540
6 1990 The Japanese Society
of Pathology
Giant Cell Fibroblastoma A Case Report
Takanori Hirose’, Masamichi Sasaki2, Masayuki Shintaku2, Tadashi Hasegawa’, Eiji Kudo’, Toshiaki Sano’, and Kazuo Hizawa]
A case of giant cell fibroblastoma occurring in the knee of a 16-month-old girl is reported. The ill-defined subcutaneous tumor measuring 2 x 2 cm was composed of diffusely proliferating spindle-shaped tumor cells with scattered, atypical multinucleated giant cells in a myxoid or collagenous background and irregularly branching sinusoidlike tissue spaces. In addition to floret-type giant cells, a few osteoclast-like giant cells were present in a cellular area where tumor cells were focally arranged in a storiform pattern. lmmunohistochemically, the tumor cells gave positive reactions for only vimentin and actin. I n spite of the high recurrence rate of this type of tumor, the course of the patient after excision of the tumor has been uneventful. It is important to distinguish this rare, peculiar fibrous tumor from other soft tissue tumors including some sarcomas. Acta Pathol Jpn 40: 540-544, 1990. Key words : Giant cell, Fibroblastoma, Immunohistochemis-
try
INTRODUCTION A number of soft tissue tumors are known to occur exclusively or preferentially in children. In particular, some fibrous tumors develop only in children, and Enzinger and Weiss (1) devoted a chapter of their textbook to “Fibrous proliferations of infancy and childhood“. In 1982, Shmookler and Enzinger (2) first reported a peculiar fibrous tumor of infancy and childhood named “giant cell fibroblastoma”. This tumor is characterized by proliferation of spindle-shaped tumor cells including Received January 31, 1990. Accepted for publication April 16, 1990. ‘First Department of Pathology, University of Tokushima School of Medicine, Tokushima. 2Department of Pathology, Osaka Red Cross Hospital, Osaka. Mailing address: Takanori Hirose, M.D. (LBRRIJ),First Department of Pathology, University of Tokushima School of Medicine, Kuramoto-cho 3-18-15, Tokushima 770, Japan.
multinucleated giant cells and sinusoid-like tissue spaces, and has a high recurrence rate. Since its first description, 48 cases have been reported (3-9). Here, we report a case of giant cell fibroblastoma, which is, to our knowledge, the first in Japan, and a description of its immuno histoc hemica I features.
CLINICAL SUMMARY A 16-month-old girl was noted by her parents to have a small asymptomatic mass on the medial portion of her left knee in May, 1984. As this mass gradually increased in size, it was excised in January, 1985. The resected tumor, which measured 2x2 cm, involved the subcutaneous tissue without adhering to surrounding tissue. Its cut surface was solid and somewhat myxoid, with no area of necrosis or hemorrhage. The patient received no further treatment, and has been doing well with no evidence of recurrence or metastasis for 5 years since the operation.
PATHOLOGICAL FINDINGS Histological examination showed that the tumor consisted of spindle-shaped cells with scattered atypical giant cells proliferating in a myxoid or collagenous background (Fig. 1). In myxoid areas, the short spindleshaped tumor cells of uniform shape had ovoid, vesicular nuclei and scant cytoplasm (Fig. 2a). In collagenous areas, mainly located in peripheral portions of the tumor, wavy, spindle-shaped tumor cells with pyknotic nuclei and slender cytoplasmic extensions proliferated in parallel with collagen fibers (Fig. 2b). Among these myxoid and collagenous areas, there was also a small area in which plump spindle-shaped cells were arranged in a storiform pattern (Fig. 3). A few mitoses were seen in this cellular area, but scarcely any in other areas.
541
Acta Pathologica Japonica 40 (7): 1990
Figure 1. Micrograph of the present giant cell fibroblastoma. Spindle-shaped tumor cells proliferate in myxoid and collagenous areas. Note a few atypical giant cells and entrapped sweat glands (HE stain).
