Epithelioid and Epithelial Neoplasms of Bone

Primary vascular tumors of bone: A comprehensive literature review on classification, diagnosis and treatment

Primary vascular tumors of bone are a heterogeneous group of neoplasms, ranging from benign hemangiomas to frankly malignant epithelioid hemangioendotheliomas and angiosarcomas. Over the years, their classification has been a matter of discussion, due to morphologic similarities and uncertainty regarding biologic behavior. Over the past decade, with the development of next-generation sequencing, there has been a significant improvement in the molecular characterization of these lesions. The integration of their morphologic, immunohistochemical and molecular features has led to a better stratification, with important prognostic and therapeutic implications. Nevertheless, primary vascular bone tumors still represent a challenge for medical oncologists. Given their rarity and heterogeneity, in the last few years, there has been no significant progress in medical treatment options, so further research is needed. Here we present a review of the current knowledge regarding primary vascular tumors of the bone, correlating clinicopathologic features with tumor behavior and therapeutic approaches.

Epithelioid Haemangioma of Bone: A Case Series and Comprehensive Literature Review Reappraising the Diagnostic Classification of All Epithelioid Vascular Neoplasms of Bone

Epithelioid vascular neoplasms of the bone are classified by the World Health Organization (WHO) into only two tiers: low-grade epithelioid hemangioma (EH) and a more malignant category including both epithelioid hemangioendothelioma and epithelioid angiosarcoma. The World Health Organization defines bone EH as a locally aggressive neoplasm with no connotation of benign or intermediate malignancy. We reviewed three cases of EH in our lab archives with the perspective of appraising their histomorphological approach toward diagnosis. Patients were in the age range of 15-25 years. The site of the neoplasms ranged from the carpal bones to the metatarsal bones. Histomorphological examination of the lesions showed a nodular growth pattern of a vascular neoplasm without demonstrable vessel origin. The vasoformative area increased from the center to the periphery, with prominent epithelioid morphology of the endothelial cells at the periphery and an associated inflammatory infiltrate comprising eosinophils, lymphocytes, and plasma cells. The growth pattern was diffuse, with extension into the deeper dermis of overlying skin.

GATA-3 expression in a de-differentiated chondrosarcoma with cutaneous iatrogenic implantation: a diagnostic pitfall with important clinical implications

De-differentiated chondrosarcoma (DDCS) is an extremely aggressive tumor of the bone characterized by a high-grade, non-chondroid sarcoma adjacent to a low- or intermediate-grade chondrosarcoma. Adequate tumor sampling demonstrating the biphasic features is necessary to make an accurate diagnosis. The diagnosis may be challenging as histopathology may mimic other neoplasms. We present a case of a 76-year-old woman with a history of breast cancer who presented with a pathologic non-displaced fracture. A bone biopsy demonstrated a high-grade neoplasm composed of pleomorphic spindled and epithelioid cells with focal expression of AE1/3 and GATA3, most likely consistent with metastatic breast carcinoma. After a difficult clinical course, the tumor was resected demonstrating a similar morphology to her prior biopsy, as well as an area of a low-grade cartilaginous neoplasm consistent with chondrosarcoma. The biphasic tumor alongside a low-grade chondrosarcoma allowed for a diagnosis of DDCS. Several days after her procedure, the patient developed violaceous nodules overlying and surrounding the surgical site. Skin biopsy demonstrated a malignant epithelioid neoplasm with identical histomorphologic features identical to her prior bone resection. Given the location of the skin lesions directly within the surgical site right after resection, the clinical-pathological picture was that of sarcomatosis cutis by iatrogenic cutaneous implantation.

A case of primary distal-type epithelioid sarcoma of the lumbar vertebra with a review of literature

