Dedifferentiated parosteal osteosarcoma: The experience of the Rizzoli Institute

Effect of adjuvant chemotherapy on localized dedifferentiated low-grade osteosarcoma: a systematic review

PURPOSE

Dedifferentiated low-grade osteosarcomas, which are considered high grade malignancies, can arise from the dedifferentiation of parosteal and low-grade osteosarcomas. Usually, localized dedifferentiated low-grade osteosarcomas are treated by wide resection, and the efficacy of adjuvant chemotherapy is controversial. We conducted a systematic review of studies that investigated the rates of mortality and significant events, such as recurrence and metastases, in localized dedifferentiated low-grade osteosarcoma patients who received wide resection only and in those who received wide resection and (neo-)adjuvant chemotherapy.

METHODS

We identified 712 studies through systematic searches of Embase, PubMed, and the Cochrane Central Register of Controlled Trials databases. Of those studies, seven were included in this review and none were randomized controlled trials. In the seven studies, 114 localized dedifferentiated low-grade osteosarcoma patients were examined.

RESULTS

Mortality rates of the resection plus chemotherapy (R + C) and the resection only (Ronly) groups were 20.3% and 11.4%, respectively [overall pooled odds ratio, 1.59 (P = 0.662); heterogeneity I2, 0%]. The local recurrence or distant metastasis rate in the R + C group was 36.7% and that in the Ronly group was 28.6% [overall pooled odds ratio, 1.37 (P = 0.484); heterogeneity I2 was 0%].

CONCLUSIONS

Results show a limited efficacy of adjuvant chemotherapy for localized dedifferentiated low-grade osteosarcoma. However, because this was a systematic review of retrospective studies that examined a small number of patients, future randomized controlled trials are needed.

A Successful Clinical Outcome 29 Months Following Improper Placement of the Compress Implant: A Case Report

CASE

A 24-year-old woman presented with dedifferentiated parosteal osteosarcoma of the proximal femur and was treated with limb salvage surgery using the Compress implant. It was implanted with a technical error, was not revised, and has demonstrated no negative outcomes 29 months postoperatively.

CONCLUSION

An instance of incorrect pin placement during the implantation of a Zimmer Compress implant is presented with good survivorship. This report acts as information for other surgeons who might inadvertently obtain unicortical fixation. In this patient, revision surgery was avoided and an excellent, short-term outcome was achieved while avoiding the potentially devastating complications associated with revision implantation.

Limb Salvage Surgery in a Rare Case of Recurrent Parosteal Osteosarcoma with Vascular Graft Thrombosis

Recurrent parosteal sarcomas with vascular involvement are rare and present unique challenges in their diagnosis and management. We report the case of a 21-year-old woman with parosteal osteosarcoma of the left distal femur, encasing the popliteal vessels. En bloc transarticular resection of the distal femur and popliteal vessels was performed, followed by reconstruction using a modular prosthesis and a saphenous vein autograft for both the artery and vein. On the 1st postoperative day, the patient developed an arterial thrombus requiring reintervention with a jump polytetrafluoroethylene (PTFE) graft. Histopathology confirmed parosteal osteosarcoma. After a disease-free survival of 41 months, the patient experienced local recurrence involving the PTFE graft, leading to graft compression, erosion, and subsequent thrombosis. Despite these complications, limb salvage was possible due to adequate collateral blood supply. This case highlights the feasibility of limb salvage surgery in select cases of parosteal osteosarcoma with vascular involvement.

Current topics and management of head and neck sarcomas

Given the low incidence, variety of histological types, and heterogeneous biological features of head and neck sarcomas, there is limited high-quality evidence available to head and neck oncologists. For resectable sarcomas, surgical resection followed by radiotherapy is the principle of local treatment, and perioperative chemotherapy is considered for chemotherapy-sensitive sarcomas. They often originate in anatomical border areas such as the skull base and mediastinum, and they require a multidisciplinary treatment approach considering functional and cosmetic impairment. Moreover, head and neck sarcomas may exhibit different behaviour and characteristics than sarcomas of other areas. In recent years, the molecular biological features of sarcomas have been used for the pathological diagnosis and development of novel agents. This review describes the historical background and recent topics that head and neck oncologists should know about this rare tumour from the following five perspectives: (i) epidemiology and general characteristics of head and neck sarcomas; (ii) changes in histopathological diagnosis in the genomic era; (iii) current standard treatment by histological type and clinical questions specific to head and neck; (iv) new drugs for advanced and metastatic soft tissue sarcomas; and (v) proton and carbon ion radiotherapy for head and neck sarcomas.

Parosteal Osteosarcoma of the skull: Pathophysiological and imaging review

Parosteal Osteosarcoma (POS) is a well-differentiated low-grade malignant sarcoma occurring at the bone surface. POS of the skull is exceedingly rare, with only 4 temporal bone cases reported in modern literature. This tumor may resemble a multitude of entities, hence identifying it is critical. This may be achieved through a combination of clinical, histopathological, and imaging diagnostic techniques. POS may recur locally or dedifferentiate, the latter having a worse prognosis. This review aims to update the reader regarding the management of the rare Parosteal Osteosarcoma located in the skull bone.

Osteogenic sarcomas of the hands: A case series with emphasis in its peculiarities and literature review

AIM

To present our experience on osteosarcomas of the hands and review the existing literature pertaining osteosarcomas in this extremely rare location.

METHODS

and results: Seven cases of osteosarcomas of the hands were reviewed, and a literature search of all primary osteosarcomas of the hands was performed. All tumors occurred in adults (mean age, 41 years) and were located mainly around the metacarpophalangeal joints. All patients presented with localized long-lasting pain as main symptom. The mean size at diagnosis was 33 mm. Three tumors were low-grade central osteosarcomas, 1 low-grade central chondroblastoma-like osteosarcoma and 3 high-grade osteosarcomas. All tumors were positive for mouse double-minute 2 homolog (MDM2) immunohistochemistry. Three cases yielded results with fluorescence in-situ amplification for MDM2 (12q15)/CEP12. At last follow-up, one patient with a high-grade osteosarcoma was dead of disease. The literature review revealed similar demographic and site distribution of osteosarcomas within the hands than our series and an unusually high proportion of low-grade central and parosteal osteosarcomas when compared to the proportion of these infrequent neoplasms in the whole skeleton.