A t y pica I mu1t inucleated giant cells, characteristic const ituents of this tumor, were intermingled with spindleshaped tumor cells and tended to lie in groups. The cellular area contained numerous floret-type giant cells characterized by multiple peripherally placed nuclei and abundant central cytoplasm (Fig. 4a), and a few osteoclast-like giant cells with some ovoid, centrally located nuclei (Fig. 4b). In addition, bizarre, spindle-shaped giant cells with pyknotic, overlapping or multilobated nuclei were scattered in the collagenous areas (Figs. 1,
5). Many small vacuolar spaces were seen around these giant cells (Fig. 4a). These pericellular spaces were connected to each other and seemed to form numerous irregular slit-like clefts or sinusoid-like spaces in the collagenous areas (Fig. 5). These characteristic spaces were rimmed by spindle-shaped mononucleated cells and collagen fibers in addition to giant cells, but not by endothelial cells. Numerous, large and small blood vessels were present throughout the tumor and showed no continuity with the sinusoid-like spaces. The tumor
Figure 2. (a) A myxoid area containing evenly distributed, short-spindle tumor cells. Tumor cells have an ovoid, vesicular nucleus and scant cytoplasm (HE stain). (b) A collagenous area of the giant cell fibroblastoma. Wavy spindle-shaped cells proliferate in parallel with collagen fibers (HE stain).
542
Giant Cell Fibroblastoma (Hirose et a/.)
Figure 3. A cellular area, focally showing a storiforrn pattern (HE stain).
infiltrated into the surrounding tissue, entrapping residual adipose tissue, sweat glands and peripheral nerves (Fig. 1). A few mast cells and small lymphocytes were present, but foamy cells or hemosiderin granules were not seen in the tumor. lmmunohistochemical staining was performed on paraffin sections of formalin-fixed tissues. Positive reactions with monoclonal anti-vimentin antibody (1 : 10, DAKO) and monoclonal anti-alpha-smooth muscle actin antibody (1 : 1,000, Biomakor) were demonstrated by the avidin-biotin-peroxidase complex (ABC) method using an ABC kit (Vector Lab.). Most spindle-shaped tumor cells and a few multinucleated giant cells were vimentin positive, whereas only some spindle-shaped cells, in addition to smooth muscle cells of blood vessels, in the cellular area were weakly positive for actin (Fig. 6). No spindle-shaped tumor cells or giant cells showed immunoreactivity for S-100 protein, Leu--7, epithelial membrane antigen, desmin, myoglobin, alpha-1 -antichymotrypsin or factor VIII-related antigen. The tumor cells also did not react with Ulex europaeus I lectin.
Figure 4. (a) Floret-type giant cells with multiple peripherally located nuclei and central cytoplasm. Note vacuolar spaces around the giant cells (HE stain). (b) Osteoclast-like giant cells containing some central nuclei in amphophilic cytoplasm (HE stain).
Table 1. Summary of 49 Cases of Giant Cell Fibroblastoma Patient age Sex Tumor location
Tumor size Recurrence Metastasis
4 months-64 years (mean 9.2 years) male (32), female (17) trunk (23) chest wall (6),inguinal region (5),back (4), abdominal wall (31, perineum and scrotum (3),clavicular region (2) lower extremities (11) thigh-knee (7), foot (2). lower leg (l), buttock (1) upper extremities (10) shoulder-axilla (7), hand (3) neck (5) 0.8-8 c m (mean 3.7 cm) 16/32 none
Acta Pathologica Japonica 40 (7): 1990
543
Figure 5. Sinusoid-like tissue clefts, rimmed by atypical spindle-shaped giant cells, small tumor cells and collagen (HE stain).
Figure 6. lmmunoreactivity with antialpha-smooth muscle actin antibody. Some spindle-shaped tumor cells and smooth muscle cells of blood vessels in a cellular area are actin-positive (ABC method).
