Sinonasal-type hemangiopericytoma: a clinicopathologic and immunophenotypic analysis of 104 cases showing perivascular myoid differentiation

FDG PET/CT findings of a glomangiopericytoma

Glomangiopericytoma (GPC) is a rare vascular neoplasm that arises almost exclusively from the nasal cavity or paranasal sinuses. GPC is also called sinonasal-type hemangiopericytoma, although current nomenclature, as well as classification in a group with myopericytomas, better emphasizes the relatively indolent behavior of this tumor. The authors present the FDG PET/CT findings of GPC in a 53-year-old with symptoms of nasal congestion and facial pressure. CT and MRI showed a nasal mass to extend along the sphenoid ridge from the posterior nasal cavity into the posterior nasopharynx. PET showed the mass to have uniformly low-grade FDG hypermetabolism. Pathologic examination of the surgical specimen showed classic features of GPC.

Sinonasal-type hemangiopericytoma of the nasal cavity and paranasal sinus

Sinonasal-type hemangiopericytoma is a very rare disease. A 64-year-old man was admitted to our hospital because of nasal obstruction. Nasal endoscopy showed a polyp in the right nasal cavity. Imaging modalities including CT and MRI revealed polypoid tumors in the right nasal cavity and right sphenoid sinus. Excision of the tumors was performed. Macroscopically, the nasal tumor was reddish and focally cystic, and the tumor of the sphenoid sinus was reddish and solid. Microscopically, round and polygonal cells were seen to proliferate monotonously in a medullary fashion. Each tumor cell had a vesicular nucleus and amphophilic cytoplasm. The cellularity was high and mitotic figures were recognized in 6 per 10 high-power fields. Many thin-walled vessels were embedded within the tumor. No collagenization was recognized. A silver stain showed that fine argyrophilic fibers encased individual cells and a few cell nests. Mild invasion into the surrounding tissue was recognized in focal areas. The tumor showed focal cystic and hemorrhagic changes. Immunohistochemically, the tumor cells were positive for vimentin, bcl-2 and factor XIIIa, and negative for cytokeratins, epithelial membrane antigen, CD34, desmin, α-smooth muscle antigen, myoglobin, myogenin, CD31, KIT, p53 protein, CD99, and factor VIII-related antigen. Ki-67 labeling was 17%. The pathological diagnosis was low-grade malignant sinonasal-type hemangiopericytoma. The patient was followed up, but no recurrence has been seen 4 years after the operation.

An immunohistochemical study of sinonasal hemangiopericytoma

We present herein the imaging and pathological features of a 28-year-old male with a sinonasal hemangiopericytoma-like tumor occupying the left nasal meatus. At the initial visit, a nasal polyp was suspected, but, as the patient was bleeding readily, an angiomatoid lesion was also regarded as a possible diagnosis. Based on a thorough histopathological analysis, a sinonasal hemangiopericytoma-like tumor was diagnosed. Hematoxylin and eosin staining also showed a mild degree of nuclear pleomorphism and a slight increase in mitotic activity, and immunohistochemical studies using anti-CD34, MIB-1, and Vimentin antibodies were useful for distinguishing the hemangiopericytoma-like tumor from true hemangiopericytoma and a solitary fibrous tumor.

Glomangiopericytoma of the nasal cavity

Glomangiopericytoma is a rare tumor arising from the pericytes surrounding capillaries, and accounts for less than 0.5% of all sinonasal tumors. A 60-year-old male patient presented with a glomangiopericytoma of the nasal cavity manifesting as nasal obstruction and epistaxis, which was treated successfully with endoscopic excision. Histological examination showed multiplication of spindle-shaped to oval cells which reacted strongly to immunostaining for α-smooth muscle actin. Glomangiopericytoma is categorized as a borderline low malignancy tumor, which tends to recurrence. Strict follow-up is required, especially if complete resection is not achieved.

