Stathis Philippou, Nils-Claudius Gellrich*
Hemangiopericytomaof the head and neck region
Department of Pathology, and *Department of Oral and Maxillofacial Surgery, Ruhr University Bochum, Germany
A clinical and morphological study of three cases S. Philippou, N.-C. Gellrich: Hemangiopericytoma of the head and neck region. A clinical and morphological study of three cases. Int. J. Oral Maxillofac. Surg. 1992; 21: 9~103. Abstract. Whereas the morphological picture allows classification of malignant hemangiopericytomas with great accuracy, classification of hemangiopericytomas exhibiting a histologically and cytologically benign picture can be difficult. Three hemangiopericytomas of the head could be studied in detail both clinically and morphologically. Inspire of light, scanning and transmission electron microscopic, immunohistochemical and electron microscopic studies no reliable histological criteria indicative of the biological pattern of so-called "benign" hemangiopericytoma could be found. Thus, it appears appropriate to consider all hemangiopericytomas as potentially malignant. Zusammenfassung. W/ihrend aufgrund des morphologischen Bildes die Einteilung der malignen H/imangioperizytome mit groBer Sicherheit erfolgen kann, ist die Klassifizierung der H/imangioperizytomen, die histo- und zytologisch ein gutartiges Bild aufweisen, im Einzelfall mit Probleme verbunden. Drei H/imangioperizytome aus dem Kopfbereich wurden eingehend klinisch und morphologisch untersucht. Es konnten keine sichere histologische Kriterien erarbeitet werden, die einen Hinweis auf das biologische Verhalten von sogenannten "gutartigen" H/imangioperizytomen ergeben. Aus diesem Grund erscheint es sinnvoll, alle H/imangioperizytome als potentiell maligne anzusehen.
Hemangiopericytomas are rare mesenchymal tumors consisting of diffuse elongated cells arising from Zimmerman's pericytes enclosed in reticulin fibres and often collapsed vascular spaces. The tumors are usually detected by angiography, CT scanning or MRI. The definitive diagnosis, however, can only be established by histological examination. The differentiation between benign and malignant hemangiopericytomas can be difficult, as histologically and cytologically benign-appearing hemangiopericytomas can prove to be malignant. Metastases of seemingly benign tumors may appear years or decades later. The treatment of choice is complete surgical excision of the tumor. Due to the anatomical configuration complete excision may often not be feasible. In those cases postoperative radiotherapy is indicated, whereas adjuvant, cytostatic therapy should be reserved for those patients in whom metastases are
evident. In the last 17 years 3 hemangiopericytomas of the head and neck area were diagnosed and studied both clinically and morphologically. Material and method
The clinical data of the patients are presented in Tables 1 and 2. In all patients microscopic, histochemical and immunohistochemical examination of the formalin-fixed surgical re-
Key words: hemangiopericytoma; ultrastructure; immunocytochemistry. Accepted for publication 4 December 1991
section material was performed. The paraffin-embedded material was stained with hematoxylin-eosin, Elastica-van Gieson, PAS and Gomori's silver stain. Immunohistochemical reactions to demonstrate vimentin (VIM), alpha 1-antitrypsin (ATT), alpha 1-antichymotrypsin (ATCT), desmin (DES) and factor VIII-related antigen (CAMON) were performed using the PAP-method. Glutaraldehyde-fixed tumor tissue was embedded in Epon 812 and in LR-white for transmission electron microscopy (Zeiss,
Table 1 Age Patient Sex
Tumor site/ diameter
1
27 yrs male
infratemporal, 4 can,
2
56 yrs female
frontobasilar, 3 cm
3
53 yrs female
infratemporal, 8 cm
Preliminary diagnoses
Months till verification of diagnosis
Clinical manifestations
parotid adenoma
5
painless swelling
fibrolipoma
2
slow growing soft, painless mass, ophthalmol, complications, since 2 yrs
?