Epithelioid sarcoma (EpS) is a rare malignant neoplasm that accounts for < 1% of adult soft tissue sarcomas. Primary EpS of the bone is extremely rare and only a few cases have been reported to date. We report a case of primary distal-type EpS of the lumbar vertebra. A 30-year-old man without any history of malignant tumors had complained of lumbago for 3 months before visiting the hospital. Magnetic resonance imaging (MRI) of the lumbar spine showed a high signal intensity on the fat-suppressed T2-weighted image (WI) and a low signal on the T1WI at the L1 vertebral body. The tumor protruded toward the anterior components. Systemic radiological examination revealed no other lesion. A biopsy revealed a primary malignant tumor with epithelioid features. After chemotherapy, total en bloc spondylectomy was performed. Macroscopically, the tumor replaced the entire L1 with necrosis. Histologically, the tumor showed nodules of epithelioid cells that were strongly positive for epithelial markers, but a lack of INI1 expression. Central necrosis in the tumor nodule was also observed. This tumor showed loss of heterozygosity at the SMARCB1 locus but without the SMARCB1 mutation. The result of Foundation One ®CDx showed no actionable mutations. Seven months after surgery, a subcutaneous metastasis to the left cheek and bilateral lung metastasis with pleural dissemination were observed on radiological examination. A final diagnosis of distal-type EpS was made based on these findings. The patient died of the disease 8 months after surgery.

FOS-ANKH and FOS-RUNX2 Fusion Genes in Osteoblastoma

BACKGROUND/AIM

Osteoblastoma is a rare benign tumor of the bones in which recurrent rearrangements of FOS have been found. Our aim was to investigate two osteoblastomas for possible genetic aberrations.

MATERIALS AND METHODS

Cytogenetic, RNA sequencing, and molecular analyses were performed.

RESULTS

A FOS-ANKH transcript was found in the first tumor, whereas a FOS-RUNX2 was detected in the second. Exon 4 of FOS fused with sequences either from intron 1 of ANKH or intron 5 of RUNX2. The fusion events introduced a stop codon and removed sequences involved in the regulation of FOS.

CONCLUSION

Rearrangements and fusions of FOS show similarities with those of HMGA2 (a feature of leiomyomas and lipomas) and CSF1 (tenosynovial giant cell tumors). The replacement of a 3'-untranslated region, controlling the gene's expression, by a new sequence is thus a common pathogenetic theme shared by FOS, HMGA2, and CSF1 in many benign connective tissue tumors.

Fusion of the COL1A1 and FYN Genes in Epithelioid Osteoblastoma

BACKGROUND/AIM

Epithelioid osteoblastoma is a rare benign tumor of the bone. Its pathogenesis is unknown and little is known regarding its genetic features.

MATERIALS AND METHODS

Cytogenetic, RNA sequencing, reverse transcription polymerase chain reaction (RT-PCR), genomic PCR, and Sanger sequencing analyses were performed on an epithelioid osteoblastoma.

RESULTS

G-banding analysis of short-term cultured tumor cells yielded a normal male karyotype in all examined metaphases. RNA sequencing detected a fusion of COL1A1 from 17q21 with FYN from 6q21. Both RT-PCR and genomic PCR together with Sanger sequencing verified the presence of a COL1A1-FYN fusion gene. In the COL1A1-FYN chimeric transcript, exon 43 of COL1A1 was fused to exon 2 of FYN. The genomic junction occurred in introns 43 and 1 of COL1A1 and FYN, respectively.

CONCLUSION

A COL1A1-FYN fusion gene was found in an epithelioid osteoblastoma resulting in deregulation of FYN. Whether COL1A1-FYN represents a consistent genetic feature of epithelioid osteoblastomas, remains to be seen.

Metachronous extraskeletal (soft tissue) epithelioid osteogenic sarcoma: a case report

Background

Metachronous osteosarcoma is a rare form of osteosarcoma. The occurrence of metachronous tumor in soft tissue is exceedingly rare. The pathogenesis of metachronous osteosarcoma, as to whether it represents multiple true primaries or metastatic disease, is still obscure.

Case presentation

A 49-year-old Indian man presented with progressively increasing swelling in his left hand of 2 months’ duration. An X-ray showed a soft tissue lesion. Contrast-enhanced computed tomography showed a soft tissue mass lesion, with peripheral enhancement and central necrotic areas in radial palmar soft tissue overlying second metacarpophalangeal region with no obvious bony osteolysis. Possibilities of acute abscess, resolving hematoma, or aggressive soft tissue mass lesion were suggested. An incision biopsy showed morphological features of epithelioid osteosarcoma, which was confirmed on immunohistochemistry. A detailed history revealed that our patient was diagnosed as having osteosarcoma of his right leg 3 years previously. Based on history, radiology, morphology, and immunohistochemistry, a final diagnosis of extraskeletal (soft tissue) epithelioid osteogenic sarcoma of the left hand occurring as a metachronous tumor 3 years after diagnosis of primary osteosarcoma in the right leg was given.