Sinonasal glomangiopericytoma: case report with emphasis on the differential diagnosis

Glomangiopericytoma (sinonasal-type hemangiopericytoma) is an uncommon sinonasal neoplasm with a perivascular myoid phenotype. This tumor differs from conventional soft tissue hemangiopericytoma in location, biologic behavior, and histologic features. The proposed cell of origin is a modified perivascular glomuslike myoid cell. Glomangiopericytoma is an indolent tumor that tends to arise in the sinonasal tract of older adults and has a low malignant potential with excellent prognosis after surgical resection. Histologically, this lesion is composed of a diffuse, subepithelial proliferation of bland, uniform, closely packed spindled cells growing in a variety of patterns. A distinctive vascular network composed of variably sized vascular channels, the smaller of which demonstrate perivascular hyalinization, is often present. We report the case of a 48-year-old woman with epistaxis and nasal obstruction who was diagnosed with glomangiopericytoma and discuss the histologic differential diagnosis.

Endoscopic, endonasal management of sinonasal haemangiopericytoma: 12-year experience

AIM

To report our experience with endoscopic, endonasal management of sinonasal haemangiopericytoma.

MATERIALS AND METHODS

Retrospective review of the medical records of 10 patients undergoing endoscopic, endonasal surgery for sinonasal haemangiopericytoma of the nose and paranasal sinuses, between 1997 and 2008.

RESULTS

Five men and five women were included. Their mean age at surgery was 59 years. All patients underwent endoscopic, endonasal resection of their tumour. Major post-operative complications were encountered in only one patient (stroke). Local recurrence was diagnosed in only one patient (10 per cent), who subsequently underwent a combined resection (endoscopic and external) with orbital exenteration.

CONCLUSIONS

Sinonasal haemangiopericytomas are rare tumours that are usually benign. The mainstay of treatment is wide surgical excision with free resection margins. Nowadays, the great majority of patients can be treated using a purely endoscopic, endonasal approach.

Minute myopericytoma of the neck: a case report with literature review and differential diagnosis

Reports of cutaneous myopericytoma (MPC) are very rare. The author herein reports a case of minute MPC of the neck. A 56-year-old woman noticed a painful small tumor in the neck, and consulted to our hospital. Dermatologists's diagnosis is a hyperplastic lymph node. Excision of the tumor was performed. Grossly, the tumor was a sold white tumor measuring 3 × 3 × 3 mm. Microscopically, it consisted of many vascular channels and perivascular cell proliferation encased by a fibrous capsule. The vascular proliferation showed a hemangiopericytoma (HPC)-like pattern such as staghorn-like vessels. Fibrosis was not present. The HPC-like cells had vesicular nuclei and polygonal cytoplasm. No atypia is recognized. The HPC-like cells focally showed vague nodular proliferation around the vessels. Immunohistocheically, the tumor cells were negative for cytokeratin, and positive for vimentin. The vasculatures were positive for factor VIII-related antigen, CD34, and CD31. The HPC-like tumor cells were positive for α-smooth muscle actin and h-caldesmon, but negative for desmin, S100 protein, melanosome, bcl-2, CD99, and KIT. The Ki-67 labeling was 8% and p53 was negative. The pathologic diagnosis was MPC of the neck skin. The patient is now alive without recurrence 4 years after the excision. A review of the literature revealed 73 cases of MPC from 6 papers. MPC is male predominance, and the patients ages ranges from 13 to 87 years with the median of 47 years. The most common location was lower extremities followed in order by upper extremities, head and neck, and trunk. One MPC occurred within the vasculature, and 3 cases of MPC developed in the scar or trauma lesions. The prognosis after excision is good, but a very minority showed local recurrence. A differential diagnosis was also made.

[Fibroblastic and myofibroblastic tumors of the head and neck]

Fibroblastic and myofibroblastic tumors of the head and neck are numerous and may develop either in adults or in childhood. They can be benign and nonrecurring, benign but locally recurring, of low-grade of malignancy or fully malignant. The diagnosis and treatment of these lesions can be difficult. This review focuses on several (myo)fibroblastic lesions of the head and neck, including nodular fasciitis and related neoplasms, hemangiopericytoma-like tumor (glomangiopericytoma) of sinonasal passages, nasopharyngeal angiofibroma, desmoid fibromatosis, Gardner-associated fibroma, extrapleural solitary fibrous tumor, inflammatory myofibroblastic tumor, low-grade myofibroblastic sarcoma, and adult-type fibrosarcoma.