CONCLUSIONS

osteosarcomas of hands present in older individuals compared to the population affected by conventional osteosarcomas of all sites. Importantly from a diagnostic, therapeutic and prognostic points of view, around 40% of osteosarcomas of the hands are low-grade osteosarcomas of the central or parosteal types.

Dedifferentiated Low-Grade Osteosarcoma, Outcome with or Without Chemotherapy: A Systematic Review

The treatment of low-grade osteosarcomas is surgical resection with wide margins. In instances of dedifferentiation, a therapeutic paradigm similar to that of conventional high-grade osteosarcoma has not been adequately evaluated in these neoplasms. The main objective of this review was to define whether the addition of chemotherapy to surgical treatment has an impact on the survival of patients with dedifferentiated low-grade osteosarcomas. Secondary objectives were to observe the degree of histological response to neoadjuvant chemotherapy and to describe the percentage of de novo dedifferentiation. A systematic search of articles including dedifferentiated low-grade osteosarcomas, published between 1980 and 2022 was carried out in the PubMed, Cochrane and Scielo databases. A qualitative synthesis of the results was performed. Twenty-three articles comprising 117 patients were included. The survival of patients treated with surgery alone and surgery with chemotherapy was not statistically significant between the two groups. A good histological response was seen in 20% of specimens treated with neoadjuvant chemotherapy. De novo dedifferentiation was seen in approximately a fifth of low-grade osteosarcomas. The evidence available suggests that the addition of chemotherapy does not have an impact on the survival of patients with low-grade dedifferentiated osteosarcomas.

Timing of treatment in osteosarcoma: challenges and perspectives - a scoping review

BACKGROUND

The timing of events in the management of osteosarcoma may be critical for patient survivorship; however, the prognostic value of factors such as onset of symptoms or initiation of therapy in these patients has not been studied. This study sought to review the literature reporting treatment of osteosarcoma to determine the utility of event timing as a prognostic indicator. Due to significant heterogeneity in the literature, this study was conducted as a scoping review to assess the current state of the literature, identify strengths and weaknesses in current reporting practices, and to propose avenues for future improvement.

MAIN BODY

This review screened 312 peer-reviewed studies of osteosarcoma in any anatomic location published in an English journal for reporting of an event timing metric of any kind in a population of 6 or more. Thirty-seven studies met inclusion/exclusion criteria and were assessed for level of evidence, quality, and event timing metric. Reviewers also collated: publication year, population size, population age, tumor site, tumor type, surgical treatment, and adjuvant medical treatment. Extracted event timing data were further characterized using nine standardized categories to enable systematic analysis. The reporting of event timing in the treatment of osteosarcoma was incomplete and heterogenous. Only 37 of 312 (11.9%) screened studies reported event timing in any capacity. The period between patient-reported symptom initiation and definitive diagnosis was the most reported (17/37, 45.9%). Symptom duration was the second most reported period (10/37, 27.0%). Event timing was typically reported incidentally and was never rigorously incorporated into data analysis or discussion. No studies considered the impact of event timing on a primary outcome. The six largest studies were assessed in detail to identify pearls for future researchers. Notable shortcomings included the inadequate reporting of the definition of an event timing period and the pooling of patients into poorly defined timing groups.

CONCLUSIONS

Inconsistent reporting of event timing in osteosarcoma treatment prevents the development of clinically useful conclusions despite evidence to suggest event timing is a useful prognostic indicator. Consensus guidelines are necessary to improve uniformity and utility in the reporting of event timing.

Dedifferentiation in low-grade osteosarcoma: a Japanese Musculoskeletal Oncology Group (JMOG) study

BACKGROUND

Low-grade osteosarcomas, namely parosteal osteosarcoma (POS) and low-grade central osteosarcoma (LGCOS), occasionally dedifferentiate into high-grade malignancy, referred to as dedifferentiation in low-grade osteosarcoma (DLOS). This study aimed to elucidate the clinicopathologic features of DLOS, which are poorly described to date due to the extreme rarity of the disease.

METHODS

A total of 33 patients with DLOS were included. Clinical characteristics, including the diagnostic accuracy of tumor biopsy, multimodal treatments, and clinical course, were retrospectively reviewed. Univariate analysis was performed to identify prognostic factors associated with overall survival (OS) and metastasis-free survival (MFS).

RESULTS

The tumor subtypes comprised 10 cases (30.3%) of LGCOS and 23 cases (69.7%) of POS. The timing of dedifferentiation was synchronous in 25 (75.8%) and metachronous in 8 (24.2%) patients. The rates of preoperative diagnosis of DLOS were 40.0% and 65.4% for core needle biopsy and incisional biopsy, respectively. All patients underwent surgery and 25 patients received perioperative chemotherapy. Of the 13 patients who received neoadjuvant chemotherapy, 11 exhibited a poor histological response. The 5-year OS and MFS rates were 88.1% and 77.7%, respectively. Univariate analysis revealed that local recurrence was associated with poor OS (P < 0.01) and MFS (P < 0.01). Perioperative chemotherapy did not affect OS or MFS.

CONCLUSIONS

The diagnostic accuracy of tumor biopsy for DLOS was lower than that for bone sarcomas, as reported previously. In contrast to conventional osteosarcomas with high chemosensitivity, both histological responses and survival analysis revealed low efficacy of chemotherapy for DLOS.

Role of MDM2, CDK4, BCL2, Parafibromin and Galectin 1 in Differentiating Osteosarcoma from its Benign Fibro-osseous Lesions

Benign fibro-osseous lesions (BFOLs) are a diverse group of lesions showing considerable degree of overlap with low grade osteosarcoma (LGOS). Further, de-differentiated osteosarcoma (DOS) is usually indistinguishable from conventional high-grade OS (COS) if LGOS foci are not identified. Thus, there is a need for adjunctive immunohistochemical markers to differentiate OS from benign FOLs as well as DOS from COS. This study evaluated the role of immunohistochemical expression of MDM2, CDK4, parafibromin, BCL-2 and Galectin-1 (Gal-1) in accurate characterization of benign FOLs and in differentiating them from OS. From our archives, we retrieved 101 tissue samples which were diagnosed as osteosarcoma (OS) /ossifying fibroma (OF) / fibrous dysplasia (FD) or fibrous hyperplasia (FH) and examined their immunohistochemical staining pattern with the aforementioned antibodies. MDM2 showed 100% specificity for diagnosing OS. CDK4 and Gal-1 showed linear increase in immunoexpression from benign BFOLs to OS. BCL-2 showed equivocal immunopositivity in OF and OS, but the positivity was higher than that observed in FD. The highest immunoexpression for parafibromin was seen in FD followed by OF and OS cases. Thus, MDM2 is most specific, and Gal-1 is most sensitive of all the markers studied in differentiating OS from benign mimics. Combination of these two markers can be used as an adjunct to conventional imaging and microscopy in accurate characterization of these lesions. Further MDM2 overexpression can differentiate DOS and COS.