10
slow growing resilient mass
100
Philippou and Gellrich
Table 2. Patient
Intraoperative findings
Therapy
1
pseudoencapsulation; osteolysis of medial surface of ascending ramus; moderate bleeding
Surgery(preop.embolisation); irradiation (60Gy)
naso-basilar bone arrosion; moderate bleeding
Surgery; irradiation (60Gy)
pseudoencapsulation; osteolysis of medial sur- Surgery; irradiation (60Gy); face of ascending ramus; max. and mand. nerve chemotherapy (Haloxan) involvement; severe bleeding
EM10) and immunoelectron microscopy. The postembedding procedure for immunoelectron microscopy was applie& Antibodies reacting with VIM, DES, Actin (ACT) and ATCT were used and subsequently marked with colloidal gold. Some formalin-fixed specimens underwent serial alcohol dehydration, ascending Fryon series and subsequent critical point drying. The material was then applied to an aluminum plate and spattered with gold. Scanning electron microscopy was performed with a Zeiss scanning electron microscope (DSM 950). Results
The first 2 cases presented a similar morphological microscopic picture, showing abundant cells. In some areas more than 8 mitoses/10 HPF (Fig. la) could be demonstrated. There were nu-
merous zones of necrosis and hemorrhage. Immunohistochemical studies showed a highly positive reaction for VIM (Fig. 2a) and a focal, moderate, positive ATT (Fig. 2b) and ATCT reaction. The DES reaction was negative. Immunocytoreactivity for factor VIIIrelated antigen was positive only in the endothelial cells of the capillaries. A uniform histological picture was found in all areas of the tumor examined in the 3rd patient. Cells were only moderately abundant and mitoses were sparse (Fig. l b). Only scattered, minute, circumscribed hemorrhages and necrosis areas were seen. A single endothelial cell layer with a marked basal lamina was seen at transmission electron microscopy. Below the basal lamina pericytes were closely formed, and between the pericy-
Recurrence
'86 R. lat. orbit '88 R. cranial orbit infiltration of eyeball '89 L. lat. orbit L. infratemporal fossa '90 retroperitoneum L. infratemporal fossa L. lat. orbit "73 R. infratemporal fossa '74 R. infratemporal fessa '76 R. retromax, space '79 lung metastasis '80 R. submand, space; thyroid gland '82 R. external meatus '83 R. retromax, and submand, space '84 liver metastasis, exitus
tes were polyglycan-rich, basal laminalike colloidal substance and striated microfibrils (Fig. 3a) Within the cytoplasm microfilamentary structures (Fig. 3a), individual vesicles and focally welldeveloped endoplasmic reticulum could be found. Immunogold marking of the intracytoplasmic microfilaments with VIM was positive (Fig. 3b) without background staining and with a positive endogenous reaction. In a few individual tumor cells a positive ACT reaction occurred with the intracytoplasmatic microfilamentary structures. Scanning electron microscopy facilitated a 3-dimensional demonstration of the internal structure of the tumor. Below the capillary endothelium the basal lamina with pericytes lying immediately beneath could be demonstrated. The cytoplasmic extensions reached the
Fig. la. Malignant hemangiopericytoma (Cases 1 and 2) with several mitoses (arrow). H&E. x 350. Fig. lb. "Benign"-appearing hemangiopericytoma without mitoses (Case 3). H&E. x 330.
Hemangioperieytoma
101
Fig. 2a. Positive tumor immunocytoreactivity with the antibody vimentin, x 800. Fig. 2b. Positive tumor immunocytoreactivity with the antibody alpha l-antitrypsin, x 850.
Fig. 3a. Sectioned capillary with a regular endothelial cell. Immediately beneath the basal lamina (long arrow) tumor cells with proteoglycanrich colloidal substance and striated microfibrils in between. Microfilamentary structures (short arrow) within the cytoplasm of the tumor cells. Transmission electron micrograph, x 12000. Fig. 3b. Intracytoplasmic microfilamentary structures demonstrating positive immunocytoreactivity for vimentin by the immunogold method (short arrow) with negative background and without reactivity of the tumor cell nuclei (long arrow). Transmission electron micrograph, x 75000.