DISCUSSION Forty-eight cases of giant cell fibroblastoma have been reported (3-9). The present case showed the characteristic clinicopathological features of this type of tumor (Tablel). The patients reported ranged in age from 4 months to 64 years, but three-quarters of them (36 cases) were under 10 years old, indicating the predominant occurrence of this tumor in infancy and childhood. Two thirds of the cases were in males. Of the tumors, 2 3 (47%) were in the trunk, 11 (22%) in the lower extremities, 10 (20%) in the upper extremities and 5 (10%) in the neck. The tumor generally appeared as an asymptomatic, subcutaneous or dermal mass, measuring 0.8 to 8 c m in diameter at the time of surgery. In half the patients the tumor recurred locally, but
no metastases have been reported. The characteristic microscopic features of this tumor, described in most reports (2-10), are the presence of scattered multinucleated giant cells and irregular sinusoidal or angiectoid areas. These pseudovascular regions vary in both size and proportion in different cases (5, 9). Some tumors (5, 6) have been reported to contain cavernous hemangioma-like spaces, whereas others (5, 7) have only slit-like spaces, as in the present case. These sinusoid-like spaces, often lined by multinucleated giant cells instead of endothelial cells, are frequently associated with stromal hyalinization (6, 9). In addition, in the present case, numerous small vacuolar spaces were seen around giant cells. Although there has been no convincing theory of how the sinusoid-like spaces are formed, stromal hyalinization may cause progressive
544
Giant Cell Fibroblastoma (Hirose e t a / . )
dilatation of pericellular spaces and clefts (9). In addition to the floret-type giant cells described in many reports (5, 6, lo), a few osteoclast-like giant cells, which have not been described previously, were present in the cellular area in the present case. Studies on further cases will be necessary in order to clarify whether osteoclast-like giant cells are common or rare to this type of tumor. The exact nature of giant cell fibroblastoma is unknown. Barr et a/. (4) suggested fibrohistiocytic differentiation based on a positive reaction for alpha-l-antichymotrypsin in one tumor. However, no positive reaction was observed in other tumors(6-8) including the present case. An endothelial nature of the tumor cells is excluded by the absence of both factor VIII-related antigen and reactivity with Ulex europaeus I lectin (3-8). Fletcher (6) suggested the possibility of perineurial fibroblastic differentiation. However, epithelial membrane antigen, recently found to be a perineurial cell marker (11, 12), was not be detected in the present case. Dymock et a/. (5) and Chou et a/. (8) stated that giant cell fibroblastoma should be classified as fibromatosis of infancy and childhood. Although fibromatosis is an infiltrating fibroblastic tumor with a high recurrence rate, it differs from giant cell fibroblastoma in that it is located in deep muscular tissue and shows more aggressive behavior. Shmookler et a/. (9) regarded giant cell fibroblastoma as a juvenile form of dermatofibrosarcoma protuberans (DFSP) and pointed out some clinical and morphologic similarities between the two. As described by them(9), the present tumor contained a small area showing a storiform pattern. However, DFSP and giant cell fibroblastoma exhibit different immunoreactions with anti-actin antibodies. The two giant cell fibroblastomas reported by Chou et a/. (8), and the present case, were actin-positive, suggesting myofibroblastic differentiation of some tumor cells (13), whereas DFSP has been reported to be actin-negative (14). In the immunohistochemical studies on giant cell fibroblastomas reported so for, only the reaction for vimentin has constantly been positive (6-8). Therefore, giant cell fibroblastoma seems to be a fibroblastic or primitive mesenchymal cell tumor, which is also suggested by ultrastructural studies (2-3, 5, 7-9). The recognition of giant cell fibroblastoma is important to avoid its misdiagnosis, particularly as a malignant tumor. Some reported cases have been identified as malignant tumors, such as liposarcoma, myxoid
malignant fibrous hist iocytoma, ang iosarcoma or ma lignant schwannoma, because of their complex microscopic features and the presence of atypical giant cells (3, 6, 810). Once its distinctive morphological features are known, giant cell fibroblastoma seems easy to recognize. In spite of its high recurrence rate, this tumor is curable by adequate excision.
