Abstract
Hemangiopericytoma/solitary fibrous tumor is a very rare tumor of uncertain malignant potential. About 300 such cases have been reported since 1942, when Stout and Murray described these tumors as “vascular tumors arising from Zimmerman's pericytes”. Under the World Health Organization (WHO) classification, hemangiopericytomas and solitary fibrous tumors of the soft tissues are regarded as features of the same entity in the soft tissue fascicle. We report the case of a 54-year-old woman who presented with a painless right-side cheek mass of 2 cm maximum diameter. The lesion was completely removed by wide surgical resection. Histologically, the tumour had staghorn-like vasculature and immunohistochemistry for Calponin, CD68 KP1, AE1-AE3, smooth muscle actin and P63, S-100 was negative; that for CD34 was positive. A diagnosis of hemangiopericytoma/solitary fibrous tumor was rendered. The patient had a normal postoperative course of healing, and 24 months later remains asymptomatic, without signs of recurrence or metastasis. Because of the rarity and unpredictable biological behavior of these tumors, long-term follow-up is necessary even after radical resection because recurrence or development of metastasis may be delayed by many years.
The term hemangiopericytoma (HPC) was introduced by Stout and Murray in 1942 for tumors located in the retroperitoneum, buttock, and thigh (1). They proposed an origin from pericytic-modified smooth muscle cells located around the blood vessels, a cell-type described by Zimmermann in 1923 (2).
The solitary fibrous tumor (SFT) was first described in the pleura, by Klemperer and Rabin in 1931 (3), and was regarded originally as mesothelioma (4). Subsequently, SFTs have been observed at a number of extrapleural sites (5-7), including the soft tissues (8).
In the 2006 World Health Organization (WHO) fascicle of soft tissue tumors, it is stated that the histological appearance and clinical behavior of HPC and solitary fibrous tumor are similar, a view widely shared (8, 9). Accordingly, the unifying term ‘hemangiopericytoma/solitary fibrous tumor’ (HPC/SFT) has been proposed (10).
HPC/SFT have been reported at various head and neck sites, including the meninges (11), thyroid (12, 13), larynx (14, 15), nasal cavity (16), paranasal sinuses (17), orbit (18), nasopharynx (19), salivary glands, submandibular gland (20-22), sublingual gland (20, 23, 24), parotid gland (20, 25) and in the oral cavity (26, 27). There are also reports of six cases of SFT of which the exact site of origin remains unclear (20, 25, 26). We describe a case of SFT involving the cheek, of which to our knowledge, very few have been reported.
HPC/SFT located at the oral cavity occurs most often in adults (mean age=52 years), with a slight female predilection. The patients commonly complain of a slowly growing, well-circumscribed, asymptomatic mass. However, other symptoms include pain (20, 25, 28), dysphagia, obstructive sleep apnea, and altered speech (29). Systemic signs and paraneoplastic syndromes have not been reported, although these features have been described in a case of intrathoracic location (30).
Here we report a case of HPC/SFT and illustrate the morphological, immunohistochemical and clinical aspects of this very rare tumor of the oral cavity.
Case Report
A 54-year-old woman presented to our Department of Oral Pathology with a painless right-side cheek mass of 2 cm in maximum diameter. The mass was well circumscribed, mobile and soft at palpation. The overlying mucosa was intact and normal. The lesion was completely removed by wide surgical resection. The histological diagnosis was of SFT, cellular variant, with hemangiopericytoma-like features. The patient had a normal postoperative course of healing, and 24 months later remains asymptomatic, without signs of recurrence or metastasis.
Islands of cells arranged in multilobular aspect separated by collagen fibers (H&E, original magnification ×100).
Histopathological examination revealed a cellular, highly vascularized tumor, with staghorn vasculature, collagen bundles, and rare mitoses. Cellularity was moderate to high (Figures 1 and 2). Immunohistochemistry was carried out for calponin, CD34, CD68KP1, CD31, AE1-AE3, smooth muscle actin (SMA), P63 and S-100: The list of primary antibodies with their respective dilutions is given in Table I. A standard procedure with antibodies and the avidin/biotin method was used. The spindled tumor cells were negative for the following markers: calponin, CD68KP1, AE1-AE3, SMA P63 and S-100; CD34 staining was strongly positive (Figure 3), the immunohistochemical profile was consistent with a diagnosis of HPC/SFT.
