Ectopic Pituitary Adenomas

Fig. 20.1

Ectopic pituitary adenoma. (a) Sagittal T1-weighted post-gadolinium image. (b) Coronal T1-weighted post-gadolinium image. An enhancing lesion is located in the roof of the right sphenoid sinus (white arrow), anterior to the sella. The pituitary gland within the sella is normal in size. (c) Intraoperative photo taken via endoscopic endonasal approach (white arrow) showing the ectopic pituitary adenoma arising from the roof of the right sphenoid sinus

20.2.2 Histopathology

Histopathological findings are similar to those seen in classic PAs. Immunostaining may show reactivity for any of the anterior pituitary hormone cell types.
The MIB-1 labeling index in EPAs is usually less than 1 % [14].
Malignant transformation of an EPA is rare, but it has been reported [15].
Normal histology of the anterior pituitary gland can be seen along with the finding of an EPA [16].

20.3 Clinical Management

EPAs are often mistaken for other tumors prior to pathological analysis, and a thorough endocrine work-up is not always performed. This work-up should be done as soon as possible (before or after surgery), to characterize the hormonal tumor profile.
Resection depends on the location and the relationship of the tumor to surrounding neurovascular structures.
Endoscopic endonasal techniques have been utilized to treat these tumors (Fig. 20.1c) [17].
Suprasellar EPAs may be treated via craniotomy (typically pterional or subfrontal) or extended endonasal approaches.
As with classic PAs, postoperative management is focused on normalization of hormonal hypersecretion syndromes and achieving tumor control with any combination of medications and adjunctive radiation-based therapy.
Stereotactic radiosurgery may be used as needed to treat residual areas of EPAs.
Sphenoid sinus EPAs recur in approximately 14 % of patients following tumor resection [14].

References

Das CJ, Seith A, Gamanagatti S, Goswami R. On the AJR viewbox. Ectopic pituitary adenoma with an empty sella. AJR Am J Roentgenol. 2006;186:1468–9.CrossRefPubMed

Appel JG, Bergsneider M, Vinters H, Salamon N, Wang MB, Heaney AP. Acromegaly due to an ectopic pituitary adenoma in the clivus: case report and review of literature. Pituitary. 2012;15:S53–6.CrossRefPubMed

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