Case report

A 36-year-old woman (G3P2) presented to our center at 30 weeks of her pregnancy. Our ultrasound examination revealed a mass within the fetal skull adjacent to the left parietal bone. The mass was compressing and displacing the brain, cerebral ventricles and midline structures to the opposite side. The tumor was well demarcated with no apparent connection to the compressed brain. Color Doppler showed a rich vascularization of the tumor. The skull was slightly deformed. Location of the tumor and its characteristics described above were suggestive of a meningeal tumors. The MRI confirmed the ultrasonographic findings and the parents opted for termination of pregnancy. Pathological study found an extracerebral tumor localized between the parietal bone and brain. Histological and immunohistochemical study classified the tumor as the hemangiopericytoma.

Images 1, 2: 30 weeks of pregnancy; the images show transverse oblique scans of the fetal skull with an inhomogeneous hyperechoic lesion between the fetal skull adjacent to the left parietal bone. The tumor compresses the brain and cerebral ventricles. The skull is slightly deformed.

Image 3: 30 weeks of pregnancy; the image show transverse scan of the fetal skull with well vascularized tumorous mass between the left parietal bone and brain.

Images 4, 5: 30 weeks of pregnancy; the image 4 shows transverse gray scale ultrasonographic scan of the fetal skull with a tumorous lesion between the left parietal bone and brain, compressing the brain and ventricular system to the opposite side. The image 5 represents a fusion of the image 4 with the pathological specimen of the fetal brain, explaining the location of the tumorous mass histologically classified as hemangiopericytoma.

Images 6, 7: 30 weeks of pregnancy; the image 6 shows transverse color Doppler ultrasonographic scan of the fetal skull with a well vascularized tumorous lesion between the left parietal bone and brain, compressing the brain and ventricular system to the opposite side. The image 7 represents a fusion of the image 6 with the pathological specimen of the fetal brain, explaining the location of the tumorous mass histologically classified as hemangiopericytoma.

Images 8, 9: 30 weeks; the images show MRI representation of the tumorous mass within the fetal brain.

Images 10, 11: Pathological specimen showing the mass of hemangiopericytoma (arrows) compressing the brain (arrows). The mass of the tumor contains focuses of necrosis (arrow 1 on the image 10) and hemorrhages (arrow 2 on the image 10) indicating the fast growth of the tumor.

Images 12, 13: Histological specimens of the hemangiopericytoma.

Definition

Hemangiopericytomas represent spindle-celled, fast growing, richly vascularized mesenchymal tumors, arising from pericytes (cells of smooth muscles lying around small vessels). Benign and malignant forms have been described.

Origin

The hemangiopericytomas originate from pericytes of the blood vessels of the meninges.

Incidence

Rare; these tumors make up 2-4% of meningeal tumors and less than 1% of all intracranial tumors.

Classification

The World Health Organization (WHO) in 1979 originally categorized the hemangiopericytoma as meningeal tumors and included it among meningiomas, with a specific name "hemangiopericytic meningioma". In 1993 the WHO classification considered the hemangiopericytoma as an isolated entity, putting it among non-meningothelial "mesenchymal" group of tumors. In 2000, the WHO classification categorized the hemangiopericytoma as an entity of its own.

Ultrasound findings

Hemangiopericytoma appears as an extradural, hyperdense lesion adjacent to the skull, compressing and displacing the brain. Abnormal shape of the skull may be also present. The tumor is well demarcated, with no connection with the brain. Color Doppler examination of the tumor reveals quite a rich vascularization. The tumor usually appears in the third trimester of pregnancy.

MRI may be of help in the determination of the size, location and mutual relationships between the tumor and brain tissue.

Differential diagnosis

• Meningothelial meningioma (less aggressive) – this tumor has the same ultrasound appearance and it is not easy to distinguish between them prenatally. • Other brain tumors - may have different location and relation to the brain tissue.

Management

Termination of the pregnancy may be offered to the parents.

Treatment

Surgical resection with adjuvant radiotherapy increases local control rates, tumor-free survival and global survival. However, complete excision is possible only in 50-67% of cases. The operation is often complicated by bleeding due to the rich vascularization of the tumor. Neoadjuvant radiotherapy decreases the tumor size and reduces the risk of perioperative bleeding and surgical complications.

Pathology

The tumor consists of the spindle cells interwoven by rich vasculature. Immunohistochemistry should be performed in order to confirm the diagnosis.

Prognosis

Despite the surgical treatment, the local recurrence is common, with high risk of extra-cranial metastases.

References

1. Recurrent Intracranial Hemangiopericytoma with Multiple Bone Metastases: Case Report. Franca CAS, Vieira SL, Guizzardi MF, Klemz MR, Carvalho ACP, Penna ABRC. Applied Cancer Research 2008; 28(2):80-82.

2. Fetal meningeal hemangiopericytoma. Case report. Cavalheiro S, Sparapani FV, Moron AF, da Silva MC, Stávale JN. J Neurosurg. 2002 Nov;97(5):1217-20.

3. Fetal hemangiopericytoma with an associated cerebral anomaly. Hornoy P, Sonigo P, Fallet-Bianco C, Largiliere P, Teillac D, Gomes H, Uzan M, Brunelle F. Ultrasound Obstet Gynecol. 2005 Jul;26(1):81-5.

4. A Case of Malignant Hemangiopericytoma: An Immunohistochemical and Ultrastructural Study.  Sugisaki K, Tsuda T, Miyazaki E, Matsumoto T, Mizuki M. Respiration 1994;61:172-175.