JUXTACORTICAL OSTEOSARCOMA: CLINICAL EVOLUTION AND DEDIFFERENTIATION RELATED FACTORS

ABSTRACT Objective: Evaluate risk factors related to clinical evolution and dedifferentiation of parosteal (juxtacortical) osteosarcoma to high-grade osteosarcoma. Methods: Retrospective cohort study performed over a period of 25 years, using data from medical records of patients diagnosed with parosteal osteosarcoma. The data were submitted to statistical analysis by Fisher’s exact test and Student’s t-test. Results: Of the 326 patients treated for osteosarcoma, we identified 17 patients diagnosed with parosteal osteosarcoma. Of these, 4 (23.5%) were not actually diagnosed with parosteal osteosarcoma and 4 did not have the minimum data required for analysis, being excluded from the study. Of the 9 patients studied, we observed that 3 (33.3%) evolved with tumor dedifferentiation to high-grade osteosarcoma. Moreover, 2 (66.7%) had local recurrence and 2 (66.7%) metastases. Conclusion: Age, sex, and the tumor size were not directly related to the dedifferentiation from parosteal osteosarcoma to high-grade osteosarcoma. The most aggressive clinical evolution - presence of local recurrences and metastasis - in parosteal osteosarcoma occurred in tumors with dedifferentiation, however, we cannot associate each other as cause and effect, but as related factors. Level of Evidence IV, Case Series.

Surface bone sarcomas: an update on current clinicopathological diagnosis and treatment

Surface bone sarcomas are rare malignant bone tumours. Osseous and cartilaginous surface bone sarcomas are the most common, with parosteal and periosteal osteosarcomas, periosteal chondrosarcomas and secondary peripheral chondrosarcomas being the most frequent.

Their clinical symptoms are non-specific and include pain for several months, swelling and limited range of motion of the adjacent joints.

Prompt diagnosis is important, as biological behaviour, imaging and histopathologic characteristics, treatment and prognosis differ considerably from their conventional intramedullary counterparts. Moreover, their imaging characteristics are not infrequently non-characteristic and may be misinterpreted as juxtacortical benign lesions leading to incorrect diagnosis and treatment, with life-threatening repercussions. Molecular studies and histopathological sampling are essential for accurate diagnosis.

There are still numerous issues regarding the biology, pathophysiology and treatment options of these entities due to their rarity.

Cite this article: EFORT Open Rev 2021;6:905-917. DOI: 10.1302/2058-5241.6.210064

Case Report: Metastatic Parosteal Osteosarcoma in a Dog

This case report describes a rare form of malignant bone tumor in an 8-year-old Labrador retriever. This dog initially presented for evaluation of a right distal humeral mass. Radiographs of the right elbow and thorax were performed, revealing a smooth mineralized mass adjacent to the lateral aspect of the distal humerus and a 5mm pulmonary nodule. Computed tomography (CT) of the humerus and thorax showed a smooth mineralized lesion adjacent to the lateral humeral epicondyle, and a right cranial lung lobe nodule with a thin mineral rim. Surgical biopsies of both lesions were diagnostic for parosteal osteosarcoma (POSA). The dog was then treated with stereotactic body radiation therapy (SBRT) which controlled the dog's discomfort for 14 months until he became progressively painful and subsequently had his right forelimb amputated. This case report is the first to document the CT imaging characteristics of a metastatic appendicular POSA in a dog and the first dog described with POSA treated with SBRT. The dog lived for 623 days after histopathologic diagnosis and 849 days after initial presentation with pulmonary metastatic disease.

Pathology of pleomorphic/undifferentiated and dedifferentiated bone neoplasms

Primary malignant bone tumors are uncommon and their accurate classification requires careful correlation of clinical, radiological, and pathologic findings. It is a heterogeneous group of tumors with a wide spectrum of morphology and their biological potential can be of low- or high-grade, depending on their risk for developing metastases. Over the past several decades, the classification of bone sarcomas has remained largely constant. However, some of the tumors have been reclassified and several new entities have emerged. In this review, we will focus on pleomorphic fibrosarcoma/UPS and dedifferentiated bone tumors, discuss their key diagnostic features, differential diagnosis, and their relation to prognosis.

Co-occurrence of malignant neoplasm and Hyperostosis Frontalis Interna in an Iron Age individual from Münsingen-Rain (Switzerland): A multi-diagnostic study

OBJECTIVE

To re-analyze one of the oldest cases of malignant bone neoplasm with different analytical techniques.

MATERIAL

The available skeletal remains of grave 138 (G138) from the Iron Age necropolis of Münsingen-Rain (Switzerland, 420-240 BC).

METHODS

The bones are analyzed by means of morphological, radiographic, histological, and biogeochemical methods.

RESULTS

The individual, a male aged between 35-50 years old, presents morphologically and radiographically a previously described coral-like bone neoformation on the proximal left humerus. The new analyses highlight previously undocumented coarse bone proliferation on the left scapula and lobular apposition on the endocranial surface of the frontal bone. The histological analysis of the humerus shows a 'lace-like' pattern of osteoid deposition without lamellation.

CONCLUSIONS

Our data support a diagnosis of osteoblastic malignant neoplasm, probably an osteosarcoma or, more likely, a dedifferentiated chondrosarcoma for the humerus and scapula, and of hyperostosis frontalis interna on the frontal. The co-presence of a malignant neoplasm and hyperostosis frontalis interna may be related to a hormonal imbalance, a possibility also suggested by atypical funerary treatment.

SIGNIFICANCE

This study confirms G138 as one of the oldest cases of malignant bone neoplasm, adds new paleopathological data on this individual, and demonstrates the advantages of a multidisciplinary approach.

LIMITATIONS

The discussion of the pathological changes is limited by the representation and preservation of the skeletal elements.