basal lamina (Fig. 4a). Some of the pericytes had a bossed surface. The reticulin fibres arranged in between showed focal areas with a club-like surface and marked network-like branching. They enclosed individual tumor cells or small tumor cell groups, and in between were capillaries filled with erythrocytes (Fig. 4b). Discussion
The differential diagnosis between benign and malignant hemangiopericytomas is often considered difficult. Malignant hemangiopericytomas can be diagnosed with great accuracy by application of the criteria of ENZINGER & SMITH (4). The classification of heman-
giopericytomas exhibiting a histologically and cytologically benign picture, however, can be difficult. These tumors can recur years or decades later - latency periods up to 33 years have been reported (8). Late metastases have also been reported. SHIN et al. (9) presented a patient in whom a metastasis occurred 28 years after initial diagnosis. Patient 3 presents a similar pattern, in that the tumor appeared to be benign both histo- and cytologically, but caused the patient's death 16 years after the first operation from ensuing lung and liver metastases. Inspite of light, scanning and transmission electron microscopy as well as immunohistochemical and electron microscopical studies no definite histological criteria indicative of the
biological pattern of so-called "benign" hemangiopericytomas could be established. The occurrence of metastases even after many years makes the existence of benign hemangiopericytomas questionable. It appears appropriate to consider all hemangiopericytomas as potentially malignant. The clinical course alone determines whether or not the tumor should be called benign or malignant. An observation period of at least 10 years is required before a fairly reliable statement can be made about the behavior of the tumor. Trauma has also been discussed as a cause of hemangiopericytomas (5). In 2 of our cases trauma was mentioned in the history. The treatment of choice is complete
102
Philippou and Gellrich
Fig. 4a. Below the basal lamina (white arrows) of the endothelial cells reticulin fibres surrounding tumor cells with intact cytoplasmic extensions (black arrows) reaching the basal lamina. Scanning electron micrograph, x 2932. Fig. 4b. Root-like branched reticulin fibres (long arrow) with tumor cells lying in between and capillary vessels filled with erythrocytes (short arrow). Scanning electron micrograph, x 2000.
Fig. 5a. Preoperative angiography of the infratemporal tumor vascular bed subsequent to embolisation with Terbal particles and platinum minispirals (arrow). Fig. 5b. Contrast medium (Gadolinium) - enhanced magnetic resonance tomograph in AP projection with distinctly depicted tumor (arrow) involving the cranial base.
surgical excision. Radical removal of the tumor at the cranial bone is not always possible. Preoperative angiography with simultaneous embolisation via micro particles (e.g. Terbal 10-140/~) or platinum minispirals (Fig. 5a) may be helpful in reducing the size of the tumor before surgery, as well as the risk of intraoperative hemorrhage. The chance of intraoperative distribution of tumor cells is also diminished. Postoperative radiotherapy is recommended at least in cases of incomplete tumor removal, although these tumors are considered to be fairly resistant to radiotherapy (2). In the cases presented the primary tumor or the recurrence was treated with
50-60 Gy. Nevertheless, the tumor metastasized in 2 of the patients after 11 and 7 years. If surgical and radiotherapeutic means are exhausted, chemotherapy may be considered. Positive results are reported only for adriamycin alone or in combination with cyclophosphamid, vincristin, DTIC, methotrexat or actinomycin D (3, 7, 11). Some authors consider hemangiopericytomas to be chemotherapy-resistant (1, 6, 10). Lifelong follow-up of patients with hemangiopericytomas is mandatory. Magnetic resonance tomography is the preferred diagnostic aid since this is the most sensitive procedure for demonstrating mesenchymal neoplasms (Fig.
5b). Computerized tomography should be used if bone involvement is to be ruled out. No antibodies specific to hemangiopericytoma are available. In all 3 cases examined the VIM-reaction was positive, showing the mesenchymal character of this tumor. The ATT and ATCT reaction was positive in only a few tumor cells. This reaction is probably indicative of a phagocytic potential of the pericytes. The negative DES reaction in all cases examined could possibly be due to fixation of the material. The immunoelectron microscopic demonstration of ACT in individual tumor cells in the vicinity of the intracytoplasmic microfilamentary structures, which are also positive for VIM in immunoelectron microscopy, is probably based on the contractile character of the cell of origin. The histological studies can be significantly complemented by scanning and transmission electron microscopy, as well as immunohistochemistry and electron microscopy. None of the methods used, however, is reliable enough to state with certainty whether the tumor is benign or malignant.
