Sellar spine: A rare Bony variant of the Sella Turcica

SA Journal of Radiology ISSN: (Online) 2078-6778, (Print) 1027-202X Page 1 of 3 Case Report Sellar spine: A rare Bony variant of the Sella Turcica Authors: Luke D. Metelo-Liquito1 Thandi E. Buthelezi1 Affiliations: 1 Department of Diagnostic Radiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa Corresponding author: Luke Metelo-Liquito, Dates: Received: 12 Dec. 2021 Accepted: 16 Feb. 2022 Published: 28 Apr. 2022 How to cite this article: Metelo-Liquito LD, Buthelezi TE. Sellar spine: A rare Bony variant of the Sella Turcica. S Afr J Rad. 2022;26(1), a2371. https://doi. org/10.4102/sajr.v26i1.2371 Copyright: © 2022. The Authors. Licensee: AOSIS. This work is licensed under the Creative Commons Attribution License. A sellar spine is a rare osseous projection from the dorsum sellae, resulting in variable compression of sellar and suprasellar structures and varied clinical presentations. CT is the diagnostic modality of choice, while variable signal intensity on MRI may mimic a pituitary microadenoma. A patient presented with hypoprolactinaemia and puerperal alactogenesis due to a sellar spine diagnosed on CT Brain. Neurosurgical and endocrine review and pituitary MRI were recommended with subsequent loss to follow-up. Keywords: sellar spine; pituitary fossa; sella turcica; bony variant; hypoprolactinaemia. Introduction A sellar spine is an osseous spur projecting from the dorsum sellae and is a rare variant of the pituitary fossa. This reported case of a sellar spine is unique for two reasons. To our knowledge, this is the first reported sellar spine that arises from the mid-ventral aspect of the dorsum sellae, with most of the previously described cases in the literature arising from the inferior ventral aspect of the dorsum sellae and two arising from the superior aspect of the dorsum sellae.1,2,3,4,5,6,7,8,9,10 Secondly, the history of puerpural alactogenesis and mild hypoprolactinaemia has not yet been described in any of the known reported cases in the literature. Patient presentation A 37-year-old woman with no known co-morbidities presented with a single episode of menorrhagia (1-month history of menstrual bleeding), severe constant headaches for one year, and a history of puerperal alactogenesis in all four of her previous pregnancies. Physical examination was unremarkable. Hormone levels: Thyroid-stimulating hormone (TSH) and prolactin were mildly decreased. Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) were elevated (TSH: 0.33 mIU/L (normal range 0.35–5.50 mIU/L), thyroxine (free T4): 17.5 pmol/L (normal reference range 11.5–22.7 pmol/L), prolactin: 4.7 µg/L (normal range 4.8–23.3 μg/L), FSH: 31 IU/L, LH: 7.7 IU/L, oestradiol: < 19 pmol/L, progesterone: < 0.2 nmol/L). Pelvic ultrasound was unremarkable. She was referred to the radiology department for CT Brain to exclude any pituitary pathology. CT Brain demonstrated a bony spur, consisting of a narrow stalk with a mildly distended tip, arising from the mid-anterior aspect of the dorsum sellae in the midline, projecting anterosuperiorly into the pituitary fossa. The spur measured 5.5 mm in length and compressed the posterior pituitary and the distal posterior aspect of the pituitary stalk (Figures 1 and 2). No other intracranial pathology was noted. Non-urgent neurosurgical review, repeat endocrine profile and MRI of the pituitary gland with dynamic contrast enhancement were recommended; however, the patient was lost to follow-up. Discussion A sellar spine is a rare midline osseous spur, which arises from the dorsum sellae and projects into the pituitary fossa.1 In 1977, Lang et al. described the first case in an article describing atypical ossifications of the sella turcica.11 It is a rare entity with an estimated incidence of 1 in 5000–8000.1,12 Read online: Scan this QR code with your smart phone or mobile device to read online. The leading hypothesis for its development is that it is due to the failure of regression of the most cephalic aspect of the notochord through the clivus into the vertebral column, resulting in a remnant of a notochordal rest in the fetal sella; this remnant then ossifies.1 Other proposed hypotheses by Dietemann et al. include ossification of a dural fold and an ossified vascular channel.1 http://www.sajr.org.za Open Access Page 2 of 3 In all the described cases, the sellar spine was located in the midline in keeping with the foremost theory that it is an ossified remnant of the notochord.1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16 The most consistent imaging morphology of the bony spur among the literature was that of a narrow cylindrical bony stalk with a mildly distended tip and a flattened triangular base in continuity with the dorsum sellae.1,2,3,9,11,12,13 In most cases, the tip had a smooth contour; however, in one of the cases, it was irregular.1,2,3,7,11,12 The maximum described length was 9.0 mm.2 For the remainder of the reported cases, the length of the sellar spine ranged between 3.8 mm and 5.0 mm, making this case the second longest reported case at 5.5 mm.3,4.5,11,12,14 In most of the cases, the sellar spine arose from the inferior aspect of the anterior dorsum sellae with only two cases reported to be arising from the superior aspect.1,2,3,4,5,6,7,8,9,10 To our knowledge, this is the first case, reported, where the sellar spine arises from the mid-anterior aspect giving a ‘figure of 3’ sign of the dorsum sellae in the sagittal plane (Figure 1). The spine most commonly projects in an anterosuperior orientation, with one case observed to be in a more horizontal orientation and one case in an anteroinferior orientation.2 The most commonly compressed structure is the posterior pituitary, in keeping with the anteroinferior origin from the dorsum sellae.8 In the two cases where there was an anterosuperior origin from the dorsum sellae, compression of the pituitary stalk as well as the optic chiasm was observed.5,6 Our case compresses the junction of the stalk and posterior pituitary due to its mid-anterior origin. The age at presentation is varied and ranges from 8 to 53 years, with most of the cases reported between the ages of 13 and 29 years.1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16 A possible explanation for this distribution is the slow progressive growth of the sellar spine over time, as well as normal progressive enlargement of the pituitary gland. This combination increases the probability of compression of the pituitary gland and thus the development of symptoms. This theory is supported by the findings of Hosokawa et al. who demonstrated interval growth of the sellar spine in a patient for whom serial images were obtained over time.14 On the contrary, Chivukula et al. demonstrated no significant growth on serial images obtained from their patient.8 Another possible explanation for the development of Case Report symptoms in our case is the normal growth of the pituitary gland in pregnancy, as po (...truncated)