Sellar surprises: a single-centre experience of unusual sellar masses

Abstract

Background: Most common incidentally detected sellar-suprasellar region (SSR) masses are pituitary adenomas, followed by craniopharyngioma, rathke's cleft cyst, hypophysitis, and meningioma. Besides these, certain unusual SSR lesions can sometimes present as diagnostic challenges, where diagnosis is often made post-operatively on histopathology, the pre-operative suspicion of which might have influenced the management strategies. Series describing such masses are few.

Objective: To present clinical, biochemical, and radiological characteristics and management outcomes of rare SSR lesions other than pituitary adenomas, craniopharyngioma, rathke's cleft cyst, hypophysitis, and meningioma.

Design, setting, patients: Retrospective case record analysis of patients with uncommon SSR masses (from January 2006 to December 2016).

Results: Our series consisted of ten patients, five with neoplastic and five with non-neoplastic lesions. Neoplastic masses included granular cell tumor (n = 2), astrocytoma (n = 1), malignant peripheral nerve sheath tumor (MPNST, n = 1), and metastasis from occult papillary carcinoma of thyroid (n = 1), while non-neoplastic masses were aspergillus abscess (n = 1), sterile abscess (n = 1), and tubercular abscess (n = 1), aneurysm of left internal carotid artery (n = 1), and ruptured dermoid cyst (n = 1). All patients (except one) presented with headache and/or visual disturbance. Only one patient had acromegaly while most others had hypopituitarism. We describe detailed MRI characteristics of each of the lesion. Seven patients underwent trans-sphenoidal surgery. Post-operatively, five patients had permanent diabetes insipidus, while two patients died in early post-operative period.

Conclusion: Our series expand the differential diagnostic considerations of SSR lesions. Most of the rare SSR masses present with symptoms of mass effects and hypopituitarism. Except for some non-neoplastic lesions like sellar abscesses, aneurysms, and dermoid cysts which can have some specific imaging characteristics that can provide clue to pre-operative diagnosis, most of the other neoplastic masses have overlapping radiological features, and pre-operative suspicion remains difficult.

Keywords: abscess; aneurysm; astrocytoma; granular cell tumor; malignant peripheral nerve sheath tumor; sellar suprasellar region.

Figure 1

MRI features of cases 1, 2, and 3 (pituitary abscesses). Case 1 (sterile abscess): A1, hypointense on T1WI; A2, hyperintense on T2WI; A3, rim enhancement with loculations on post contrast image. Case 2 (tubercular abscess): B1, isointense on T1WI; B2, hyperintense on T2WI; B3, rim enhancement with shaggy borders on post contrast image. Case 3 (Aspergillus abscess): C1, isointensity on T1WI; C2, T2WI showing central area of intermediateintensity surrounded by hyperintensity (shown by arrowhead); C3, peripheral rim enhancement with extension of the lesion in sphenoid sinus (shown by yellow arrow); C4, 'target lesion' on diffusion weighted imaging (white arrow).

Figure 2

MRI features of cases 4 and 5 (non-infective, non-neoplastic SSR lesions). Case 4 (ruptured Dermoid cyst): A1, coronal T1WI showing heterogeneously hyperintense areas suggesting fat content; A2, mass is iso to hypointense on coronal T2WI; A3, sagittal T1WI showing multiple T1 hyperintensities in subarachnoid spaces (shown by yellow arrows) and also along left lateral ventricle (yellow asterisk in A1) suggestive of rupture of dermoid cyst; A4, axial DWI showing no restriction in the lesion. Case 5 (sellar aneurysm): B1, coronal T1WI showing heterogeneously isointense mass; B2, coronal T2WI showing areas of hypointensity on left superior aspect (flow voids, red arrows) and inferior aspect (white arrow head), probably due to organised blood in thrombus; B3, coronal postcontrast T1WI showing intense enhancement in left superior aspect of lesion (corresponding to flow void areas on T2WI) suggestive of patent lumen of aneurysm. Also note the non-enhancement in the rest of the mass, suggestive of thrombus; B4, left carotid artery angiogram on DSA showing inferomedially directed wide neck aneurysm (black arrow) of left supraclinoid ICA near the origin of ophthalmic artery.

Figure 3

Features of granular cell tumors (cases 6 and 7) on MRI imaging. Case 6: A1, coronal T1WI showinghomogenously isointense rounded sellarsuprasellarmass; A2, coronal T2WI showingmass to be heterogeneously isointense; A3, coronal T1WI post contrast image shows hyperenhancing mass. Note that the pituitary is not seen separately from the mass. Case 7: B1, coronal T1WI, irregularly shaped isointense sellar-suprasellar mass; B2, coronal T1WI post contrast image; B3, sagital T1WI post contrast image. Both show hypoenhancing mass as compared to normal pituitary, which is clearly seen separate from the mass.

Figure 4

Features of other neoplastic sellar masses (cases 8, 9, and 10) on MRI imaging. Case 8 (sellar astrocytoma): A1, coronal T1WI; A2, coronal T2WI, the sellar mass is solid, hyperintense on T1WI and iso-hypointense on T2WI (suggestive of acute haemorrhage); A3, coronal T1WI post contrast image; A4, sagittal T1WI post contrast image. Mass shows no further enhancement due to very high baseline intensity on T1WI. Also note the predominant sellar location of the mass. Case 9 (MPNST): B1, coronal T1WI; B2, coronal T2WI; B3, sagittal T1WI post contrast image. Well defined sellar-suprasellar mass is isointense on T1WI, hyperintense on T2WI, and shows homogenous intense enhancement on post contrast imaging. Case 10 (sellar metastasis): C, coronal T1WI post contrast image showing round predominantly suprasellar mass with heterogenous contrast enhancement, seen separate from pituitary.

Figure 5

Photomicrographs showing pathological features of case 3 (Aspergillus abscess) and cases 6 and 7 (Granular cell tumor). Case 3 (Aspergillus abscess): A, aggregates of septate branching filamentous fungi with adjacent degenerating neutrophils (H&E 400x); Case 6 (Granular cell tumor): B1, tumour showing polygonal cells with abundant eosinophilic granular cytoplasm and central located oval shaped nucleus (H&E 400x); B2, tumour cells are immunopositive for thyroid transcription factor 1 (TTF1 immunohistochemistry; 400x); Case 7 (granular cell tumor): C, clusters of large cells with abundant granular cytoplasm, small inconspicuous nuclei. Cells are separated by thin walled collapsed vascular channels.

Figure 6

Photomicrographs showing pathological features of case 9 (Malignant peripheral nerve sheath tumor) and case 10 (Metastasis from papillary thyroid carcinoma). Case 9 (malignant peripheral nerve sheath tumor): A1, tumor with moderate-high cellularity with spindle cells having focally palisading buckled nuclei (black arrowheads) and perivascular condensation of tumor cells (black arrow) (H&E 400x); A2, tumor showing high proliferative index (MIB-1 index-12%); Case 10 (metastasis from papillary thyroid carcinoma): B1, tumour showing conspicuous follicular/microfolicular architecture (H&E 200x) with typical nuclear clearing (as shown in the inset, H&E 400x); B2, tumour is immunopositive for TTF1 (immunohistochemistry; 400x), thus confirming the primary papillary thyroid carcinoma.