Solitary fibrous tumor of the oral cavity: clinicopathologic and immunohistochemical study of 21 cases

We describe clinical, morphologic, and immunohistochemical features of 21 cases of solitary fibrous tumor presenting in the oral cavity. There were 9 male and 12 female patients with a median age of 51 years (range 37-83). The most common locations included the buccal mucosa (the most common site), lip, maxillary or mandibular vestibule and tongue. Histopathologic examination showed well-circumscribed tumors with two well-defined patterns: the classic pattern with densely cellular areas alternating with hypocellular areas in a variably collagenous, vascular stroma and a more uniformly sclerotic pattern with only subtle classic areas. The spindle-shaped neoplastic cells consistently showed immunoreactivity for antibodies directed against CD34. Five of nineteen cases (26%) were reactive for CD99 and 19 of 19 for Bcl-2. Follow-up information was available in 17 cases and averaged 54 months, with no evidence of recurrence or metastasis in any of these patients. Awareness that solitary fibrous tumor may present in the oral cavity is important so that confusion with other spindle cell neoplasms can be avoided. We also briefly describe the differential diagnosis and compare this series, the largest single series of intraoral SFT, to cases previously reported in the literature.

Nasenhöhle und Nasennebenhöhlen

Die Gesichtsmitte (der Bezirk zwischen Oberlippe und Stirn) entwickelt sich zwischen der 4. und 8. Schwangerschaftswoche. [ 220] Der Stirnfortsatz bildet sich währen der 4. postovulatorischen Woche, aus ihm gehen die oberen und mittleren Anteile des Gesichts hervor. Die Oberkiefer- und Nasenwülste entwickeln sich unterhalb des Stirnfortsatzes. Am Ende der 4. Woche bilden zwei oberflächliche Verdickungen der Nasenwülste die Riechplakoden, die ektodermaler Herkunft sind und aus denen der Epithelbelag der Nasenhöhle und Nasennebenhöhlen hervorgeht. Die Plakoden stülpen sich ein und bilden die Riechgruben, aus denen die vorderen Choanen (Nasenlöcher) und weniger oberflächlich die primitiven hinteren Choanen entstehen. Die medialen Nasen- und Stirnfortsätze bilden das Nasenseptum, die Stirnknochen, Nasenknochen, die Siebbeinzellen- Komplexe und die oberen Schneidezähne. Die lateralen Nasen- und Oberkieferfortsätze vereinigen sich zur Bildung des Philtrum und der Columella. Das knorpelige Nasenskelet bildet sich während der 7. und 8. postovulatorischen Woche tief unterhalb der Nasen- und Stirnbeinknochen aus dem Chondrocranium. Die Nasennebenhöhlen entwickeln sich in der 6. Fetalwoche aus den lateralen Nasenwänden, und ihr Wachstum setzt sich nach der Geburt während des gesamten Kindes- und Jugendalters fort.

Rare nasosinusal tumors: case series and literature review

Tumors of the nasal cavity and paranasal sinuses are unusual pathologies found in clinical practice. Approximately 0.8% of all human cancers are located in this area. Despite being rare, nasosinusal neoplasms usually manifest through nonspecific symptoms that are common to numerous inflammatory pathologies. The aim of this study is to describe a series of rare nasosinusal tumors, including esthesioneuroblastomas, central giant cell granulomas, extramedullary plasmocytomas, nasosinusal hemangiopericytomas, neurofibromas and cemento-ossifying fibromas, diagnosed at the Fortaleza General Hospital. We, hereby, briefly review each of the aforementioned pathologies, stressing the need for a precise histological diagnosis for proper treatment in each case.

Solitary fibrous tumor of the larynx

BACKGROUND

True mesenchymal, non-cartilaginous neoplasms of the larynx are rare. Extrapleural solitary fibrous tumor (SFT) is a localized neoplasm characterized by proliferation of thin-walled vessels and collagen-producing cells and is considered within the "hemangiopericytoma-solitary fibrous tumor" spectrum. SFT primary in the larynx is exceptional.