SUGGESTION FOR FUTURE RESEARCH

Biomolecular and protein biomarkers analyses may help to refine the diagnostic conclusions.

The value of chest and skeletal staging in parosteal osteosarcoma: two-centre experience and literature review

OBJECTIVE

To determine the value of chest and skeletal staging in patients with parosteal osteosarcoma (POS), and the incidence of late local and chest recurrence.

MATERIALS AND METHODS

Retrospective review of patients across two institutions with histological confirmation of POS diagnosed between January 2007 and March 2020. Data collected included age, sex, skeletal location, results of chest CT and whole-body bone scintigraphy (WB-BSc) or whole-body MRI (WB-MRI) obtained at initial diagnosis. The histological tumour grade based on surgical resection specimens was classified as low-grade POS (LG-POS) and dedifferentiated POS (DD-POS). Findings of chest CT and skeletal staging were correlated with tumour grade. Follow-up chest CT and MRI studies were reviewed to determine the rate of late lung metastases and local recurrence.

RESULTS

There were 27 males and 44 females, mean age 33 years (range 12-79 years). The femur (n = 43) and tibia (n = 14) were the most commonly involved bones. From surgical resection histology, 42 (59.2%) were LG-POS and 29 (40.8%) were DD-POS. WB-BSc/WB-MRI showed no skeletal metastases, while 1 case of DD-POS presented with bilateral calcified lung metastases. At follow-up, 7 patients (9.9%) developed lung metastases (mean of 18.9 months, range 10-48 months) from initial presentation, of which all were DD-POS. All but 1 patient who developed subsequent lung metastases had a local recurrence.

CONCLUSIONS

Skeletal staging is unlikely to be of value in POS. Staging chest CT is very unlikely to demonstrate lung metastases in LG-POS and could be limited to DD-POS, particularly at the time of local recurrence.

Parosteal osteosarcoma associated with a low-grade component mimicking well-differentiated liposarcoma: a case report

Parosteal osteosarcomas and well-differentiated liposarcomas are both well-differentiated locally aggressive tumors. They both have simple karyotypes with amplification of the 12q13-15 regions including MDM2 and CDK4 genes. In this report, we describe the case of a parosteal osteosarcoma intertwined with a low-grade component similar to a well-differentiated liposarcoma. The association of a bone component with an adipose component was initially overlooked. We describe the histological, imaging, and molecular characteristics of this tumor stressing the importance of radio-pathological correlation. To our knowledge, this is the second report of a parosteal osteoliposarcoma. Awareness of this rare presentation may allow radiologists and surgeons to recognize the peripheral fatty component as an integral part of the tumor.

A review of imaging of surface sarcomas of bone

Surface lesions of bone are uncommon. Although their imaging features generally mirror those of their intramedullary counterparts, surface lesions may demonstrate distinct characteristics which along with their unusual location present a diagnostic challenge. Surface sarcomas are usually of a lower grade compared with intramedullary variants, leading to differences in management. Osteosarcoma arising from the cortical surface of the bone is termed juxtacortical or surface osteosarcoma and includes three distinct entities: parosteal, periosteal, and high-grade surface osteosarcoma. We also review the features intracortical osteosarcoma, which some authors include under the umbrella term surface osteosarcoma. These lesions exhibit biologic features distinct from those of conventional intramedullary osteosarcoma, which underlines the importance of accurate imaging diagnosis. Periosteal chondrosarcoma and periosteal Ewing sarcoma also have distinctive imaging appearances. The purpose of this article is to review surface sarcomas of bone with regard to their clinical and radiological features and to discuss the differential diagnosis for each condition.

Inflammation and infiltration: can the radiologist draw a line? MRI versus CT to accurately assess medullary involvement in parosteal osteosarcoma

Cancer causes inflammation as it progresses through healthy tissue. The differentiation of tumoral growth from the surrounding inflammatory change is paramount in planning surgeries seeking to preserve function. This retrospective study aims at illustrating how a careful use of imaging (computed tomography (CT)/magnetic resonance imaging (MRI)) can help to draw the line between infiltration and inflammation. Out of 72 cases of parosteal osteosarcoma in our institution we selected 22 which had pretreatment imaging, and out of those, 14 that had both MRI and CT. Using Fisher's exact test, we evaluated the performance of each technique on accurately diagnosing medullary tumor infiltration, using histological analysis as a gold standard. All cases (14/14) demonstrated medullary abnormality on MRI, but only 6/14 (42.9%) demonstrated abnormality on CT. The 8/14 cases with MRI abnormality but no CT abnormality (57.1%) showed inflammation with no tumoral cells present on histological analysis. In the cases where the two examinations showed medullary abnormality (6/14) histology demonstrated tumoral infiltration. MRI demonstrated high sensitivity and negative predictive value, but low specificity and low positive predictive value and accuracy (P=1). CT demonstrated high sensitivity, specificity, high positive and negative predictive values and accuracy (P = 0.000333). MRI is highly sensitive for the detection of medullary abnormality but lacks specificity for tumor invasion. Correlation with CT is recommended in all cases of positive MR to add specificity for tumors. The adequate use of the two imaging methods allows to differentiate between inflammatory change and tumoral infiltration in POS, relevant for surgical planning.

Parosteal Osteosarcoma: A Benign-Looking Tumour, Amenable to a Variety of Surgical Reconstruction

Osteosarcoma arising from cortical surface is classified into parosteal, periosteal and high-grade surface osteosarcoma. Along the spectrum, parosteal osteosarcoma occupies the well-differentiated end. It is a relatively rare disease entity, comprised only 4% of all osteosarcomas and barely reported in the literature. The objective of this study is to describe cases of parosteal osteosarcoma as well as a variety of treatment options amenable to such entity. Six cases of parosteal osteosarcoma were identified based on histopathological reports in a tertiary referral hospital in Jakarta, Indonesia between January 2001 and December 2019. The mean age was 29.8 years old; four of them (66.7%) were male. Distal end of femur was the most commonly involved bone (five cases, 83.3%). The patients were treated with wide excision followed by several different reconstruction methods: replacement with endoprosthesis, extracorporeal irradiation, knee arthrodesis, or prophylactic fixation. One of our patients presented with dedifferentiated component, and therefore was treated by limb ablation. While two cases died of pulmonary metastasis, other patients reported fair to excellent functional outcome.