Conclusion

This is probably the first reported case of extraskeletal (soft tissue) epithelioid osteosarcoma occurring as a metachronous tumor 3 years after diagnosis of primary osteosarcoma in the right leg. The prognosis of metachronous skeletal osteosarcoma is poor as compared to that of relapse limited to lungs. In late metachronous osteosarcoma, combined-modality therapy comprising surgery and aggressive chemotherapy may affect long-term survival. Lifelong follow-up of surviving patients with osteosarcoma is necessary and if metachronous osteosarcoma is discovered, it should be treated with curative intent.

Electronic supplementary material

The online version of this article (10.1186/s13256-019-2070-3) contains supplementary material, which is available to authorized users.

Primary Epithelioid Sarcoma of the Zygomatic Bone

Primary epithelioid sarcoma (ES) of bone is extremely rare with only 2 reported cases in the English literature. A previously healthy 18-year-old man presented with a 6-month history of right facial numbness and tingling and right eye diplopia. A computerized tomography scan revealed an ill-defined mass with dense osseous matrix centered in the right zygomatic bone. An outside biopsy was read as osteosarcoma. The resection specimen revealed large epithelioid and spindle cells embedded in a prominent hyalinized matrix with focal metaplastic bone formation. The tumor cells were strongly and diffusely positive for AE1/AE3 and epithelial membrane antigen, but a definitive diagnosis of ES was not immediately reached due to the presence of dense hyalinized matrix and weak expression of SAT2B by tumor cells. Deficient INI1 protein expression by immunohistochemistry and homozygous loss of the SMARCB1 gene by chromosomal microarray analysis ultimately justified this tumor's designation as ES.

Giant periosteal aggressive epithelioid osteoblastoma: 21-year-old male presents case in the midshaft of his femur

We report a rare case of giant periosteal osteoblastoma in the femur of a 21-year-old male. The patient presented with a painful, firm, non-tender mass in his left thigh. The pain was worse at night and was temporarily relieved with NSAIDS. He had no fevers, night sweats, or weight loss. The patient underwent preoperative radiological studies including plain radiographs, MRI, bone scan, and CT scan. An open biopsy was subsequently performed that was consistent with an aggressive, epithelioid osteoblastoma. Pathology demonstrated a neoplasm characterized by cohesive sheets of epithelioid osteoblasts, mixed with areas of conventional osteoblastoma displaying prominent osteoblastic rimming of woven bone trabeculae in a fibrovascular stroma. The patient subsequently underwent resection, cryosurgery, fixation, and bone grafting with cortical strut allografts. At final follow-up, 32 months postoperatively, there was no evidence of local recurrence. The patient had resumed all his normal activities. He could run without pain and had no restrictions with activities. The goal of this case report is to aid professionals in the diagnosis and treatment of highly uncommon aggressive osteoblastomas.

Fibroblastic osteosarcoma with epithelioid and squamous differentiation in a dog

A fibroblastic osteosarcoma with epithelioid and squamous differentiation in the distal femur of a 9-y-old spayed female Greyhound dog is described. Grossly, the tumor consisted of a pale-white, firm-to-hard mass that replaced the medullary and cortical areas of the distal end of the right femur. Histologically, the mass was composed predominantly of spindle cells admixed with areas of mineralized and non-mineralized osteoid matrix that were surrounded by stellate osteoblasts and scattered multinucleate giant cells, consistent with the diagnosis of a fibroblastic osteosarcoma. In addition, well-demarcated clusters of neoplastic epithelioid cells and foci of squamous differentiation with keratin pearls were present throughout the neoplasm. The spindle cells, epithelioid cells, and areas of squamous differentiation expressed cytoplasmic immunostaining for osteocalcin and osteonectin. The spindle cells and epithelioid cells were also immunopositive for vimentin. Epithelioid cells also expressed occasional cytoplasmic immunostaining for pancytokeratin (PCK) Lu-5, and areas of squamous differentiation were immunoreactive for PCK Lu-5 and high molecular weight CK; these areas were inconsistently immunoreactive for CK 5-6 and immunonegative for low molecular weight CK. Foci of squamous differentiation were not located within blood or lymphatic vessels, given that no immunoreactivity for factor VIII-related antigen was observed around these areas. A thorough autopsy and an evaluation of the medical history excluded a primary carcinoma or other neoplasm elsewhere in the dog. The findings were consistent with a diagnosis of fibroblastic osteosarcoma with epithelioid and squamous differentiation.