References 1. ATKINSDN JB, MAHOURGH, ISAACSH,
ORTEGAJA. Hemangiopericytoma in infants and children. Am J Surg 1984: 148: 372-4. 2. BACKWINKELK, DIDDAMMSJA. Heman-
giopericytoma. Report of a case and comprehensive review of the literature. Cancer 1970: 25: 896-901. 3. BEADLEGF, HILLCOATBL. Treatment of
Hemangiopericytoma advanced malignant hemangiopericytoma with combination adriamycin and DTIC: a report of four cases. J Surg Oncol 1983: 22: 167-70. 4. ENZINGERFM, SMITHBH. Hemangiopericytoma. An analysis of 106 cases. Hum Pathol 1976: 7: 61-82. 5. GHUSSENF, NAGELK. Klinik und Therapie des H/imangiopericytoms. Schweiz Med Wochenschr 1981: 111:385 8. 6. McMASTER MJ, SOULEEH, IvIYs JC. Hemangiopericytoma. Long-term followup of 60 patients. Cancer 1975: 36: 2232~44. 7. NATHANSON DS. Preoperative chemo-
therapy and irradiation in the treatment of soft tissue sarcomas of the lower extremities: preliminary report of experience at Henry Ford Hospital. Henry Ford Hosp Med J 1984: 32" 31-8. 8. RICE CD, KERSTEN RC, MRAK RE. An orbital hemangiopericytoma recurrent after 33 years. Arch Ophthalmol 1989: 107: 552-6. 9. SHIN MS, KOEHLER RE, STANLEY R J, BARTONJC, HO K-J. Malignant hemangiopericytoma: computed tomography and magnetic resonance imaging. J Comput Tomogr 1987: 11:297 300.
103
10. WEBERBP, SCHRADERM, INNIGERR. Maligne H~mangiopericytome in KopfHals-Bereich. HNO 1990: 38: 326-33. 11. WONG PP, YAGODAA. Chemotherapy of malignant hemangiopericytoma. Cancer 1978: 41: 1256-60. Address:
Dr. S. Philippou Department of Pathology Ruhr University Bochum Universitgitsstrafle 150 4630 Bochum 1 Germany
Hemangiopericytomaof the head and neck region
Department of Pathology, and *Department of Oral and Maxillofacial Surgery, Ruhr University Bochum, Germany
A clinical and morphological study of three cases S. Philippou, N.-C. Gellrich: Hemangiopericytoma of the head and neck region. A clinical and morphological study of three cases. Int. J. Oral Maxillofac. Surg. 1992; 21: 9~103. Abstract. Whereas the morphological picture allows classification of malignant hemangiopericytomas with great accuracy, classification of hemangiopericytomas exhibiting a histologically and cytologically benign picture can be difficult. Three hemangiopericytomas of the head could be studied in detail both clinically and morphologically. Inspire of light, scanning and transmission electron microscopic, immunohistochemical and electron microscopic studies no reliable histological criteria indicative of the biological pattern of so-called "benign" hemangiopericytoma could be found. Thus, it appears appropriate to consider all hemangiopericytomas as potentially malignant. Zusammenfassung. W/ihrend aufgrund des morphologischen Bildes die Einteilung der malignen H/imangioperizytome mit groBer Sicherheit erfolgen kann, ist die Klassifizierung der H/imangioperizytomen, die histo- und zytologisch ein gutartiges Bild aufweisen, im Einzelfall mit Probleme verbunden. Drei H/imangioperizytome aus dem Kopfbereich wurden eingehend klinisch und morphologisch untersucht. Es konnten keine sichere histologische Kriterien erarbeitet werden, die einen Hinweis auf das biologische Verhalten von sogenannten "gutartigen" H/imangioperizytomen ergeben. Aus diesem Grund erscheint es sinnvoll, alle H/imangioperizytome als potentiell maligne anzusehen.
