Unusual suprasellar vascular malformation mimicking a tumour in a girl presenting with subacute vision loss

Description

A teenage girl presented for the evaluation of 7 months of peripheral vision loss and concomitant intermittent headaches. Neurological examination identified left homonymous hemianopsia and pale optic nerves bilaterally on funduscopic exam. Brain MRI revealed a minimally enhancing, T1-hyperintense solid and cystic suprasellar–chiasmatic–hypothalamic mass measuring 2.4 cm×2.7 cm×1.4 cm in anteroposterior, transverse and craniocaudal dimensions that extended into the interpeduncular cistern and exerted mild mass effect on the right cerebral peduncle (figure 1A, B). A non-enhancing, mostly homogeneous T1-hyperintense cystic and haemorrhagic component was detected extending along the right perimesencephalic cistern (figure 1C, D). The T1 hyperintensity of the solid foci and homogeneously hyperechoic density on comparison CT (figure 1E, F) were considered reflective of proteinaceous or haemorrhagic debris. No areas of abnormally reduced diffusion were detected; the infundibulum and pituitary were distinct and normally enhancing, and the orbits appeared unremarkable. No significant surrounding vasogenic oedema was appreciated. The neuroradiographic differential diagnosis included craniopharyngioma, optic pathway glioma, germ cell tumour, Langerhans’ cell histiocytosis or lymphoma. The patient underwent surgery where intraoperative frozen section was consistent with a vascular lesion with thin-walled vessels, many of which were dilated or collapsed (figure 2A–C), and several of which had the appearance of dilated lymphatic channels. A gross total resection was achieved during the same operation, and permanent sections revealed focally organising thrombi and dystrophic calcifications, in addition to some fibrous tissue interspersing the lesion’s vascularity. CD-31 immunohistochemistry affirmed an abundance of thin-walled vessels (figure 2D), some of which also were positive by immunohistochemistry for D2-40 (not shown). These neuropathological features were considered most consistent with a combined lymphatic–venous malformation. Postoperative evaluation demonstrated a stable neurological exam without improvements in vision at 6 months of postsurgical follow-up.

Figure 1.

Neuroimaging features of a suprasellar lymphatic–venous malformation mimicking a brain tumour. T1-weighted, pregadolinium brain MRI shows a hyperintense mass tracking along the right optic tract and perimesencephalic cistern (A, B) (arrows) with patchy enhancement on post-T1 gadolinium sequences (C, D) (arrows). CT findings demonstrate a large suprasellar hyperdense mass with dystrophic calcifications (E, F) (arrows).

Figure 2.

Neuropathological features of a central nervous system lymphatic–venous malformation. H&E staining shows thin-walled vessels of a vascular malformation with multiple organised thrombi, ×40 (A), dilated lymphatic vessels (arrows), ×40 (B), vein dilatation and organised thrombi, ×40 (C). CD31 immunohistochemical stain highlights malformed vessels, ×100 (D).

Lymphatic–venous malformations are rare lesions that arise congenitally from aberrant development of the embryonic vasculature.^1–4 These ‘slow-flow’ malformations customarily grow pari passu alongside the developing child and can thus elude clinical detection, often for years.^{1 5–7} However, insults to these lesions, such as internal haemorrhage, trauma or infection, can incite spontaneous enlargement, which consequently results in the secondary emergence of acute or subacute clinical symptomatology.^8–10 Indeed, belying the dichotomous histological classification of vascular ‘malformations’ as proliferatively distinct from vascular ‘tumours’,^{1 6 11} our case demonstrates that benign vascular lesions can radiographically manifest indistinguishably from tumours. In such cases, CT or MRI angiography may be helpful in distinguishing tumour from a vascular malformation and was not performed in this patient prior to surgery. Although familial patterns of vascular malformations can arise due to mutations of particular genes,^{1 12} or vascular malformations can appear as one component within a broader syndrome,¹ our patient did not exhibit other vascular abnormalities on head and neck imaging, suggesting stochastic genesis was the more likely aetiology of her anomalous malformation. Future investigation of lymphatic–venous malformations will be important to refine our understanding of the development of these lesions in the brain. Our case of a lymphatic–venous malformation mimicking the appearance of a tumour adds to the differential diagnosis of unusual suprasellar lesions.

Learning points.

• Combined lymphatic–venous malformations are congenital lesions that arise from aberrant patterning of vasculature during embryogenesis.

• Spontaneous and rapid growth of central nervous system vascular malformations may present with acute or subacute neurological deficits including visual field defects, diplopia, papilloedema and optic nerve sheath enlargement that may mimic the appearance of a tumour in neuroimaging.

• MRI or CT angiography may be helpful in distinguishing atypical vascular malformations from tumours.

Ethics statements

Patient consent for publication

Consent obtained from parent(s)/guardian(s).