrows).

Figure 2.

Gadolinium-enhanced MRI of the pituitary gland. (A) Sagittal and (B) coronal T1-weighted images demonstrate no enhancement in the sellar spine (arrows) and clearly delineate the osseous nature of the lesion and its continuity with the hypertrophic dorsum sellae (star).

Figure 3.

Bone-window coronal reformatted (A), axial 3D volume rendered (B) and sagittal reformatted (C) CT images of the sella turcica demonstrate the sellar spine as a bone spur (arrowheads), arising from the midline of the anterior surface of the hypertrophic dorsum sellae (arrow).

The sellar spine is a rare osseous anomaly that arises from the midline of the lower anterior dorsum sella and protrudes into the pituitary fossa, representing the ossification of the cephalic remnant of the notochord. ^{Reference Ambrosetto, Frank, Brayda and Busacca1} Its reported incidence ranges from one in 5000 to one in 8000. ^{Reference Ambrosetto, Frank, Brayda and Busacca1,Reference Dietemann, Lang, Francke, Bonneville, Clarisse and Wackenheim2} Although most cases are discovered incidentally without clinical significance, the sellar spine has occasionally been associated with hypopituitarism, galactorrhea, visual disturbances, or headache. ^{Reference Abs, Van Breusegem, Verhaert, Smet and Parizel3–Reference Orr, Braunreiter, Keefe, Christy and Betz6} Postnatal growth of the sellar spine has also been reported and may account for its occurrence in adolescents and adults. ^{Reference Hosokawa, Yamada, Sato, Tanami, Kurihara and Oguma7} Classically, the sellar spine appears as a bony spur arising from the dorsum sella, extending anteriorly and slightly upward toward the pituitary fossa. On imaging, it usually presents as a compact bone structure that is hypointense on both T1- and T2-weighted MRI sequences; however, depending on its marrow content, it may show hyperintense signals. ^{Reference Ambrosetto, Frank, Brayda and Busacca1–Reference Orr, Braunreiter, Keefe, Christy and Betz6,Reference Radmanesh and Young8} The lesion was midline, osseous in signal intensity and directly continuous with the hypertrophic dorsum sella, which are key diagnostic features distinguishing the sellar spine from pituitary or parasellar masses. The absence of contrast enhancement and the identical signal to the dorsum sella confirmed its benign, bony nature. Inverted T1- and T2-weighted images were particularly helpful in delineating the osseous configuration and its continuity with the dorsum sella. Because pituitary evaluations are most often performed using MRI, awareness of these characteristic imaging features is crucial. Recognition of a midline, nonenhancing osseous lesion with a signal identical to the hypertrophic dorsum sella on both conventional and inverted MRI sequences with additional CT images allows accurate diagnosis of sellar spine and prevents further clinical and laboratory investigations or surgical intervention.