Hemangiopericytomas are rare mesenchymal tumors consisting of diffuse elongated cells arising from Zimmerman's pericytes enclosed in reticulin fibres and often collapsed vascular spaces. The tumors are usually detected by angiography, CT scanning or MRI. The definitive diagnosis, however, can only be established by histological examination. The differentiation between benign and malignant hemangiopericytomas can be difficult, as histologically and cytologically benign-appearing hemangiopericytomas can prove to be malignant. Metastases of seemingly benign tumors may appear years or decades later. The treatment of choice is complete surgical excision of the tumor. Due to the anatomical configuration complete excision may often not be feasible. In those cases postoperative radiotherapy is indicated, whereas adjuvant, cytostatic therapy should be reserved for those patients in whom metastases are
evident. In the last 17 years 3 hemangiopericytomas of the head and neck area were diagnosed and studied both clinically and morphologically. Material and method
The clinical data of the patients are presented in Tables 1 and 2. In all patients microscopic, histochemical and immunohistochemical examination of the formalin-fixed surgical re-
Key words: hemangiopericytoma; ultrastructure; immunocytochemistry. Accepted for publication 4 December 1991
section material was performed. The paraffin-embedded material was stained with hematoxylin-eosin, Elastica-van Gieson, PAS and Gomori's silver stain. Immunohistochemical reactions to demonstrate vimentin (VIM), alpha 1-antitrypsin (ATT), alpha 1-antichymotrypsin (ATCT), desmin (DES) and factor VIII-related antigen (CAMON) were performed using the PAP-method. Glutaraldehyde-fixed tumor tissue was embedded in Epon 812 and in LR-white for transmission electron microscopy (Zeiss,
Table 1 Age Patient Sex
Tumor site/ diameter
1
27 yrs male
infratemporal, 4 can,
2
56 yrs female
frontobasilar, 3 cm
3
53 yrs female
infratemporal, 8 cm
Preliminary diagnoses
Months till verification of diagnosis
Clinical manifestations
parotid adenoma
5
painless swelling
fibrolipoma
2
slow growing soft, painless mass, ophthalmol, complications, since 2 yrs
?
10
slow growing resilient mass
100
Philippou and Gellrich
Table 2. Patient
Intraoperative findings
Therapy
1
pseudoencapsulation; osteolysis of medial surface of ascending ramus; moderate bleeding
Surgery(preop.embolisation); irradiation (60Gy)
naso-basilar bone arrosion; moderate bleeding
Surgery; irradiation (60Gy)
pseudoencapsulation; osteolysis of medial sur- Surgery; irradiation (60Gy); face of ascending ramus; max. and mand. nerve chemotherapy (Haloxan) involvement; severe bleeding
EM10) and immunoelectron microscopy. The postembedding procedure for immunoelectron microscopy was applie& Antibodies reacting with VIM, DES, Actin (ACT) and ATCT were used and subsequently marked with colloidal gold. Some formalin-fixed specimens underwent serial alcohol dehydration, ascending Fryon series and subsequent critical point drying. The material was then applied to an aluminum plate and spattered with gold. Scanning electron microscopy was performed with a Zeiss scanning electron microscope (DSM 950). Results
The first 2 cases presented a similar morphological microscopic picture, showing abundant cells. In some areas more than 8 mitoses/10 HPF (Fig. la) could be demonstrated. There were nu-
merous zones of necrosis and hemorrhage. Immunohistochemical studies showed a highly positive reaction for VIM (Fig. 2a) and a focal, moderate, positive ATT (Fig. 2b) and ATCT reaction. The DES reaction was negative. Immunocytoreactivity for factor VIIIrelated antigen was positive only in the endothelial cells of the capillaries. A uniform histological picture was found in all areas of the tumor examined in the 3rd patient. Cells were only moderately abundant and mitoses were sparse (Fig. l b). Only scattered, minute, circumscribed hemorrhages and necrosis areas were seen. A single endothelial cell layer with a marked basal lamina was seen at transmission electron microscopy. Below the basal lamina pericytes were closely formed, and between the pericy-
Recurrence
'86 R. lat. orbit '88 R. cranial orbit infiltration of eyeball '89 L. lat. orbit L. infratemporal fossa '90 retroperitoneum L. infratemporal fossa L. lat. orbit "73 R. infratemporal fossa '74 R. infratemporal fessa '76 R. retromax, space '79 lung metastasis '80 R. submand, space; thyroid gland '82 R. external meatus '83 R. retromax, and submand, space '84 liver metastasis, exitus
tes were polyglycan-rich, basal laminalike colloidal substance and striated microfibrils (Fig. 3a) Within the cytoplasm microfilamentary structures (Fig. 3a), individual vesicles and focally welldeveloped endoplasmic reticulum could be found. Immunogold marking of the intracytoplasmic microfilaments with VIM was positive (Fig. 3b) without background staining and with a positive endogenous reaction. In a few individual tumor cells a positive ACT reaction occurred with the intracytoplasmatic microfilamentary structures. Scanning electron microscopy facilitated a 3-dimensional demonstration of the internal structure of the tumor. Below the capillary endothelium the basal lamina with pericytes lying immediately beneath could be demonstrated. The cytoplasmic extensions reached the
Fig. la. Malignant hemangiopericytoma (Cases 1 and 2) with several mitoses (arrow). H&E. x 350. Fig. lb. "Benign"-appearing hemangiopericytoma without mitoses (Case 3). H&E. x 330.