REFERENCES 1. Enzinger FM and Weiss SW. Soft tissue tumors, 2nd ed. Mosby, St. Louis, 1988. 2. Shmookler BM and Enzinger FM. Giant cell fibroblastoma. A peculiar childhood tumor. Lab Invest 46: 76A, 1982. 3. Abdul-Karim FW, Evans HL, and Silva EG. Giant cell fibroblastoma. A report of three cases. Am J Clin Pathol 83: 165-170, 1985. 4. Barr RJ, Young EM, and Liao S-Y. Giant cell fibroblastoma. An immunohistochemical study. J Cutan Pathol 13: 301-307, 1986. 5. Dymock RB, Allen PW, Stirling JW, et a/. Giant cell fibroblastoma. A distinctive, recurrent tumor of childhood. Am J Surg Pathol 11 : 263-271, 1987. 6. Fletcher CDM. Giant cell fibroblastoma of soft tissue. A clinicopathological and immunohistochemical study. Histopathology 13 : 499-508, 1988. 7. Rosen LB, Amazon K, Weitzner J, et a/. Giant cell fibro-blastoma. A report of a case and review of the literature. Am J Dermatopathol 11 : 242-247, 1989. 8. Chou P, Gonzalez-Crussi F, and Mangkornkanok M. Giant cell fibroblastoma. Cancer 63 : 756-762, 1989. 9. Shmookler BM, Enzinger FM, and Weiss SW. Giant cell fibroblastoma. A juvenile form of dermatofibrosarcoma protuberans. Cancer 6 4 : 2154-2161, 1989. 10. Chung EB. Pitfalls in diagnosing benign soft tissue tumors in infancy and childhood. Pathol Annu 20: 323-386, 1985. 11. Perentes E, Nakagawa Y, Ross GW, et a/. Expression of epithelial membrane antigen in perineurial cells and their derivatives. An immunohistochemical study with multiple markers. Acta Neuropathol (Berl) 7 5 : 160165, 1987. 12. Hirose T, Sumitomo M, Kudo E, et a/. Malignant peripheral nerve sheath tumor (MPNST) showing perineurial cell differentiation. Am J Surg Pathol 13: 613-620, 1989. 13. Hasegawa T, Hirose T, Kudo E, et a/. Cytoskeletal characteristics of myofibroblasts in benign neoplastic and reactive fibroblastic lesions. Virchows Arch [A] 416: 375-382, 1990. 14. Miettinen M. Antibody specific to muscle actins in the diagnosis and classification of soft tissue tumors. Am J Pathol 130 : 205-21 5, 1988.
6 1990 The Japanese Society
of Pathology
Giant Cell Fibroblastoma A Case Report
Takanori Hirose’, Masamichi Sasaki2, Masayuki Shintaku2, Tadashi Hasegawa’, Eiji Kudo’, Toshiaki Sano’, and Kazuo Hizawa]
A case of giant cell fibroblastoma occurring in the knee of a 16-month-old girl is reported. The ill-defined subcutaneous tumor measuring 2 x 2 cm was composed of diffusely proliferating spindle-shaped tumor cells with scattered, atypical multinucleated giant cells in a myxoid or collagenous background and irregularly branching sinusoidlike tissue spaces. In addition to floret-type giant cells, a few osteoclast-like giant cells were present in a cellular area where tumor cells were focally arranged in a storiform pattern. lmmunohistochemically, the tumor cells gave positive reactions for only vimentin and actin. I n spite of the high recurrence rate of this type of tumor, the course of the patient after excision of the tumor has been uneventful. It is important to distinguish this rare, peculiar fibrous tumor from other soft tissue tumors including some sarcomas. Acta Pathol Jpn 40: 540-544, 1990. Key words : Giant cell, Fibroblastoma, Immunohistochemis-
try
INTRODUCTION A number of soft tissue tumors are known to occur exclusively or preferentially in children. In particular, some fibrous tumors develop only in children, and Enzinger and Weiss (1) devoted a chapter of their textbook to “Fibrous proliferations of infancy and childhood“. In 1982, Shmookler and Enzinger (2) first reported a peculiar fibrous tumor of infancy and childhood named “giant cell fibroblastoma”. This tumor is characterized by proliferation of spindle-shaped tumor cells including Received January 31, 1990. Accepted for publication April 16, 1990. ‘First Department of Pathology, University of Tokushima School of Medicine, Tokushima. 2Department of Pathology, Osaka Red Cross Hospital, Osaka. Mailing address: Takanori Hirose, M.D. (LBRRIJ),First Department of Pathology, University of Tokushima School of Medicine, Kuramoto-cho 3-18-15, Tokushima 770, Japan.
multinucleated giant cells and sinusoid-like tissue spaces, and has a high recurrence rate. Since its first description, 48 cases have been reported (3-9). Here, we report a case of giant cell fibroblastoma, which is, to our knowledge, the first in Japan, and a description of its immuno histoc hemica I features.