[Osteoid-forming bone tumors : Morphology and current translational cell biology]

Osteoid osteoma and osteoblastoma are the most important benign osteoid-forming tumors. They grow slowly and are well differentiated. Histologically, the tumor cells show no atypia and no increased mitoses. In typical cases, they can be clearly diagnosed. However, the rare cases on the dividing line between osteoblastoma and osteosarcoma are extremely problematic. In these cases, molecular genetic investigations should contribute to finding the correct diagnosis in the future.Juvenile highly malignant osteosarcoma is the most important malignant osteoid-forming tumor. About 40 years ago, neoadjuvant chemotherapy was introduced for the mostly young patients. This therapy highly significantly improved prognosis. However, a plateau phase was quickly reached and the last several decades have seen no further progress in conventional therapeutic approaches. There is no doubt that further progress can only be achieved on the basis of new molecular genetic and cell biological findings. The target-therapeutic strategies derived from these findings will be discussed in this review.The rare parosteal osteosarcoma and the even rarer periosteal osteosarcoma are mostly not highly malignant tumors that are located on the surface of bone. The parosteal osteosarcoma is usually G1 and the periosteal osteosarcoma G2. Occasionally, the differential diagnosis between a parosteal osteosarcoma and a fibrous dysplasia is difficult. In such rare cases, the detection of GNAS mutations in fibrous dysplasia can prove useful. In contrast to chondromas and chondrosarcomas, periosteal osteosarcomas do not contain IDH1 and IDH2 mutations.

[Biphasic (dedifferentiated) osteosarcoma of the lung in the light of current ideas on biphasic tumors]

The paper presents a case of biphasic (dedifferentiated) osteosarcoma arising primarily on the lung, which has not previously encountered in the literature. It provides a detailed description of its clinical, instrumental, and morphological pattern. It also analyzes the literature on the study of primary pulmonary osteosarcoma and extraskeletal osteosarcoma with high-grade transformation. This clinical case is a clear example of classic biphasic sarcoma interpreted in the context of the phenomenon of biphasic tumors. Their most important aspects (terminology, morphology, biological behavior, and a mechanism of dedifferentiation) are highlighted; the key characteristics of biphasic sarcomas are listed.

[Parosteal low-grade osteosarcoma with focal differentiation]

This case study deals with the case of a 16-year-old male patient with a low-grade parosteal osteosarcoma of the distal femur with focal differentiation. Case history, disease course, and surgery as well as the pathological workup with final diagnosis are presented. Relevant radiologic and pathologic differential diagnoses und diagnostic pitfalls are explained in detail and discussed. Additionally, postoperative treatment options are illustrated.

Gene amplification and tumor grading in parosteal osteosarcoma

BACKGROUND

Parosteal osteosarcoma (POS) is a unique low grade osteosarcoma. Two separate oncogenes, MDM2 and CDK4, are specifically amplified in POS. Its clinical behavior is usually indolent. In some occasions, it may progress to high grade and become fatal. Malignant transformation with high grade differentiation is the most reliable indicator to predict its aggressiveness and metastatic potential. This study is to discover the relationship between gene amplification and grading.

METHODS

Retrospective analysis of MDM2/CDK4 expression/amplification using immunostaining, multiplex quantitative polymerase chain reaction (MQPCR) and fluorescence in situ hybridization (FISH) were studied on 14 patients with recurrent POS.

RESULTS

Forty tumor specimens in formalin-fixed paraffin-embedded blocks from 14 patients of POS were included in this study. Twenty-seven tumors are low-grade, 13 are high-grade. All POS showed increased expression of both MDM2 and CDK4 proteins, but not those from conventional osteosarcoma. Except some tumors were non-informative (poor DNA quality), the rest of POS had a marked increase of MDM2 and CDK4 genes copies by MQPCR, and confirmed by MDM2 FISH. Moreover, the folds of amplification increase as tumors progress. And, the amplification folds in high-grade POS are consistently higher than those of conventional ones.

CONCLUSION

FISH and MQPCR are both useful assays for estimating oncogene amplification status in bone tumors. Amplification levels of MDM2 and CDK4 are related to tumor grading and progression. Molecular determination of gene amplification status can be a reliable alternative for predicting clinical behavior of POS at small biopsies.

A clinical comparison between dedifferentiated low-grade osteosarcoma and conventional osteosarcoma

AIMS

The purpose of this study was to clarify the clinical behaviour, prognosis, and optimum treatment of dedifferentiated low-grade osteosarcoma (DLOS) diagnosed based on molecular pathology.

PATIENTS AND METHODS

We retrospectively reviewed 13 DLOS patients (six men, seven women; median age 32 years (interquartile range (IQR) 27 to 38)) diagnosed using the following criteria: the histological coexistence of low-grade and high-grade osteosarcoma components in the lesion, and positive immunohistochemistry of mouse double minute 2 homolog (MDM2) and cyclin-dependent kinase 4 (CDK4) associated with MDM2 amplification. These patients were then compared with 51 age-matched consecutive conventional osteosarcoma (COS) patients (33 men, 18 women; median age 25 years (IQR 20 to 38)) regarding their clinicopathological features.

RESULTS

The five-year overall survival (OAS) rates in the DLOS and COS patients were 85.7% and 77.1% (p = 0.728), respectively, and the five-year progression-free survival (PFS) rates were 57.7% and 44.9% (p = 0.368), respectively. A total of 12 DLOS patients received chemotherapy largely according to regimens for COS. Among the nine cases with a histological evaluation after chemotherapy, eight showed a poor response, and seven of these had a necrosis rate of < 50%. One DLOS patient developed local recurrence and five developed distant metastases.

CONCLUSION

Based on our study of 13 DLOS cases that were strictly defined by histological and molecular means, DLOS showed a poorer response to a standard chemotherapy regimen than COS, while the clinical outcomes were not markedly different. Cite this article: Bone Joint J 2019;101-B:745-752.

Parosteal osteosarcoma of the fibula in a middle-aged patient: A case report

RATIONALE

Parosteal osteosarcoma (PO) is relatively rare, accounting for about 1% of primary malignant bone tumors and 4% of all osteosarcomas. Onset is generally at approximately 20 to 40 years of age; the distal posterior surface of femur is the most common site, accounting for more than 60% cases. However, PO in middle-aged or elderly patients is extremely rare and PO occurring in the fibula is even rarer. To our knowledge, this is the first case of PO occurring in the fibula of a middle-aged adult.