Hemangioperieytoma
101
Fig. 2a. Positive tumor immunocytoreactivity with the antibody vimentin, x 800. Fig. 2b. Positive tumor immunocytoreactivity with the antibody alpha l-antitrypsin, x 850.
Fig. 3a. Sectioned capillary with a regular endothelial cell. Immediately beneath the basal lamina (long arrow) tumor cells with proteoglycanrich colloidal substance and striated microfibrils in between. Microfilamentary structures (short arrow) within the cytoplasm of the tumor cells. Transmission electron micrograph, x 12000. Fig. 3b. Intracytoplasmic microfilamentary structures demonstrating positive immunocytoreactivity for vimentin by the immunogold method (short arrow) with negative background and without reactivity of the tumor cell nuclei (long arrow). Transmission electron micrograph, x 75000.
basal lamina (Fig. 4a). Some of the pericytes had a bossed surface. The reticulin fibres arranged in between showed focal areas with a club-like surface and marked network-like branching. They enclosed individual tumor cells or small tumor cell groups, and in between were capillaries filled with erythrocytes (Fig. 4b). Discussion
The differential diagnosis between benign and malignant hemangiopericytomas is often considered difficult. Malignant hemangiopericytomas can be diagnosed with great accuracy by application of the criteria of ENZINGER & SMITH (4). The classification of heman-
giopericytomas exhibiting a histologically and cytologically benign picture, however, can be difficult. These tumors can recur years or decades later - latency periods up to 33 years have been reported (8). Late metastases have also been reported. SHIN et al. (9) presented a patient in whom a metastasis occurred 28 years after initial diagnosis. Patient 3 presents a similar pattern, in that the tumor appeared to be benign both histo- and cytologically, but caused the patient's death 16 years after the first operation from ensuing lung and liver metastases. Inspite of light, scanning and transmission electron microscopy as well as immunohistochemical and electron microscopical studies no definite histological criteria indicative of the
biological pattern of so-called "benign" hemangiopericytomas could be established. The occurrence of metastases even after many years makes the existence of benign hemangiopericytomas questionable. It appears appropriate to consider all hemangiopericytomas as potentially malignant. The clinical course alone determines whether or not the tumor should be called benign or malignant. An observation period of at least 10 years is required before a fairly reliable statement can be made about the behavior of the tumor. Trauma has also been discussed as a cause of hemangiopericytomas (5). In 2 of our cases trauma was mentioned in the history. The treatment of choice is complete
102
Philippou and Gellrich
Fig. 4a. Below the basal lamina (white arrows) of the endothelial cells reticulin fibres surrounding tumor cells with intact cytoplasmic extensions (black arrows) reaching the basal lamina. Scanning electron micrograph, x 2932. Fig. 4b. Root-like branched reticulin fibres (long arrow) with tumor cells lying in between and capillary vessels filled with erythrocytes (short arrow). Scanning electron micrograph, x 2000.