DESIGN

Case report set in a comparison with other cases reported in the English literature (MEDLINE 1966 to 2007).

RESULTS

A 49-year old white male presented with difficulty breathing, progressive over the past 2 years. He denied dysphagia and weight loss. Past medical history was significant for asthma. He denied cigarette smoking or alcohol abuse. There were no cervical deformities on physical exam. Fiberoptic laryngoscopy was performed upon stabilization of respiratory function. A smooth, round, submucosal mass measuring 2.3 cm in greatest diameter arising from the inferior surface of left true vocal cord was causing near total obstruction of the endolaryngeal space. The mass was excised. The surface mucosa was intact and unremarkable. A cellular, spindle cell neoplasm was arranged in loose fascicles, associated with heavy collagen fiber deposition. The collagen was wiry and heavy. Cells were bland with cytoplasmic extensions. The nuclei were vesicular to hyperchromatic and elongated with inconspicuous nucleoli. Vessels were prominent and delicate, with patulous spaces. Mitotic figures were easily identified, but atypical forms were not present. The cells were strongly and diffusely immunoreactive with CD34 and bcl-2, while non-reactive with cytokeratin, EMA, actin, ALK-1, S100, desmin, and CD117. These findings confirmed a diagnosis of extraplural solitary fibrous tumor. Without further disease, the patient is alive without evidence of disease, 12 months after surgery.

CONCLUSIONS

The characteristic histologic pattern of solitary fibrous tumor can be noted in extrapulmonary locations. Development in the larynx is uncommon, but the tumor presents as a polypoid mass with characteristic histologic and immunophenotypic features. Conservative local excision is the treatment of choice to yield an excellent prognosis.

Tumores nasossinusais raros: série de casos e revisão de literatura

Os tumores nasossinusais são patologias pouco freqüentes na prática clínica. Aproximadamente 0,8% de todos os cânceres humanos localizam-se nessa região. Apesar de rara, a neoplasia nasossinusal manifesta-se habitualmente através de sintomas inespecíficos e comuns a inúmeras patologias inflamatórias. Este estudo se propõe a descrever uma série de casos de tumores nasossinusais não-epiteliais raros, incluindo estesioneuroblastoma, granuloma central de células gigantes, plasmocitoma extramedular, hemangiopericitoma sinonasal, neurofibroma e fibroma cemento-ossificante, diagnosticados no Hospital Geral de Fortaleza, SESA/SUS. Faz-se uma breve revisão de literatura de cada patologia, salientando-se a necessidade do diagnóstico anatomopatológico preciso para condução adequada de cada caso.

[Sinonasal hemangiopericytomas]

OBJECTIVES

The aim of this study was to report on the clinical, radiological and histological characteristics of hemangiopericytomas, and to discuss our experience with their treatment.

MATERIAL AND METHODS

The authors reexamined two recent cases of patients presenting with sinonasal hemangiopericytomas (semiology, CT and MRI results, treatment and follow-up).

RESULTS AND DISCUSSION

There was substantial variability of hemangiopericytoma presentation depending on location. Hemangiopericytomas of the nose and paranasal sinuses are considered a distinct entity with a good prognosis. Treatment is based on endoscopic sinus surgery. The histological approach requires the use of immunohistochemistry. Recurrences vary in the literature depending on the initial resection quality. Metastases are rare.

Sinonasal tract angiosarcoma: a clinicopathologic and immunophenotypic study of 10 cases with a review of the literature

BACKGROUND

Primary sinonasal tract angiosarcoma are rare tumors that are frequently misclassified, resulting in inappropriate clinical management. There are only a few reported cases in the English literature.

MATERIALS AND METHODS

Ten patients with sinonasal tract angiosarcoma were retrospectively retrieved from the Otorhinolaryngic Registry of the Armed Forces Institute of Pathology.