Discussion
The histopathological diagnosis of these vascularized tumors is challenging, in particular because of the difficulty in differentiating HPC from other tumors types that have prominent vascularization: schwannoma, myofibroblastoma, metastasis from spindle-cell carcinoma, low-grade fibromyxoid sarcoma (especially if myxoid foci are prominent), synovial sarcoma, and malignant peripheral nerve sheath tumor (1). Angiographic features frequently help to differentiate HPC from other hypervascular lesions.
List of antibodies used and results (Dako, Denmark).
From the morphological standpoint, they generally have a monotonous appearance, with moderate-to-high cellularity, little fibrosis, numerous thin-walled ‘staghorn’ branching vessels, and round-to-oval monomorphic tumor cell nuclei (31). Immunohistochemically, the neoplastic cells do not stain for epithelial, melanocytic, or neural markers. Immunohistochemistry showed reactivity for CD34 and BCL-2 in many cases. These tumor cells are also positive for vimentin and SMA stains (32). In our case, immunohistochemistry demonstrated no expression of calponin, CD68KP1, AE1-AE3, SMA, P63 and S-100, but positive expression for CD34, occurring both in spindle cells and vessel walls.
Photomicrograph showing networks of capillary vessels with a staghorn-like shape, whose lumen is lined by flat endothelial cells, surrounded by proliferation of fusiform monomorphic cells, with and without atypia (H&E, original magnification ×200).
Immunohistochemical staining of tumor cells shows diffuse and strong positivity for CD34 (original magnification ×200).
Although the prevalent aspect is that of a benign tumor, these forms characteristically have multilobular or irregular margins (6) and may be associated with adjacent bone erosion or destruction (33). In the present case, the tumor had a well-circumscribed margin with no bone erosion or destruction. These tumors can sometimes behave aggressively. Two potentially malignant cases have been reported in the oral cavity: one occurring in the sublingual gland (23) and the other in the tongue (34). Infiltrative aspects are reported, including infiltration of cranial structures or extensive bone destruction (17, 18, 29, 35-38).
HPCs are classified as benign, borderline, and malignant according to the histological (mitotic activity, cellularity and nuclear atypia) and clinical features (necrosis and tumor size) (38). However, the histological distinction between benign and malignant HPCs may be difficult, because the histologic criteria for prediction of biological behavior are imprecise (39). Criteria of malignancy include large tumor size (>50 mm), disseminated disease at presentation, infiltrative margins, high cellularity, nuclear pleomorphism, areas of tumor necrosis and increased mitotic index (>4 mitoses per 10 high-power fields (HPF) (36). Survival is correlated with the grade, size, and margin status (36). The rate of metastasis from cellular HPC/SFT is low, and most patients do not develop local recurrences. However, in an analysis of 45 cases of cellular HPC/SFT of the head and neck, 40% were found to be locally recurrent (17, 18, 29, 35) and 10% had distant metastases (37). Recurrences can often be very delayed. Enzinger and Smith reported that 7 out of 106 patients had recurrence after a disease-free interval of 3 years (38).
Metastases are known to occur in the lung, bone, liver, regional lymph nodes and pancreas (40). Follow-up examination of recurrent lesions should include a chest radiograph. Because of the rarity and unpredictable biological behavior of these tumors, controversy remains about the best way to manage them. The treatment of choice for HPC/SFT when the tumor is localized and technically resectable is wide surgical resection. The usefulness of adjuvant radiation therapy has not been fully demonstrated, although more recent studies suggest that radiation therapy may be useful in some situations (41). In particular, postoperative radiation therapy has been recommended in cases of incomplete surgical removal. The role of chemotherapy in the treatment of cellular HPC/SFT has not been clearly determined in the case of locally non-operative lesions. Perioperative embolization has been suggested as an adjuvant for decreasing tumor vascularity and size (41). A study by Craven et al. (42) encouraged the use of routine angiography and perioperative embolization to reduce intraoperative hemorrhage.
Conclusion
HPC/SFT is a very rare slow-growing vascular tumor, with variable malignant potential, whose biological behavior is difficult to predict. Treatment of choice is wide surgical resection. Adjuvant radiotherapy and chemotherapy can cause tumor regression and in particular, postoperative radiation therapy has been recommended in cases of incomplete surgical removal. Long-term follow-up is necessary even after radical resection because recurrence or metastasis may be delayed by many years.
- Received December 2, 2010.
- Revision received January 10, 2011.
- Accepted January 11, 2011.
- Copyright© 2011 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved
References
In this issue
Jump to section
Related Articles
Cited By...
- No citing articles found.