January 2019 Case

Michael Pakdaman, MD, and Thomas Learch, MD

A 38-year-old female presented with a 9-month history of headaches and amenorrhea. Laboratory workup revealed low luteinizing hormone LH and follicle stimulating hormone FSH. Her past medical history includes irregular menses, remote history of melanoma excision from her thigh, and surgical removal of an ovarian cyst as a child. MRI of the pituitary was performed.

Magnetic resonance imaging [MRI] exam of the pituitary found the pituitary gland to be within normal limits in appearance but relatively small in size with a maximum height of approximately 3 mm. For a woman in the childbearing years this pituitary size was considered small. Additionally, a 13 x 13 x 13.2 mm homogeneously enhancing spherical mass was seen in the upper half of the infundibulum, which appeared to arise from the infundibulum itself and impinge upon the undersurface of the optic chiasm and third ventricle (Figure 1). Relative to cortex, the mass was iso/hypointense on T1 and isointense on T2-weighted images, and enhanced avidly and homogeneously after contrast administration (Figure 2). The lesion was not well appreciated on DWI or on ADC map (Figure 3).

Figure 1 A-D (below). Sagittal and coronal T1 pre- and post-contrast demonstrating a 13 x 13 mm spherical suprasellar mass in the upper half of the infundibulum that is slightly hypointense relative to cortex, with uniform avid enhancement. On Sagittal images, you can appreciate the mass impinging on the undersurface of the optic chiasm.

Figure 2 A-C (below). Axial T1 pre-contrast, Axial T2, and Axial T1 post-contrast images through the pituitary fossa. The mass was iso/hypointense relative to cortex on T1 and isointense on T2-weighted images, and avidly enhancing.

Figure 3 A-B (below). No diffusion restriction is noted on the b1000 images (A) and there is no dark spot on the ADC map (B).

The patient underwent endoscopic transsphenoidal resection of the mass using stereotactic navigation. Intraoperatively, a soft, fleshy, yellowish tumor with a vascular capsule was identified in the suprasellar space arising directly from the pituitary stalk, grossly reminiscent of a pituicytoma. Gross total resection of the primary lesion was obtained, and the pituitary stalk was sectioned as a component of tumor removal. Partial resection of pituitary gland was also performed for better exposure to the lesion.

Gross inspection of the mass revealed a 6 x 3 x 3 mm fragment of red-tan soft tissue. Histopathologic analysis of hematoxylin and eosin [H & E] stained sections showed a neoplasm composed of vascular channels associated with foamy stromal cells, containing clear cytoplasmic vacuoles (Figure 3A). No necrosis or mitotic activity was seen. Immunohistochemical analysis revealed positive staining for S100 (Figure 3B), neuron-specific enolase [NSE] (Figure 3C) and galectin-3 (Figure 3D). The tumor was negative for meningioma and spindle cell oncocytoma marker epithelial membrane antigen [EMA], as well as chordoid glioma of the third ventricle and pituicytoma marker glial fibrillary acidic protein [GFAP]. Based on the microscopic and immunohistochemical findings, a diagnosis of hemangioblastoma was established.

Figure 4 A-D (below). (A) H&E stained section discloses vascularized tumor with abundance of vacuolated foamy cells (*). (B) Positive red chromagen staining for s100 (**). (C) Positive red chromagen on NSE stain (***). (D) Positive red chromagen on galectin 3 stain (****).

This is a case of suprasellar hemangioblastoma in a patient without VHL, which, based on close association with the infundibulum and avid enhancement, strongly resembled a pituicytoma.

Hemangioblastomas are highly vascular tumors found in the central nervous system [CNS], most commonly detected in the posterior fossa and cervical spinal cord, but also seen in retina (Kassardjian, Macdonald, & Munoz, 2014). Hemangioblastomas are uncommon, accounting for approximately 3% of CNS tumors (Neumann et al., 1989). They are less commonly sporadic, and rarely occur outside of the posterior fossa. Only a small handful of cases have been reported of supratentorial hemangioblastoma without von Hippel-Lindau Disease [VHL] (Pandey, Sharma, Pandey, Kumar, & Kumar, 2016). Of these, only four cases of hemangioblastoma arising from the pituitary infundibulum have been reported (Schar, Vajtai, Sahli, & Seiler, 2011).

Hemangioblastomas of the CNS are best visualized on gadolinium-enhanced MRI. While MRI findings are not pathognomonic, hemangioblastomas are typically seen on MRI as a cystic mass with an enhancing mural nodule, most commonly in the posterior fossa. The nodule is dark on T1-weighted images, bright on T2-weighted images, and homogeneously enhancing (Bamps et al., 2013; Li et al., 2015; Pandey et al., 2016). Infrequently hemangioblastomas may be solid, with peripheral enhancement, or cystic with an enhancing wall. Neuroangiography reveals a highly vascular tumor within an avascular cyst, with feeding vessels from dural arteries (Pandey et al., 2016)

Histopathologically, hemangioblastomas are highly vascular tumors consisting of numerous capillaries and stromal cells (Innus & Patterson, 2007). They are seen as an extensive vascular network with neoplastic stromal cells featuring nuclear hyperchromasia and degenerative atypia (Innus & Patterson, 2007). They are commonly positive for CD34, NSE (Li et al., 2015), S100 protein (Cheng, Chu, Xu, & Wang, 2015; Epari et al., 2014), and galectin-3 (Al-Salam, Al-Salam, & Al Ashari, 2013).

Definitive management of CNS hemangioblastoma is by surgical resection of the enhancing nodule. If the location of the mass is not amenable to excision, then stereotactic surgery and radiation therapy are non-definitive alternatives. Additionally, as hemangioblastomas in VHL can often recur, surgery is reserved for symptomatic lesions.

This is a sporadic case of solitary, non-cystic hemangioblastoma arising from the infundibulum and appearing quite similar to a pituicytoma and chordoid glioma. This demonstrates that, while rare, hemangioblastomas should be considered on the differential diagnosis for an avidly enhancing suprasellar mass.

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