RESULTS

Six males and four females, aged 13 to 81 years (mean, 46.7 years), presented with epistaxis and bloody discharge. Females were on average younger than their male counterparts (37.8 vs. 52.7 years, respectively). The tumors involved the nasal cavity alone (n = 8) or the maxillary sinus (n = 2), with a mean size of 4.3 cm; the average size was different between the genders: males: 2.8 cm; females: 6.4 cm. Histologically, all tumors had anastomosing vascular channels lined by remarkably atypical endothelial cells protruding into the lumen, neolumen formation, frequent atypical mitotic figures, necrosis, and hemorrhage. All cases tested (n = 6) demonstrated immunoreactivity with antibodies to Factor VIII-RA, CD34, CD31, and smooth muscle actin, while non-reactive with keratin and S-100 protein. The principle differential diagnosis includes granulation tissue, lobular capillary hemangioma (pyogenic granuloma), and Kaposi's sarcoma. All patients had surgery followed by post-operative radiation (n = 4 patients). Follow-up was available in all patients: Six patients died with disease (mean, 28.8 months); two patients had died without evidence of disease (mean, 267 months); and two are alive with no evidence of disease at last follow-up (mean, 254 months).

CONCLUSIONS

Sinonasal tract angiosarcoma is a rare tumor, frequently presenting in middle-aged patients as a large mass usually involving the nasal cavity with characteristic histomorphologic and immunophenotypic features. Sinonasal tract angiosarcoma will often have a poor prognosis making appropriate separation from other conditions important.

Intranasal myopericytoma. A tumour with perivascular myoid differentiation: the changing nomenclature for haemangiopericytoma

We present a case report of a patient who developed a sinonasal myopericytoma treated by surgical excision through a lateral rhinotomy. Some aggressive features on pre-operative computed tomography scanning and the complexity of recent changes in the histological nomenclature for these tumours led to consideration of adjuvant therapy. The close histological relationship between myopericytoma, myofibromatosis, solitary myofibroma and infantile haemangiopericytoma is discussed. This group of lesions constitute a single morphological spectrum with differentiation towards perivascular myoid cells (pericytes). Currently myopericytoma is the most appropriate and accepted term embracing all these entities. A review of the literature has been reassuring in identifying these tumours as benign but with a reasonably high rate of local recurrence (17 per cent). The treatment of choice is surgical excision with further excisions for local recurrence.

Glomangiopericytoma of the pterygomandibular space: an unusual case

We describe a case of glomangiopericytoma located in the pterygo-mandibular space, a rare anatomical region for this neoplasm to develop. The lesion is classified as a separate variant from the classic haemangiopericytoma, which is characterised by more aggressive biological behaviour.

Solitary fibrous tumour and haemangiopericytoma: evolution of a concept

Haemangiopericytoma (HPC) was described in 1942 by Stout and Murray as a distinctive soft tissue neoplasm, presumably of pericytic origin, exhibiting a characteristic well-developed "staghorn" branching vascular pattern. Over the years, it appeared that this growth pattern was a non-specific one, shared by numerous, unrelated benign and malignant lesions, and that HPC was better considered as a diagnosis of exclusion. Three categories of lesion may now be individualized within the heterogeneous group of HPC-like neoplasms. The first category corresponds to those non-HPC neoplasms that occasionally display HPC-like features (e.g. synovial sarcoma). Lesions belonging to the second category show clear evidence of myoid/pericytic differentiation and correspond to true HPCs. They generally show a benign clinical course, and include glomangiopericytoma/myopericytoma, infantile myofibromatosis (previously called infantile HPC), and a subset of sinonasal HPCs. The third category is the solitary fibrous tumour (SFT) lesional group, which includes fibrous-to-cellular SFTs, and related lesions such as giant cell angiofibromas and lipomatous HPCs. In practice, any HPC-like lesion can be allocated to one of these categories, leaving the ill-defined "haemangiopericytoma" category empty.

Endoscopic Resection of Sinonasal Hemangiomas and Hemangiopericytomas

INTRODUCTION

Endoscopic resection of benign neoplasms, such as inverted papilloma, has been well described. There are limited case reports of endoscopic resection of benign vascular tumors, including hemangiomas, or those with low-grade malignant potential, such as hemangiopericytomas.

METHODS

Retrospective review of sinonasal hemangiomas and hemangiopericytomas resected endoscopically at a single tertiary-care facility.