Epithelioid Angiosarcoma in Femur: A Case Presentation

Primary malignant vascular tumors which constitute less than 1% of the primary bone tumors are very rarely encountered. Epithelioid angiosarcoma is a very uncommon subtype of angiosarcomas presenting with an epithelioid phenotype and mimicking carcinomas clinically. These tumors select mostly extra-skeletal locations but rarely bones as their medium. A 31-year-old male patient applied to our clinic with a nonspecific left hip pain. X-ray evaluation revealed a cystic expansile mass in the trochanteric region of the femur extending to the femoral neck. Computed tomography examination proved that the mass was cystic and 7 cm in its greatest width and contained septum. Moreover, magnetic resonance imaging examination was reported as a mass resembling aneurysmal bone cyst. The final diagnosis of epithelioid angiosarcoma was made by histological examination and biopsy of the mass. The excised specimen was examined further to verify the preoperative diagnosis.

[Lymph node metastasis of osteosarcomas]

Lymph node metastasis of osteosarcomas is a rather rare phenomenon; according to different authors, the incidence of lymph node metastasis is 4 to 11%. The detection of lymph node metastases in osteosarcoma is associated with a significant reduction in the 5-year survival of patients and allows its classification as clinical stage IV tumor. The risk factors for lymph node metastases in patients with bone sarcomas are age (≥64 years), gender (female), nosological entity (undifferentiated pleomorphic sarcoma, osteosarcoma, chondrosarcoma), tumor depth (muscle, bone), and the size of primary tumor (>5 сm). The mechanism of lymph node metastasis of osteosarcomas seems to be related to mesenchymal-to-epithelial transition.

Epithelioid hemangioendothelioma of the proximal phalanx of the left second toe - a rare occurence

INTRODUCTION

Epithelioid hemangioendothelioma (EHE) of the bone is extremely rare and occurs predominantly in males. It most frequently occurs during the second and third decades of life. The lower extremities are most commonly involved. We describe a diagnostically challenging case of epithelioid hemangioendothelioma of proximal phalanx of 2nd toe of left foot with histological features reminiscent of osteoblastomatosis.

CASE REPORT

A 52 year old man presented with history of intermittent pain with swelling in second toe since 6 months. Radiograph showed a lytic lesion in proximal phalanx of the great toe. CT and MRI reported non specific lesion in the toe. Pain was quite severe and as the patient was a labourer and wanted to get back to his work as soon as possible a decision of disarticulation of the second toe at metatarsophalnageal joint was taken. Histopathology confirmed the diagnosis of Epithelioid hemangioendothelioma and patient was called for regular follow up. There are no complications and recurrence at two year follow up.

CONCLUSION

EHE of the bone is extremely rare vascular tumor. To our knowledge, this is the first case of EHE with such features. EHE should be kept as one of the important differential diagnosis while diagnosing vascular tumors. Careful attention to the histopathological features is necessary for the confirmation of the diagnosis.

The debate is still open; benign or malignant: a case report of a multifocal epithelioid haemangioma of fibula

In this case, we report an epithelioid haemangioma (EH) of the fibula with ill-defined multifocal lesions and a resultant pathologic fracture. Based on radiographic appearance, these lesions were initially thought to represent a malignant process, such as primary malignant bone tumour, metastases or multiple myeloma. Osseous EHs are rare. Although they can present as multifocal lesions, the majority of bony EHs are solitary and arise in the diaphysis or metaphysis of long tubular bones, with a predilection for the lower extremity. Non-specific radiological findings, debatable cytological appearance and unpredictable clinical growth patterns commonly cause misdiagnosis of malignancy. To the best of our knowledge, a case of EH with multiple growing lesions of the fibula has not yet been reported in the literature.

