Hemangiopericytoma

Abstract

The management of patients harboring hemangiopericytomas (HPCs) (cranial or spinal) is a partially answered challenge, as these lesions portray an aggressive behavior. Resection remains the initial treatment option, facilitating histological diagnosis and providing relief of tumor related mass effect. Patients receiving surgery alone or surgery and radiotherapy showed improved OS and PFS as compared to biopsy alone (p=0.01 and p=0.02, respectively). Yet, in many cases patient related comorbidities, as well as tumor related parameters (adjacent neurovascular structures, skull-base location) preclude complete resection. Radiotherapy or stereotactic radiosurgery (SRS) was not shown to impact OS in HPC's patients (p=0.691). The benefits of SRS / EBRT are clearly limited to improved local tumor volume control and neurologic function, not affecting distant metastases or ENM development. We present a short discussion on HPC's of the head and spine, reviewing current treatment paradigms, focusing our discussion on available evidence regarding the role of SRS for upfront, part of adoptive hybrid surgery approach or for recurrent HPC's. SRS provides acceptable rates of local tumor volume control coupled with treatment safety and a patient friendly apparatus and procedure. Single session SRS is most effective for lesions measuring <2cm in their largest diameter or approximately 10 cm3 volume, with prescription doses of at least 15 Gy. SRS was shown in addition, to lead to neurological stability or improvement in most patients. The management of recurrent intracranial HPC's disease must be tailored to the size and location of a specific lesion and to the overall systemic disease burden. In general, recurrent HPC lesions measuring ≥3cm in largest diameter in potentially resectable locations and a relatively fit patient are best treated by extirpation followed by adjuvant SRS (AHS approach). Smaller recurrent HPC lesions measuring <3 cm in greatest diameter can be adequately controlled with SRS alone. In those suffering from advanced, symptomatic ENM, radiotherapy may also play an important palliative role. A key component to patient care lies in vigilant clinical and radiographic follow-up visit schedule. Close follow-up MR imaging unequivocally leads to early detection of tumor recurrence or distant neural metastases formation.