RESULTS

Three hemangiomas and 3 hemangiopericytomas were resected endoscopically with no recurrences at a mean follow-up of 22 months. Four tumors involved the skull base; 2 of these underwent preoperative embolization. One patient had a CSF leak that occurred as the tumor was removed from the cribriform plate and that was successfully repaired intraoperatively. The average size of the tumors was 5.8 cm x 2.7 cm with all tumors at least 2.5 cm in greatest dimension by computed tomography or magnetic resonance imaging. The largest tumor was 12 cm in greatest dimension. An average of 8 intraoperative frozen section margins was taken around 5 tumors, with all margins of each tumor clear on final pathology. Patients included 4 males and 2 females with an average age of 47 years.

CONCLUSION

Large vascular neoplasms of the sinonasal cavity, such as hemangiomas and hemangiopericytomas, can be safely removed using endoscopic techniques. Although these patients have a limited follow-up, it is prudent to perform long-term endoscopic follow-up in order to detect recurrences regardless of resection technique.

D2-40 staining in sinonasal-type hemangiopericytoma--further evidence of distinction from conventional hemangiopericytoma and solitary fibrous tumor

D2-40 is a monoclonal antibody, which reacts with a fixative-resistant epitope of lymphatic endothelium. Sinonasal-type hemangiopericytoma (SHP) and tumors of the (conventional) hemangiopericytoma/solitary fibrous tumor family (HP/SFT) are characterized by prominent vasculature. However, data concerning D2-40 labeling of these tumors are very sparse. In the present study, we investigated D2-40 staining in tissue specimens of 17 patients with SHP (male to female ratio of 2.4:1, median age of 63 years) and compared the immunolabeling with 20 cases of HP/SFT, including three SFT cases from nasal mucosa. D2-40 was detected in vascular channels of all SHP patients examined. By contrast, all cases of HP/SFT did not reveal any vascular channel being positive for D2-40, neither in the nasal cases nor in the remaining patients. This study presented for the first time data on D2-40 labeling in a series of SHP, HP/SFT, and supports the distinction of SHP from HP/SFT.

Ultrastructural spectrum of solitary fibrous tumor: a unique perivascular tumor with alternative lines of differentiation

Eight tumors diagnosed as solitary fibrous tumor (SFT) of the oral cavity were studied. Histologic spectrum was entirely comparable with the extrapleural SFT of other sites. One tumor had glomus tumor-like foci. Immunohistochemical results confirmed most of the previous observations, indicating characteristic expression of vimentin, CD34, bcl-2, and CD99. Factor XIIIa and alpha-smooth muscle actin were less commonly reactive and a very few cells were faintly positive for factor VIII-related antigen and Ulex europaeus agglutinin 1. All were essentially negative for S-100 protein, desmin, CD31, and CD68. In stark contrast to the conclusive immunoprofile, ultrastructural investigation of six tumors demonstrated considerable cellular heterogeneity. Other than fibroblasts, perivascular undifferentiated cells and pericytes predominated, but endothelial cells were regularly present. There was a distinctive proliferation of pericytic cells in four tumors, one of which had glomoid foci of myopericytes. The extreme increase in number of Weibel-Palade bodies occurred in voluminous capillary endothelium. Occasional single and clustered cells with consistent features of endothelium showed intracytoplasmic lumen formation. Such composite cells constituted an integral segment of richly vascularized SFT. Myofibroblastic form smooth muscle differentiation was present in only a minority of cells. From phenotypic analysis by electron microscopy, SFT may originate from a unique, perivascular multipotent mesenchyme sharing with its lineage with pericytes, fibroblasts, and infrequently, endothelium. Consequently, morphological features of SFT may become diversely varied by whether predominantly constituent cells are undifferentiated, pericytic or fibroblastic in nature.