CLINICAL SUMMARY A 16-month-old girl was noted by her parents to have a small asymptomatic mass on the medial portion of her left knee in May, 1984. As this mass gradually increased in size, it was excised in January, 1985. The resected tumor, which measured 2x2 cm, involved the subcutaneous tissue without adhering to surrounding tissue. Its cut surface was solid and somewhat myxoid, with no area of necrosis or hemorrhage. The patient received no further treatment, and has been doing well with no evidence of recurrence or metastasis for 5 years since the operation.
PATHOLOGICAL FINDINGS Histological examination showed that the tumor consisted of spindle-shaped cells with scattered atypical giant cells proliferating in a myxoid or collagenous background (Fig. 1). In myxoid areas, the short spindleshaped tumor cells of uniform shape had ovoid, vesicular nuclei and scant cytoplasm (Fig. 2a). In collagenous areas, mainly located in peripheral portions of the tumor, wavy, spindle-shaped tumor cells with pyknotic nuclei and slender cytoplasmic extensions proliferated in parallel with collagen fibers (Fig. 2b). Among these myxoid and collagenous areas, there was also a small area in which plump spindle-shaped cells were arranged in a storiform pattern (Fig. 3). A few mitoses were seen in this cellular area, but scarcely any in other areas.
541
Acta Pathologica Japonica 40 (7): 1990
Figure 1. Micrograph of the present giant cell fibroblastoma. Spindle-shaped tumor cells proliferate in myxoid and collagenous areas. Note a few atypical giant cells and entrapped sweat glands (HE stain).
A t y pica I mu1t inucleated giant cells, characteristic const ituents of this tumor, were intermingled with spindleshaped tumor cells and tended to lie in groups. The cellular area contained numerous floret-type giant cells characterized by multiple peripherally placed nuclei and abundant central cytoplasm (Fig. 4a), and a few osteoclast-like giant cells with some ovoid, centrally located nuclei (Fig. 4b). In addition, bizarre, spindle-shaped giant cells with pyknotic, overlapping or multilobated nuclei were scattered in the collagenous areas (Figs. 1,
5). Many small vacuolar spaces were seen around these giant cells (Fig. 4a). These pericellular spaces were connected to each other and seemed to form numerous irregular slit-like clefts or sinusoid-like spaces in the collagenous areas (Fig. 5). These characteristic spaces were rimmed by spindle-shaped mononucleated cells and collagen fibers in addition to giant cells, but not by endothelial cells. Numerous, large and small blood vessels were present throughout the tumor and showed no continuity with the sinusoid-like spaces. The tumor
Figure 2. (a) A myxoid area containing evenly distributed, short-spindle tumor cells. Tumor cells have an ovoid, vesicular nucleus and scant cytoplasm (HE stain). (b) A collagenous area of the giant cell fibroblastoma. Wavy spindle-shaped cells proliferate in parallel with collagen fibers (HE stain).
542
Giant Cell Fibroblastoma (Hirose et a/.)
Figure 3. A cellular area, focally showing a storiforrn pattern (HE stain).
infiltrated into the surrounding tissue, entrapping residual adipose tissue, sweat glands and peripheral nerves (Fig. 1). A few mast cells and small lymphocytes were present, but foamy cells or hemosiderin granules were not seen in the tumor. lmmunohistochemical staining was performed on paraffin sections of formalin-fixed tissues. Positive reactions with monoclonal anti-vimentin antibody (1 : 10, DAKO) and monoclonal anti-alpha-smooth muscle actin antibody (1 : 1,000, Biomakor) were demonstrated by the avidin-biotin-peroxidase complex (ABC) method using an ABC kit (Vector Lab.). Most spindle-shaped tumor cells and a few multinucleated giant cells were vimentin positive, whereas only some spindle-shaped cells, in addition to smooth muscle cells of blood vessels, in the cellular area were weakly positive for actin (Fig. 6). No spindle-shaped tumor cells or giant cells showed immunoreactivity for S-100 protein, Leu--7, epithelial membrane antigen, desmin, myoglobin, alpha-1 -antichymotrypsin or factor VIII-related antigen. The tumor cells also did not react with Ulex europaeus I lectin.
