Hemangiopericytoma: A clinicopathologic study and long‐term followup of 60 patients

Abstract

The clinical courses of 60 patients with hemangiopericytoma of the somatic soft tissues are summarized in this retrospective study. The tumors were subjected to a comparative histologic review and classified as benign (12 lesions), borderline malignant (16 lesions), and malignant (32 lesions). Tumors with 1 mitotic figure per 10 high‐power fields and slight cellular anaplasia or 1 mitotic figure per 20 high‐power fields and moderate cellular anaplasia may be expected to follow a malignant clinical course. Six of the 16 tumors with these microscopic features (borderline lesions) metastasized (37.5%), and 6 exhibited local recurrences after excision. Of the 32 malignant tumors, 25 (78%) metastasized. Twenty‐three patients with malignant tumors were followed for more than 5 years or until death from tumor, and only one patient was alive and free of disease. Fifteen of the 23 patients experienced one of more local recurrences. None of the benign tumors metastasized. Surgical ablation of hemangiopericytoma is, in our experience, the only satisfactory method of treatment. Amputation of an extremity need be done only when the location of the lesion precludes a wide local excision. Local recurrent tumor was experienced by 22 patients after an inadequate local excision. Long‐term follow‐up is recommended because metastasis became apparent in 11% of patients with malignant tumors and 7% with borderline tumors after 5 “disease‐free” years.

Solitary fibrous tumor: a clinicopathological study of 110 cases and proposed risk assessment model

“…Historically, hemangiopericytomas have been reported to have a worse prognosis than solitary fibrous tumor, with 5-and 10-year hemangiopericytoma survival rates as low as 59 and 47-70%, respectively, 3,15 and up to 48% disease-specific mortality. 16 In pleural solitary fibrous tumor, recurrence and mortality are reportedly predicted by both histology and resectability; typically, benign pedunculated tumors excised with clear margins have a recurrence rate of 2%, while sessile malignant solitary fibrous tumors may recur up to 63% of the time, resulting in a 30% mortality rate. 8,17 Extrathoracic solitary fibrous tumors behave similarly; diseasespecific death accounted for only 3 patients in one series of 75 patients 10 and no patients in a series of 24 cases with up to 20-year follow-up.…”

“…19 However, older series also found higher metastatic rates in hemangiopericytoma and pleural solitary fibrous tumor-from 18 to 50%. 2,3,16,20 This variability may be due in part to differences in follow-up time as well as referral bias. Adequate follow-up time is required to determine metastatic frequency.…”

“…McMaster et al found that B10% of metastases occurred after 5 event-free years, while Vallat-Decouvelaere et al found that 40% of metastases occurred after 5 years. 11,16 Consequently, studies with short followup may not accurately reflect metastatic potential of tumors with malignant histological features, 7 although even in studies with longer follow-up, tumors defined as malignant using historical criteria did not metastasize. 19 In our study, 50% of metastases occurred after 36 months, but could present up to 19 years after initial resection.…”

“…In our study, moderate pleomorphism and cellularity were the norm in classic solitary fibrous tumors, while hemangiopericytomatous variants were more likely to have minimal pleomorphism, but high cellularity. Previous reports focus on cellularity in solitary fibrous tumor 10 or pleomorphism in hemangiopericytoma 16 together with mitotic activity as the criteria for malignancy. One instance in which cellularity and pleomorphism can be significant is in poorly differentiated areas (dedifferentiation), which occurs as an undifferentiated highgrade anaplastic sarcoma sharply demarcated from areas of conventional solitary fibrous tumor.…”

Conventional hemangiopericytoma

“…Two other studies of conventional HPC, conducted before the routine use of immunohistochemical techniques to identify cell types of soft tissue sarcomas, are revealing. In an evaluation of 60 patients, McMaster et al 18 found that 48% had died of disease. Of the19 patients reported by Auguste et al, 19 53% developed pulmonary metastases; the overall survivals were 59% and 47% at 5 and 10 years, respectively.…”