PATIENT CONCERNS

We present a case of a 47-year-old female who had a lateral mass on her left knee for 3 months with no obvious cause.

DIAGNOSES

The patient was initially diagnosed with a proximal left fibula tumor via x-ray scan at a local hospital. Subsequently, osteochondroma was highly suspected through computed tomography (CT) and magnetic resonance imaging (MRI) obtained at our hospital. Finally, the postoperative pathological report confirmed PO.

INTERVENTIONS

She underwent a complete resection of the left fibula tumor and received postoperative adjuvant chemotherapy.

OUTCOMES

The patient recovered well and was discharged on the 10th day after admission. Additionally, there was no evidence of recurrence at the 4-year follow-up after surgery.

LESSONS

In middle-aged or elderly patients, early diagnosis of PO in the fibula is difficult and misdiagnosis or missed diagnosis is common. In clinical practice, PO is uncommon in middle-aged or elderly patients, occurs more rarely in the peroneal bone, and should be carefully identified. CT and MRI are essential for diagnosis, with pathological examination being effective for confirmation. Because of the limited reports of PO of the fibula in middle-aged or elderly adults, the present case raises awareness of this rare condition.

Dedifferentiated parosteal osteosarcoma of the maxilla: a case report and review of the literature

Background

Parosteal osteosarcomas are usually low-grade tumors, however, sometimes they transform to high-grade tumors, which is named dedifferentiation. This phenomenon has been reported in long bones. Recently, we encountered a patient with dedifferentiated parosteal osteosarcoma occurring in the maxilla. Here, we report a first case of dedifferentiated parosteal osteosarcoma of the head and neck region.

Case presentation

A 45-year-old Japanese woman with a refractory bone lesion in the maxilla presented to our hospital. A biopsy showed atypical spindle cell proliferation involving dedifferentiated high-grade component, which was diagnosed as dedifferentiated parosteal osteosarcoma. Three cycles of neoadjuvant chemotherapy using ifosfamide and pirarubicin were performed followed by sub-total maxillectomy. Histopathological results showed that neoadjuvant chemotherapy was effective for high-grade component. The decision to perform adjuvant chemotherapy (cisplatin and pirarubicin) was made because distant metastasis has been reported, even in cases with dedifferentiated parosteal osteosarcoma in which complete necrosis of high-grade component was achieved due to neoadjuvant chemotherapy. There was no recurrence 15 months after surgery.

Conclusions

Dedifferentiated parosteal osteosarcoma can occur in the head and neck region. Chemotherapy including anthracycline anticancer agent could be effective for high-grade component of dedifferentiated parosteal osteosarcoma.

On the importance of considering disease subtypes: Earliest detection of a parosteal osteosarcoma? Differential diagnosis of an osteosarcoma in an Anglo-Saxon female

A case of potentially dedifferentiated parosteal osteosarcoma was found in the proximal humerus of an adult female buried in the late Anglo-Saxon cemetery of Cherry Hinton, Cambridgeshire, UK. Key features include a large, dense, lobulated mass attached to the medial metaphysis of the proximal humerus by a broad-based attachment, accompanied by cortical destruction and widespread spiculated periosteal reaction. Radiographic images confirm medullary involvement, lack of continuity between the cortex and external mass, a radiolucent cleavage plane and possible radiolucent zones within the bony masses. Differential diagnoses considered include osteochondroma, myositis ossificans, fracture callus, as well as the primary malignancies of osteosarcoma and chondrosarcoma, and their various subtypes. The macroscopic and radiographic analysis of the tumor is described and discussed within clinical and paleopathological contexts. One of only 19 uncontested examples of osteosarcoma from past human populations, most of which remain unconfirmed, this case represents what we believe to be the earliest, and probably singular, bioarcheological example of parosteal osteosarcoma in human history.

Triple primary malignancies of surface osteosarcoma of jaw, myelodysplastic syndrome and colorectal cancer as a second primary cancer detected by PET2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography: A case report

Second primary malignancy (SPM) is a severe issue for cancer survivors, particularly for osteosarcoma (OS) survivors. To date, the associations between subsequent SPM and OS have been well reported. Hematogenic and solid malignancies tend to occur following OS treatment. Reportedly, 2-[¹⁸F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is mainly used in OS patients for initial cancer staging, to evaluate the response of neoadjuvant chemotherapy, and when recurrence or metastasis is clinically suspected. The present case report describes a 70-year-old man diagnosed with three primary malignancies: jaw OS, myelodysplastic syndrome and colorectal adenocarcinoma. To the best of our knowledge, this combination of malignancies has not been reported previously. Until now, there is no specific protocol of postoperative FDG-PET for OS patients. Few studies have described OS follow-up methods; therefore, there is no consensus on proper follow-up methods. In the present case report, the colorectal early-stage SPM was observed, without any symptoms, by FDG-PET/computed tomography. To avoid overlooking solid SPMs, it is suggested that FDG-PET should be performed in the long-term follow-up of OS patients.

Dedifferentiated parosteal osteosarcoma of the calvaria

Dedifferentiated parosteal osteosarcoma is a rare tumor and is even rarer when involving the skull bones. We present a case of a 57-year-old man with a partially ossified progressive enlarging left skull mass in the left temporoparietal region, with erosion of the outer table. Radiological diagnosis of dedifferentiated parosteal osteosarcoma was suggested, and histopathology confirmed the diagnosis.

A Pediatric Case of Metastatic Conventional Parosteal Osteosarcoma Treated With Multidrug Chemotherapy

Parosteal osteosarcoma (POS) is conventionally a low-grade sarcoma with limited metastatic potential; however, the tumor occasionally transforms into a high-grade dedifferentiated POS, which commonly metastasizes to distant organs. The present report describes a rare pediatric case of conventional POS with no dedifferentiated component yet had multiple pulmonary metastases at initial diagnosis. Following limb-sparing surgery and osteosarcoma-oriented neoadjuvant chemotherapy, the patient received total resection of pulmonary metastases. Despite no treatment for pulmonary recurrence 1 year after adjuvant chemotherapy, the patient is alive with stable disease 4 years and 6 months after the initial diagnosis.

The prognostic and therapeutic factors which influence the oncological outcome of parosteal osteosarcoma

The aim of this study was to evaluate the prognostic and therapeutic factors which influence the oncological outcome of parosteal osteosarcoma.