Epithelioid Osteosarcoma of the Maxilla

Epithelioid osteosarcoma is an uncommon variant; only 4 cases have been reported in the jaw area, 2 of which were in the maxilla. A 22-year-old woman, in the eighth month of pregnancy, presented to the oral surgery clinic with a mass in the right maxilla that had rapidly expanded over the past 3 months. Computed tomography scans showed an ill-defined sclerotic destructive lesion that formed bone matrix in its soft tissue extension. Microscopic examination of the lesion revealed malignant epithelioid cells with osteoid deposits. The tumor cells were shown to have pale cytoplasm, vesicular nuclei, and prominent nucleoli and to undergo frequent mitosis. In addition, the tumor was positive for epithelial membrane antigen and vimentin and negative for AE1/AE3, Melan-A, CD30, synaptophysin, NSE, CD45, CD99, desmin, and myogenin. The final diagnosis was epithelioid osteosarcoma, which is a rare aggressive variant of osteosarcoma. Few cases of epithelioid osteosarcoma have been reported in the literature, and more studies are required to determine the clinical behavior of this tumor.

The myriad of diseases that present with polyostotic bone lesions

Many diseases result in polyostotic bone lesions including benign entities, benign entities with malignant potential, intermediate entities, and malignant entities. Imaging plays a key role in identifying complications of these disorders, most importantly malignant transformation of a benign lesion. The most common polyostotic bone lesions are reviewed and examples of malignant transformation are highlighted.

Aggressive clinical course of epithelioid angiosarcoma in the femur: a case report

Background

Epithelioid angiosarcoma is a rare variant of angiosarcoma, and is characterized by an epithelioid morphologic appearance that mimics carcinoma. These tumors usually arise in extraskeletal sites; origination in bone is rare.

Case presentation

A 69-year-old woman presented with right knee pain. Plain radiographs and magnetic resonance imaging showed an osteolytic lesion with a large soft-tissue extension into the distal femur. Under a diagnosis of metastatic carcinoma of unknown origin based on the biopsy specimen, resection and replacement with an artificial joint were performed. Histologic analysis of the resected material confirmed epithelioid angiosarcoma, supported by immunoexpression of cytokeratins and vascular markers. Three months after surgery, metastasis to the bone and lymph nodes was observed, and the patient died of the disease shortly thereafter.

Discussion

Epithelioid angiosarcoma of bone is characterized by an aggressive clinical course. A possibility of epithelioid angiosarcoma of bone should be considered in cases with such epithelial features, particularly if only small specimens are available.

Epithelioid hemangioendothelioma of the spine: results at seven years of average follow-up in a series of 10 cases surgically treated and a review of literature

PURPOSE

To review a series of ten cases with epithelioid hemangioendothelioma of the spine, that have undergone surgery to describe clinical presentation, results and complications associated with surgical treatment; a review of literature reporting the main characteristics of the cases already published has been reported.

METHODS

A review of patients affected by epithelioid hemangioendothelioma surgically treated by the senior author from 1995 to 2012 was carried out. Ten cases were identified and clinical and radiological characteristics, therapy, complications and survival were valued.

RESULTS

Wide margin was achieved in two out of ten cases, marginal margin in seven and intralesional margin in one case. Average intraoperative blood loss was about 2,800 ml. Reported complications were one case of cord injury, one of dural tear, two cases of massive blood loss, a case of reconstruction failure, a wound dehiscence with deep infection, a pneumonia episode and a deep vein thrombosis with pulmonary embolism. Average follow-up was 84.4 months. Two local recurrences, after 32 and 37 months and two deaths for metastasis, after 14 and 36 months, were reported. Although several chemotherapy protocols are available for the treatment of EH of soft tissue, they are not relevant for the bone.

CONCLUSIONS

Wide surgery is probably associated with a better prognosis. Indeed most deaths and local recurrences reported in literature happened after intralesional surgery or chemotherapy/RT alone. The presenting study suggests that the best approach to achieve long-term local control and a major survival could be wide surgery, nevertheless more cases series are necessary to verify survival rate.