Figure 4. (a) Floret-type giant cells with multiple peripherally located nuclei and central cytoplasm. Note vacuolar spaces around the giant cells (HE stain). (b) Osteoclast-like giant cells containing some central nuclei in amphophilic cytoplasm (HE stain).
Table 1. Summary of 49 Cases of Giant Cell Fibroblastoma Patient age Sex Tumor location
Tumor size Recurrence Metastasis
4 months-64 years (mean 9.2 years) male (32), female (17) trunk (23) chest wall (6),inguinal region (5),back (4), abdominal wall (31, perineum and scrotum (3),clavicular region (2) lower extremities (11) thigh-knee (7), foot (2). lower leg (l), buttock (1) upper extremities (10) shoulder-axilla (7), hand (3) neck (5) 0.8-8 c m (mean 3.7 cm) 16/32 none
Acta Pathologica Japonica 40 (7): 1990
543
Figure 5. Sinusoid-like tissue clefts, rimmed by atypical spindle-shaped giant cells, small tumor cells and collagen (HE stain).
Figure 6. lmmunoreactivity with antialpha-smooth muscle actin antibody. Some spindle-shaped tumor cells and smooth muscle cells of blood vessels in a cellular area are actin-positive (ABC method).
DISCUSSION Forty-eight cases of giant cell fibroblastoma have been reported (3-9). The present case showed the characteristic clinicopathological features of this type of tumor (Tablel). The patients reported ranged in age from 4 months to 64 years, but three-quarters of them (36 cases) were under 10 years old, indicating the predominant occurrence of this tumor in infancy and childhood. Two thirds of the cases were in males. Of the tumors, 2 3 (47%) were in the trunk, 11 (22%) in the lower extremities, 10 (20%) in the upper extremities and 5 (10%) in the neck. The tumor generally appeared as an asymptomatic, subcutaneous or dermal mass, measuring 0.8 to 8 c m in diameter at the time of surgery. In half the patients the tumor recurred locally, but
no metastases have been reported. The characteristic microscopic features of this tumor, described in most reports (2-10), are the presence of scattered multinucleated giant cells and irregular sinusoidal or angiectoid areas. These pseudovascular regions vary in both size and proportion in different cases (5, 9). Some tumors (5, 6) have been reported to contain cavernous hemangioma-like spaces, whereas others (5, 7) have only slit-like spaces, as in the present case. These sinusoid-like spaces, often lined by multinucleated giant cells instead of endothelial cells, are frequently associated with stromal hyalinization (6, 9). In addition, in the present case, numerous small vacuolar spaces were seen around giant cells. Although there has been no convincing theory of how the sinusoid-like spaces are formed, stromal hyalinization may cause progressive
544
Giant Cell Fibroblastoma (Hirose e t a / . )
dilatation of pericellular spaces and clefts (9). In addition to the floret-type giant cells described in many reports (5, 6, lo), a few osteoclast-like giant cells, which have not been described previously, were present in the cellular area in the present case. Studies on further cases will be necessary in order to clarify whether osteoclast-like giant cells are common or rare to this type of tumor. The exact nature of giant cell fibroblastoma is unknown. Barr et a/. (4) suggested fibrohistiocytic differentiation based on a positive reaction for alpha-l-antichymotrypsin in one tumor. However, no positive reaction was observed in other tumors(6-8) including the present case. An endothelial nature of the tumor cells is excluded by the absence of both factor VIII-related antigen and reactivity with Ulex europaeus I lectin (3-8). Fletcher (6) suggested the possibility of perineurial fibroblastic differentiation. However, epithelial membrane antigen, recently found to be a perineurial cell marker (11, 12), was not be detected in the present case. Dymock et a/. (5) and