A total of 80 patients with a primary parosteal osteosarcoma were included in this retrospective study. There were 51 females and 29 males with a mean age of 29.9 years (11 to 78).

The mean follow-up was 11.2 years (1 to 40). Overall survival was 91.8% at five years and 87.8% at ten years. Local recurrence occurred in 14 (17.5%) patients and was associated with intralesional surgery and a large volume of tumour. On histological examination, 80% of the local recurrences were dedifferentiated high-grade tumours. A total of 12 (14.8%) patients developed pulmonary metastases, of whom half had either a dedifferentiated tumour or a local recurrence. Female gender and young age were good prognostic factors. Local recurrence was a poor prognostic factor for survival. Medullary involvement or the use of chemotherapy had no impact on survival.

The main goal in treating a parosteal osteosarcoma must be to achieve a wide surgical margin, as inadequate margins are associated with local recurrence. Local recurrence has a significant negative effect on survival, as 80% of the local recurrences are high-grade dedifferentiated tumours, and half of these patients develop metastases.

The role of chemotherapy in the treatment of parosteal osteosarcoma is not as obvious as it is in the treatment of conventional osteosarcoma. The mainstay of treatment is wide local excision.

Cite this article: Bone Joint J 2015;97-B:1698–1703.

Surface osteosarcoma: Clinical features and therapeutic implications

INTRODUCTION

Surface osteosarcoma are rare variant of osteosarcoma that include parosteal osteosarcoma, periosteal osteosarcoma and high grade surface osteosarcoma. These lesions have different clinical presentation and biological behavior compared to conventional osteosarcoma, and hence need to be managed differently.

GOAL

The aim of this study is to analyze the clinico-pathological features and outcome of a series of surface osteosarcoma in an attempt to define the adequate treatment of this rare entity.

PATIENT AND METHOD

It is a retrospective and bicentric study of 18 surface osteosarcoma that were seen at the KASSAB's Institute and SAHLOUL Hospital from 2006 to 2013. The authors reviewed the clinical and radiologic features, histologic sections, treatments, and outcomes in this group of patients.

RESULTS

Seven patients were male (38.9%) and 11 were female (61.1%) with mean age of 25 years (range from 16 to 55 years). Eleven lesions were in the femur and 7 in the tibia. We identified 11 parosteal osteosarcoma (six of them were dedifferentiated), 3 periosteal osteosarcoma and 4 high grade surface osteosarcoma. Six patients had neoadjuvant chemotherapy and all lesions had surgical resection. Margins were wide in 15 cases and intra lesional in 3 cases. Histological response to chemotherapy was poor in all cases. The mean follow up was 34.5 months. Six patients (33.3%) presented local recurrence and 8 patients (44.4%) presented lung metastases. Six patients (33.3%) died from the disease after a mean follow up of 12 months (6-30 months); all of them had high grade lesions.

CONCLUSION

Histological grade of malignancy is the main point to assess in surface osteosarcoma since it determines treatment and prognosis. Low grade lesions should be treated by wide resection, while high grade lesions need more aggressive surgical approach associated to post operative chemotherapy.

GNAS mutations are not detected in parosteal and low-grade central osteosarcomas

Parosteal osteosarcoma, low-grade central osteosarcoma, and fibrous dysplasia share similar histological features that may pose a diagnostic challenge. The detection of GNAS mutations in primary bone tumors has been useful in clinical practice for diagnosing fibrous dysplasia. However, the recent report of GNAS mutations being detected in a significant proportion of parosteal osteosarcoma challenges the specificity of this mutation. As the number of cases reported in this study was small we set out to determine if these results could be reproduced. We studied 97 formalin-fixed paraffin-embedded low-grade osteosarcomas from 90 patients including 62 parosteal osteosarcomas, of which MDM2 amplification was detected in 79%, 11 periosteal osteosarcomas and 24 low-grade central osteosarcoma samples. The mutational status of GNAS was analyzed in codons p.R201, p.Q227, and other less common GNAS alterations by bidirectional Sanger sequencing and/or next generation sequencing using the Life Technologies Ion Torrent platform. GNAS mutations were not detected in any of the low-grade osteosarcomas from which informative DNA was extracted. Our findings therefore support prior observations that GNAS mutations are highly specific for fibrous dysplasia and occur rarely, if ever, in parosteal and other low-grade osteosarcomas.

Reconstruction of bone defect with autograft fibula and retained part of tibia after marginal resection of periosteal osteosarcoma: a case report

Periosteal osteosarcoma is a rare subtype of osteosarcoma. Wide surgical removal is the commonly used treatment-method algorithm. However, the limb-salvage procedure of periosteal osteosarcoma in the distal tibia is a technical challenge to orthopedic surgeons because of the scarcity of soft tissue and subcutaneous nature in the anteromedial aspect. We encountered a 16-year-old female patient with periosteal osteosarcoma in the distal half of the left tibia diagnosed preoperatively based upon the CT images and a needle biopsy. A unique identical surgical technique was applied in the case, including marginal resection of the periosteal osteosarcoma with part of the tibia retained at the same level of bone defect and reconstruction using the autologous fibula graft. A combination of cisplatin and doxorubicin was received as chemotherapy after the operation. Postoperative incisional biopsy was performed, and the hematoxylin-eosin-stained results confirmed the diagnosis of periosteal osteosarcoma. The patient was followed up for 11 years. Radiological and clinical evaluation was performed at each follow-up. The retained tibia incorporated well with the fibula autograft, and excellent limb functional recovery was achieved. The patient was free from neoplastic disease at the latest follow-up. In conclusion, young patients with periosteal osteosarcoma without intramedullary involvement can be treated by marginal resection of the lesion with part of the tibia retained at the level of bone defect and reconstructed using a long autologous fibula graft. Subsequent chemotherapy with administration of cisplatin and doxorubicin is recommended.