Vascular bone tumors: a proposal of a classification based on clinicopathological, radiographic and genetic features

The classification of vascular bone tumors remains challenging, with considerable morphological overlap spanning across benign to malignant categories. The vast majority of both benign and malignant vascular tumors are readily diagnosed based on their characteristic histological features, such as the formation of vascular spaces and the expression of endothelial markers. However, some vascular tumors have atypical histological features, such as a solid growth pattern, epithelioid change, or spindle cell morphology, which complicates their diagnosis. Pathologically, these tumors are remarkably similar, which makes differentiating them from each other very difficult. For this rare subset of vascular bone tumors, there remains considerable controversy with regard to the terminology and the classification that should be used. Moreover, one of the most confusing issues related to vascular bone tumors is the myriad of names that are used to describe them. Because the clinical behavior and, consequently, treatment and prognosis of vascular bone tumors can vary significantly, it is important to effectively and accurately distinguish them from each other. Upon review of the nomenclature and the characteristic clinicopathological, radiographic and genetic features of vascular bone tumors, we propose a classification scheme that includes hemangioma, hemangioendothelioma, angiosarcoma, and their epithelioid variants.

Monoclonality of multifocal epithelioid hemangioendothelioma of the liver by analysis of WWTR1-CAMTA1 breakpoints

Similar to other vascular tumors, epithelioid hemangioendothelioma (EHE) can have multifocal presentation in up to 50% of cases. However, whether multifocal EHE represents an unusual pattern of metastasis or multiple separate primary tumors remains to be elucidated. Our recent identification of a WWTR1-CAMTA1 fusion as the genetic hallmark of EHE irrespective of anatomic location was used to clarify this question by comparing the similarity of translocation breakpoints. In our previous study, we found variability of the fusion transcripts of the t(1;3)(p36;q25) translocation among different patients with EHE. Thus, we undertook a molecular analysis of six samples from two patients with multicentric hepatic EHE to test our hypothesis that the presence of identical breakpoints in WWTR1 and CAMTA1 support the monoclonal nature of multifocal EHE. Using reverse transcription-polymerase chain reaction (RT-PCR) and subsequent sequencing, we confirmed an identical WWTR1-CAMTA1 fusion transcript product from different nodules in each patient. Our results confirm that multifocal EHE are monoclonal and thus represent metastatic implants of the same neoplastic clone rather than a "field-effect" or synchronous occurrence of multiple neoplastic clones.

Epithelioid hemangioma of bone and soft tissue: a reappraisal of a controversial entity

BACKGROUND

The controversy surrounding diagnosis of an epithelioid hemangioma (EH), particularly when arising in skeletal locations, stems not only from its overlapping features with other malignant vascular neoplasms, but also from its somewhat aggressive clinical characteristics, including multifocal presentation and occasional lymph node involvement. Specifically, the distinction from epithelioid hemangioendothelioma (EHE) has been controversial. The recurrent t(1;3)(p36;q25) chromosomal translocation, resulting in WWTR1-CAMTA1 fusion, recently identified in EHE of various anatomic sites, but not in EH or other epithelioid vascular neoplasms, suggests distinct pathogeneses.

QUESTION/PURPOSES

We investigated the clinicopathologic and radiologic characteristics of bone and soft tissue EHs in patients treated at our institution with available tissue for molecular testing.

PATIENTS AND METHODS

Seventeen patients were selected after confirming the pathologic diagnosis and fluorescence in situ hybridization analysis for the WWTR1 and/or CAMTA1 rearrangements. Four patients had multifocal presentation. Most patients with EH of bone were treated by intralesional curettage. None of the patients died of disease and only four patients had a local recurrence.

RESULTS

Our results, using molecular testing to support the pathologic diagnosis of EH, reinforce prior data that EH is a benign lesion characterized by an indolent clinical course with an occasional multifocal presentation and rare metastatic potential to locoregional lymph nodes.

CONCLUSION

These findings highlight the importance of distinguishing EH from other malignant epithelioid vascular tumors as a result of differences in their management and clinical outcome.

LEVEL OF EVIDENCE

Level IV, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Osteosarcoma: Differential Diagnostic Considerations

Accurate diagnosis of bone-forming tumors, including correct subclassification of osteogenic sarcoma is critical for determination of appropriate clinical management and prediction of patient outcome. The morphologic spectrum of osteogenic sarcoma is extensive, however, and its histologic mimics are numerous. This review focuses on the major differential diagnoses of the specific subtypes of osteosarcoma, presents summaries of various diagnoses, and provides tips to overcoming pitfalls in diagnosis.