Chou et a/. (8) stated that giant cell fibroblastoma should be classified as fibromatosis of infancy and childhood. Although fibromatosis is an infiltrating fibroblastic tumor with a high recurrence rate, it differs from giant cell fibroblastoma in that it is located in deep muscular tissue and shows more aggressive behavior. Shmookler et a/. (9) regarded giant cell fibroblastoma as a juvenile form of dermatofibrosarcoma protuberans (DFSP) and pointed out some clinical and morphologic similarities between the two. As described by them(9), the present tumor contained a small area showing a storiform pattern. However, DFSP and giant cell fibroblastoma exhibit different immunoreactions with anti-actin antibodies. The two giant cell fibroblastomas reported by Chou et a/. (8), and the present case, were actin-positive, suggesting myofibroblastic differentiation of some tumor cells (13), whereas DFSP has been reported to be actin-negative (14). In the immunohistochemical studies on giant cell fibroblastomas reported so for, only the reaction for vimentin has constantly been positive (6-8). Therefore, giant cell fibroblastoma seems to be a fibroblastic or primitive mesenchymal cell tumor, which is also suggested by ultrastructural studies (2-3, 5, 7-9). The recognition of giant cell fibroblastoma is important to avoid its misdiagnosis, particularly as a malignant tumor. Some reported cases have been identified as malignant tumors, such as liposarcoma, myxoid
malignant fibrous hist iocytoma, ang iosarcoma or ma lignant schwannoma, because of their complex microscopic features and the presence of atypical giant cells (3, 6, 810). Once its distinctive morphological features are known, giant cell fibroblastoma seems easy to recognize. In spite of its high recurrence rate, this tumor is curable by adequate excision.
REFERENCES 1. Enzinger FM and Weiss SW. Soft tissue tumors, 2nd ed. Mosby, St. Louis, 1988. 2. Shmookler BM and Enzinger FM. Giant cell fibroblastoma. A peculiar childhood tumor. Lab Invest 46: 76A, 1982. 3. Abdul-Karim FW, Evans HL, and Silva EG. Giant cell fibroblastoma. A report of three cases. Am J Clin Pathol 83: 165-170, 1985. 4. Barr RJ, Young EM, and Liao S-Y. Giant cell fibroblastoma. An immunohistochemical study. J Cutan Pathol 13: 301-307, 1986. 5. Dymock RB, Allen PW, Stirling JW, et a/. Giant cell fibroblastoma. A distinctive, recurrent tumor of childhood. Am J Surg Pathol 11 : 263-271, 1987. 6. Fletcher CDM. Giant cell fibroblastoma of soft tissue. A clinicopathological and immunohistochemical study. Histopathology 13 : 499-508, 1988. 7. Rosen LB, Amazon K, Weitzner J, et a/. Giant cell fibro-blastoma. A report of a case and review of the literature. Am J Dermatopathol 11 : 242-247, 1989. 8. Chou P, Gonzalez-Crussi F, and Mangkornkanok M. Giant cell fibroblastoma. Cancer 63 : 756-762, 1989. 9. Shmookler BM, Enzinger FM, and Weiss SW. Giant cell fibroblastoma. A juvenile form of dermatofibrosarcoma protuberans. Cancer 6 4 : 2154-2161, 1989. 10. Chung EB. Pitfalls in diagnosing benign soft tissue tumors in infancy and childhood. Pathol Annu 20: 323-386, 1985. 11. Perentes E, Nakagawa Y, Ross GW, et a/. Expression of epithelial membrane antigen in perineurial cells and their derivatives. An immunohistochemical study with multiple markers. Acta Neuropathol (Berl) 7 5 : 160165, 1987. 12. Hirose T, Sumitomo M, Kudo E, et a/. Malignant peripheral nerve sheath tumor (MPNST) showing perineurial cell differentiation. Am J Surg Pathol 13: 613-620, 1989. 13. Hasegawa T, Hirose T, Kudo E, et a/. Cytoskeletal characteristics of myofibroblasts in benign neoplastic and reactive fibroblastic lesions. Virchows Arch [A] 416: 375-382, 1990. 14. Miettinen M. Antibody specific to muscle actins in the diagnosis and classification of soft tissue tumors. Am J Pathol 130 : 205-21 5, 1988.