Osteoma of long bone: an expanding spectrum of imaging findings

Osteoma of long bone is an extremely rare, benign bone-forming surface lesion with the largest published case series consisting of only 14 patients. The most important and often most difficult lesion to differentiate from osteoma of long bone radiographically is parosteal osteosarcoma, which is a rare, low-grade surface osteosarcoma with the potential for dedifferentiation. Reports of imaging studies of osteoma of long bone depict a well-defined ossified mass arising from the surface of the diaphysis or metadiaphysis of a long bone. A characteristic feature is the homogeneity of the mass, with uniform density near or equal to that of cortical bone from the base of the lesion to its periphery. The 45-year-old female in this case presented with left hip fullness and was subsequently found to have a proximal femoral osteoma, which was unique in that it contained large fatty marrow spaces that corresponded to bands of relatively low density on plain radiography and computed tomography, giving it a heterogeneous appearance atypical of osteoma of long bone. Furthermore, the osteoma reported here was associated with a small but separate nodular focus of ossification in the adjacent soft tissue. These findings led to a presumptive diagnosis of parosteal osteosarcoma with a local soft tissue metastasis or satellite nodule resulting in radical resection of the tumor. Definitive diagnosis of osteoma was made on histology of both the parent lesion and ossified nodule as no neoplastic spindle cell proliferation was present to establish a diagnosis of low-grade osteosarcoma. This represents, to the best of our knowledge, the first such presentation of osteoma of long bone.

Dedifferentiated giant-cell tumor of bone with an undifferentiated round cell mesenchymal component

The dedifferentiated giant-cell tumor of the bone is a very rare variant of the giant-cell tumor (GCT). We report the clinical, radiographic and histological findings of a dedifferentiated GCT in which the dedifferentiated component consisted of small round cells. We also comment on previously reported cases of dedifferentiated GCT, discuss the clinical implications of this dual histology, and analyze the information published about the coexistence of similar genetic abnormalities in GCT and small round cell tumors of the bone.

Parosteal Osteosarcoma

Parosteal osteosarcoma is a rare malignant bone tumor arising from the bone cortical surface. It most commonly occurs in young women over the metaphyseal region, especially the long bones near the knee joint. Patients usually report a slow-growing mass for years. The tumor is characterized by its bland microscopic morphology, prone to be misdiagnosed as other benign tumors. In the absence of dedifferentiation, the prognosis is generally better than that of conventional osteosarcoma. Recent studies demonstrated distinctive cytogenetic abnormality resulting in amplification of the CDK4 and MDM2 genes, which may serve as markers for molecular diagnosis. In this article, we review the clinical, radiologic, and pathologic features of parosteal osteosarcoma and identify some diagnostic pitfalls, discuss the prognostic variables, and update recent molecular advances and their application in the diagnosis.

Surface osteosarcomas: Diagnosis, treatment and outcome

Surface osteosarcomas are a rare form of osteosarcomas accounting for around 3-6% of all osteosarcomas. Three major groups of surface osteosarcomas are parosteal, periosteal and the high grade surface osteosarcomas. Of these, the parosteal osteosarcoma is the most common. Parosteal and periosteal osteosarcomas are distinct clinical entities and it is important to identify the clinicoradiological differences between the two types. Surface osteosarcomas occur at a later age as compared to conventional osteosarcomas. The classical site is the lower end of the femur followed by the upper end of the tibia and upper end of humerus, in that order. The periosteal variant affects the tibia more commonly than the parosteal variety. Neo-adjuvant chemotherapy is the standard of care for high grade surface osteosarcomas. Parosteal osteosarcomas, being low grade lesions, can be treated by upfront wide excision without adjuvant systemic therapy. Controversy prevails over the need for chemotherapy in periosteal osteosarcomas, which are intermediate grade lesions.

Distinct profiles of oxidative stress-related and matrix proteins in adult bone and soft tissue osteosarcoma and desmoid tumors: a proteomics study

Osteosarcomas rarely occur in older adults. Proteomics has not been reported to date in osteosarcoma occurring in the older adult population. This proteomic investigation was conducted to identify differentially expressed proteins in osteosarcoma occurring in various backgrounds from older adults. Desmoid tumors, known to recur locally but not metastasize, were also analyzed. Protein digests isolated from formalin-fixed, paraffin-embedded tumor tissue specimen representing 14 primary osteosarcomas of soft tissue and bone and 18 desmoid tumors were analyzed by high-resolution liquid chromatography-tandem mass spectrometry for protein identification and relative quantification by spectral counting. Elevated abundance levels of several proteins including heat shock protein 90 (HSP90), elastin microfibril interface-located protein 1, and clusterin were identified in osteosarcoma with slight differences in proteomic profiles. Desmoids had an abundance of collagen II and periostin only. The findings were confirmed by immunohistochemical staining for HSP90 and clusterin in the experimental samples and additionally in 16 posttherapy conventional osteosarcomas in tissue microarrays constructed from heterogeneous sarcomas and benign lesions. All osteosarcomas were positive for HSP90 and clusterin to a variable extent. One case of well-differentiated parosteal osteosarcoma was negative. Thirty of 75 other high-grade sarcomas including cases of chondrosarcoma were positive for HSP90. Low-grade and benign lesions and scars and 18 desmoid tumors had little or no expression of these proteins. HSP90 and clusterin represent candidate markers of aggressiveness in osteosarcoma occurring in older adults and may be indicative of drug resistance.

Solitary bone lesions: which ones to worry about?

The question is not classic: which signs suggest a possible malignancy when faced with a solitary bone lesion? Usually radiologists try to identify the leave me alone lesions, for which nothing is needed. Here we consider the suspicious lesions. Clinical and radiological indicators are proposed, leading to a probability. Nowadays, a biopsy is nevertheless always requested before treating a malignant lesion, even if suspicion is very high. But histology should integrate with the radiological signs.

[Parosteal osteosarcomas: unusual findings]

OBJECTIVE

To study and evaluate the unusual findings in the natural history of parosteal osteosarcomas. Parosteal osteosarcomas are well-differentiated tumours of low grade malignancy, but may dedifferentiate into a more aggressive lesion.

MATERIAL AND METHODS

We reviewed 7 parosteal osteosarcomas treated in La Paz Hospital between 2005 and 2009 (3 were dedifferentiated parosteal osteosarcomas). The authors analysed the clinical and radiological features, histology, treatment and outcomes in this patient group.

RESULTS

There were 5 men and 2 women, with a mean age of 32.14 years, range 24-47 years. Three of seven tumours (42.8%) were dedifferentiated osteosarcomas. All three patients received chemotherapy. One patient presented with pulmonary metastases. No patient died.

CONCLUSIONS

It is important to understand that the biological phenomenon of dedifferentiation can occur in parosteal osteosarcomas. The prognosis, treatment and survival changes radically.