Fig. 5a. Preoperative angiography of the infratemporal tumor vascular bed subsequent to embolisation with Terbal particles and platinum minispirals (arrow). Fig. 5b. Contrast medium (Gadolinium) - enhanced magnetic resonance tomograph in AP projection with distinctly depicted tumor (arrow) involving the cranial base.
surgical excision. Radical removal of the tumor at the cranial bone is not always possible. Preoperative angiography with simultaneous embolisation via micro particles (e.g. Terbal 10-140/~) or platinum minispirals (Fig. 5a) may be helpful in reducing the size of the tumor before surgery, as well as the risk of intraoperative hemorrhage. The chance of intraoperative distribution of tumor cells is also diminished. Postoperative radiotherapy is recommended at least in cases of incomplete tumor removal, although these tumors are considered to be fairly resistant to radiotherapy (2). In the cases presented the primary tumor or the recurrence was treated with
50-60 Gy. Nevertheless, the tumor metastasized in 2 of the patients after 11 and 7 years. If surgical and radiotherapeutic means are exhausted, chemotherapy may be considered. Positive results are reported only for adriamycin alone or in combination with cyclophosphamid, vincristin, DTIC, methotrexat or actinomycin D (3, 7, 11). Some authors consider hemangiopericytomas to be chemotherapy-resistant (1, 6, 10). Lifelong follow-up of patients with hemangiopericytomas is mandatory. Magnetic resonance tomography is the preferred diagnostic aid since this is the most sensitive procedure for demonstrating mesenchymal neoplasms (Fig.
5b). Computerized tomography should be used if bone involvement is to be ruled out. No antibodies specific to hemangiopericytoma are available. In all 3 cases examined the VIM-reaction was positive, showing the mesenchymal character of this tumor. The ATT and ATCT reaction was positive in only a few tumor cells. This reaction is probably indicative of a phagocytic potential of the pericytes. The negative DES reaction in all cases examined could possibly be due to fixation of the material. The immunoelectron microscopic demonstration of ACT in individual tumor cells in the vicinity of the intracytoplasmic microfilamentary structures, which are also positive for VIM in immunoelectron microscopy, is probably based on the contractile character of the cell of origin. The histological studies can be significantly complemented by scanning and transmission electron microscopy, as well as immunohistochemistry and electron microscopy. None of the methods used, however, is reliable enough to state with certainty whether the tumor is benign or malignant.
References 1. ATKINSDN JB, MAHOURGH, ISAACSH,
ORTEGAJA. Hemangiopericytoma in infants and children. Am J Surg 1984: 148: 372-4. 2. BACKWINKELK, DIDDAMMSJA. Heman-
giopericytoma. Report of a case and comprehensive review of the literature. Cancer 1970: 25: 896-901. 3. BEADLEGF, HILLCOATBL. Treatment of
Hemangiopericytoma advanced malignant hemangiopericytoma with combination adriamycin and DTIC: a report of four cases. J Surg Oncol 1983: 22: 167-70. 4. ENZINGERFM, SMITHBH. Hemangiopericytoma. An analysis of 106 cases. Hum Pathol 1976: 7: 61-82. 5. GHUSSENF, NAGELK. Klinik und Therapie des H/imangiopericytoms. Schweiz Med Wochenschr 1981: 111:385 8. 6. McMASTER MJ, SOULEEH, IvIYs JC. Hemangiopericytoma. Long-term followup of 60 patients. Cancer 1975: 36: 2232~44. 7. NATHANSON DS. Preoperative chemo-
therapy and irradiation in the treatment of soft tissue sarcomas of the lower extremities: preliminary report of experience at Henry Ford Hospital. Henry Ford Hosp Med J 1984: 32" 31-8. 8. RICE CD, KERSTEN RC, MRAK RE. An orbital hemangiopericytoma recurrent after 33 years. Arch Ophthalmol 1989: 107: 552-6. 9. SHIN MS, KOEHLER RE, STANLEY R J, BARTONJC, HO K-J. Malignant hemangiopericytoma: computed tomography and magnetic resonance imaging. J Comput Tomogr 1987: 11:297 300.
103
10. WEBERBP, SCHRADERM, INNIGERR. Maligne H~mangiopericytome in KopfHals-Bereich. HNO 1990: 38: 326-33. 11. WONG PP, YAGODAA. Chemotherapy of malignant hemangiopericytoma. Cancer 1978: 41: 1256-60. Address:
Dr. S. Philippou Department of Pathology Ruhr University Bochum Universitgitsstrafle 150 4630 Bochum 1 Germany