Progression of aggressive metastatic carcinosarcoma after treatment of epithelioid osteosarcoma

Osteosarcoma is the most common primary malignant osseous neoplasm, constituting approximately 35% of skeletal malignancies. The different subtypes of osteosarcoma are differentiated based on clinical, histologic, and radiographic data, as well as the variable amount of osteoid produced by malignant cells. The epithelioid osteosarcoma subtype accounts for only 5.7% of all osteosarcomas and portends an extremely poor prognosis. The 5-year survival rate for patients with epithelioid osteosarcoma treated with surgery (with or without chemotherapy) is 13.5%. This is in direct contrast to the >70% ten-year survival rate of conventional osteosarcoma treated with surgery and chemotherapy. This article presents a fatal case of epithelioid osteosarcoma in an 11-year-old girl with right knee pain of 6 months' duration. Biopsy demonstrated morphologic findings consistent with high-grade osteosarcoma with epithelioid features. The epithelioid component was positive for vimentin and CD99; however, fluorescent in situ hybridization for the (11;22) translocation was negative. In this case, the epithelioid cells failed to respond to conventional or subsequent experimental chemotherapy for osteosarcoma and eventual metastasized to the lymph nodes and lungs despite multiple ablative surgeries. This case report supports the concept of carcinosarcoma with malignant cells lines arising from 2 different cellular lineages or a common cellular precursor. The epithelial component was more aggressive than the cells of mesenchymal origin, highlighting the need for continued research and a more favorable outcome for this rare subset of osteosarcoma.

Epithelioid osteosarcoma of the jaw

Epithelioid osteosarcoma (OS) is a rare sub-type of OS with an aggressive behavior. An epithelioid OS was diagnosed in an 8-year-old female with painful swelling of the left jaw. After two courses of chemotherapy (cisplatin/methotrexate/doxorubicin), the patient presented a progressive disease. After hemimandibulectomy, 13 courses of post-operative chemotherapy (cisplatin/methotrexate/doxorubicin/ifosfamide) were performed. Histological and ultra-structural examination showed a high grade neoplasm consisting of sheets of epithelioid cells with focal osteoid formation. The patient is alive and in complete remission 42 months from diagnosis.

Epithelioid osteosarcoma of the mandible: a rare case with unusual immunoprofile

A 42-year-old woman presented a large, nontender, quickly progressive mass in the left mandible. Radiograph showed extensive destruction of the angle, posterior body, and ramus of the left side of the mandible. The patient was surgically treated by hemimandibulectomy. Microscopically, the tumor was composed of large epithelioid cells, many of them showing polarized nuclei, and evident eosinophilic cytoplasm. The predominant pattern was trabecular, and rosette-like structures were also observed. Typical osteoid-containing cells surrounded by malignant cells were found in a few areas. Immunohistochemistry for a large panel of antibodies showed positivity for osteocalcin, osteonectin, osteopontin, VS38c, and S-100. CD34 saliented the hemangiopericytoma-like distribution of the blood vessels. Collagen I was focally positive for the extracellular matrix and malignant osteoid. All other markers were negative, including vimentin and cytokeratins. To the best of our knowledge, this is the first case of epithelioid osteosarcoma affecting the mandible and the second case affecting the jaws that has been reported in the literature.

Epithelial--mesenchymal and mesenchymal--epithelial transitions in carcinoma progression

Like a set of bookends, cellular, molecular, and genetic changes of the beginnings of life mirror those of one of the most common cause of death--metastatic cancer. Epithelial to mesenchymal transition (EMT) is an important change in cell phenotype which allows the escape of epithelial cells from the structural constraints imposed by tissue architecture, and was first recognized by Elizabeth Hay in the early to mid 1980's to be a central process in early embryonic morphogenesis. Reversals of these changes, termed mesenchymal to epithelial transitions (METs), also occur and are important in tissue construction in normal development. Over the last decade, evidence has mounted for EMT as the means through which solid tissue epithelial cancers invade and metastasize. However, demonstrating this potentially rapid and transient process in vivo has proven difficult and data connecting the relevance of this process to tumor progression is still somewhat limited and controversial. Evidence for an important role of MET in the development of clinically overt metastases is starting to accumulate, and model systems have been developed. This review details recent advances in the knowledge of EMT as it occurs in breast development and carcinoma and prostate cancer progression, and highlights the role that MET plays in cancer metastasis. Finally, perspectives from a clinical and translational viewpoint are discussed.