Sphenoid sinus ectopic pituitary adenomas: CT and MRI findings

Abstract

ABSTRACT. Ectopic pituitary adenomas (EPAs) are rare lesions. The purpose of this study was to describe the CT and MRI features of sphenoid sinus EPAs. Eight patients with histology-proven EPAs in the sphenoid sinus, all of whom underwent CT and MRI, were reviewed retrospectively. The following imaging features were analysed: (i) size, (ii) margin, (iii) CT attenuation characteristics and (iv) MRI signal intensity. In addition, the involvement of adjacent structures and the time-intensity curve (TIC) of dynamic contrast-enhanced (DCE) MRI were analysed. All EPAs had well-defined margins and showed no relationship to the intrasellar pituitary gland. The mean size was 28 mm (range, 20-46 mm). On non-enhanced CT, the lesions appeared isodense to grey matter in 7 (88%) patients and hypodense in 1 (12%) patient. Only two patients underwent post-contrast CT, and they showed moderate enhancement. On T 1 weighted images, EPAs appeared isointense in 6 (75%) patients and hypointense in 2 (25%). On T 2 weighted images, the lesions appeared hyperintense in 2 (25%) patients and isointense in 6 (75%). EPAs showed mild to moderate heterogeneous contrast enhancement and exhibited a cribriform-like appearance. Two patients underwent DCE MRI; the TIC showed a rapidly enhancing and slow washout pattern. The following features were also seen: an empty sella, bone changes and involvement of the cavernous sinus (5 patients; 62.5%). In conclusion, a high index of suspicion for EPA and a familiarity with the imaging findings may help to diagnose this rare entity accurately.

Ectopic Sphenoid Sinus Pituitary Adenoma (ESSPA) with Normal Anterior Pituitary Gland: A Clinicopathologic and Immunophenotypic Study of 32 Cases with a Comprehensive Review of the English Literature

“…However, cases were excluded if the lesion arose primarily in the nasopharynx, or involved the pituitary (sella turcica) at the time of presentation or at a later time [7,[42][43][44]. Clinical series were selected if critical information about sinonasal tract or sphenoid sinus lesions was included, but excluded if the information was too generalized [20,40,44]. Duplicate reports were excluded from further evaluation [45].…”

“…Intraoperative assessment of the sella and pituitary can be performed, but pre-operative imaging evaluation will yield the most clinically useful information. Not only will imaging studies document a normal pituitary and sella turcica, but they will also highlight the size of the tumor, give information about the margins and extent of the tumor, and allow for appropriate surgical planning [19,26,40]. It is most important to exclude an invasive pituitary adenoma into the sphenoid sinus, a much more common finding than the ectopic pituitary adenoma.…”

“…MRI shows mild to moderate heterogenous contrast-enhancement, without a unique T1-or T2-weighted image intensity. Non-enhanced CT shows tumors that are iso-to hypo-dense to grey matter, showing modest enhancement in post-contrast studies [26,40].…”

“…The infrequency of these tumors may result in misclassification and subsequent inappropriate management. While there have been two series [20,40] the information focused on imaging findings with only limited information about the histologic findings. Therefore, there is no large comprehensive evaluation of ESSPA when there is a normal sella turcica.…”

Small round blue cell tumors of the sinonasal tract: a differential diagnosis approach

“…Imaging studies are generally encouraged to exclude direct extension (Figure 15), where bone destruction is present. 159,163 Histopathology. The frequently polypoid tumors can be quite sizeable (8 cm), often associated with bone invasion and necrosis ( Figure 15).…”