Low-grade sarcomas with CD34-positive fibroblasts and low-grade myofibroblastic sarcomas

A subset of low-grade fibrosarcomas is composed of CD34-positive spindle cells. These include dermatofibrosarcoma, its morphologic variants, and its associated fibrosarcoma, solitary fibrous tumor, hemangiopericytoma and their malignant counterparts, and some cases of myxoinflammatory fibroblastic sarcoma. Dermatofibrosarcoma and related lesions are characterized by a t(17;22)(q22;q13) rearrangement resulting in fusion of the genes COL1A (17q21-22) and PDGFB1 (22q13). Solitary fibrous tumor displays varying cellularity and fibrosis and a peripheral hemangiopericytomatous pattern; most tumors formerly called hemangiopericytoma are now subsumed into the category of solitary fibrous tumor, although a few strictly defined examples are recognized; however, these are probably not composed of pericytes. Myofibroblastic malignancies are best identified by electron microscopy, with which varying degrees of differentiation, including the presence of fibronexus junctions, can be identified. Low-grade sarcomas showing myofibroblastic differentiation include myofibrosarcomas and inflammatory myofibroblastic tumors. Myofibrosarcomas are spindle cell neoplasms that occur in children or adults in the head and neck, trunk, and extremities as infiltrative neoplasms and that display a fascicular or fasciitis-like pattern with focal nuclear atypia and variable expression of myoid antigens. These sarcomas are prone to recurrence and a small number metastasize. Inflammatory myofibroblastic tumor (synonymous with inflammatory fibrosarcoma) is a neoplasm arising predominantly in childhood, and frequently in intraabdominal locations. It has spindle cells in fascicular, fasciitis-like and sclerosing patterns, with heavy chronic inflammation including abundant plasma cells. Many IMT have clonal chromosomal abnormalities involving 2p22-24, and fusion of the ALK gene with tropomyosin 3 (TPM3-ALK) or tropomyosin 4 (TPM4-ALK) is found in a subset.

Niedrig-maligne periphere Nervenscheidentumoren der Nasen- und Nasennebenh�hlenschleimhaut

Sinonasal malignant peripheral nerve sheath tumors (MPNST) are infrequent neoplasms. 16 cases of low-malignant MPNST in this localization were retrieved from the files of soft tissue tumors established in Jena. They were examined with regard to their morphology and immunohistochemistry. The importance of an only partial immunostaining by S100 protein antibodies for diagnosis and differential diagnostic discrimination to benign peripheral nerve sheath tumors (schwannomas and neurofibromas) is explained. Finally, the differential diagnosis of spindle cell tumors in the sinonasal region in general is briefly discussed.

Sinonasal Hemangiopericytomas: Clinicopathologic and Imaging Findings

Hemangiopericytomas are rare soft-tissue neoplastic lesions that can arise in any part of the body. They are mesenchymal tumors that account for 3 to 5% of all soft-tissue sarcomas and 1% of all vascular tumors. They originate in extravascular cells (pericytes). Some 15 to 30% of all hemangiopericytomas occur in the head and neck; of these, approximately 5% occur in the sinonasal area. We describe our brief retrospective review of 7 histologically proven cases of sinonasal hemangiopericytoma, and we discuss the imaging characteristics and clinical and pathologic findings in these patients.

[Perivascular neoplasms of skin and soft tissues. A review]

Perivascular neoplasms of skin and soft tissues comprise a group of benign and malignant mesenchymal neoplasms showing a perivascular myogenic differentiation. Whereas glomus tumour including its variants represents a clearly defined clinicopathological entity, the whole concept of haemangiopericytoma has been questioned in the last years, and no clear diagnostic criteria are established at the moment. Myopericytomas and myofibromas represent a morphological spectrum of perivascular spindle-shaped lesions. Infantile myofibroma/infantile myofibromatosis and solitary myofibroma of adults are characterized by a biphasic growth of mature, spindled, myofibroblastic cells and smaller, immature, mesenchymal cells associated with numerous haemangiopericytoma-like vessels. Benign and rare malignant myopericytomas of skin and soft tissues are characterized by a concentric, perivascular growth of plump spindled and round tumour cells staining positively for muscle actin, alpha-smooth muscle actin and more rarely for desmin. PEComas represent an enigmatic family of neoplasms composed of perivascular epithelioid, clear, and spindled tumour cells characterized by a coexpression of melanocytic and myogenic markers.