Low-grade Central Osteosarcoma Research Articles

Living with a tumor: A case of osteosarcoma involving the medullary region in Phrynops cf. P. geoffroanus (Testudines: Chelidae).

The individual Geoffroy's side-necked turtle, Phrynops cf. P. geoffroanus, was diagnosed postmortem with osteosarcoma associated with the forelimb through morphological and histological analysis. Osteosarcoma stands as the most prevalent primary malignant bone tumor in tetrapods. The tumor presents itself as a large mass in the distal epiphysis, characterized by spicular outgrowths and a rugose external texture. Histologically, the afflicted humerus displayed a high degree of vascularity and exhibited an extensive bone resorption process involving the medullary and endosteal regions. Notably, a clear transition between the bone marrow and cortical bone was absent, indicative of a remodeling process featuring Haversian bone system apposition. Additionally, the diaphyseal region displayed the progression of neoplastic bone tissue along the bone. For comparative purposes, we describe a humeral thin section from a healthy specimen revealing compact primary bone interrupted by cyclical growth marks which differs from the continuous growth observed in the neoplastic humerus. To assess the neoplastic bone growth rate at the mid-diaphysis level, phylogenetic eigenvector maps (PEM) were employed, utilizing osteocyte density and vascular density as explanatory variables. The findings indicated that the osteosarcoma exhibited a slow-growing nature, suggesting that the turtle had to live with this condition for years. As the neoplasia continued to expand, it likely led to disadvantages for the pathological Phrynops individual due to humeral deformity. Furthermore, malignancy was associated with angiogenesis and the invasion of the medullary region by neoplastic bone tissue, raising the likelihood of metastasis as an additional factor contributing to the individual's sickness. The presence of numerous vascular canals in the diaphyseal thin section suggested a low-grade central osteosarcoma. It is worth noting that osseous neoplasms are rarely documented in Testudines, making this case of osteosarcoma in a South American freshwater chelid specimen a unique and rare occurrence.

Synchronous Low-Grade Central Osteosarcoma and Ewing Sarcoma: A Rare Case Report.

A 23-year-old female patient presented with radicular back pain, perineal numbness, and urinary retention. The patient was diagnosed with cauda equina syndrome and magnetic resonance imaging (MRI) of the spine revealed an enhancing osseous lumbar lesion causing severe central stenosis. A core needle biopsy of the lumbar spine showed microscopic features compatible with a small round blue cell tumor. CD99 and FLI1 were positive in the tumor cells. Next-generation sequencing demonstrated a EWSR1::FLI1 fusion. Given these findings, the spine lesion was diagnosed as Ewing sarcoma. The patient underwent surgical decompression of L2. On further workup, an MRI revealed an ill-defined enhancing mass of the right distal femur. This area was biopsied, demonstrating a fibro-osseous lesion with osteoblast proliferation containing nuclear atypia, low mitotic activity, and SATB2 positivity, diagnosed as low-grade central osteosarcoma (LGCOS). The patient underwent resection, which showed a classic LGCOS by histomorphology. Although fluorescence in-situ hybridization study for MDM2 gene amplification was negative, the overall findings are most consistent with LGCOS. These neoplasms are considered to be synchronous due to the presentation of each entity within 6 months. Considering the aggregate yearly incidence of Ewing sarcoma (approximately 1 case per 750 000 per year) and LGCOS (approximately 1 case per 10 million per year), the aggregate yearly probability of developing both of these genetically unrelated tumors in a single individual is 1 per 7.5 trillion per year, and it is likely such an event has never happened in the past.

Low-grade central osteosarcoma with extraosseous dedifferentiation: a rare case.

Low-grade central osteosarcoma (LGCOS), which arises from the intramedullary cavity of the metaphysis of long bones, occasionally exhibits extraosseous spread. Approximately 10-30% of patients with LGCOS exhibit dedifferentiation, but it is rare to experience a primary tumor with a dedifferentiated component. A 38-year-old female patient presented with right knee pain for two months. Imaging studies revealed a bone mass with extraosseous involvement. Wide resection was performed, and pathologic examination led to the diagnosis of LGCOS with a dedifferentiated extraosseous lesion. A single defect in the bone cortex constituted the boundary between the low- and high-grade components. The extraosseous high-grade component included more tumor cells with p53 overexpression and more murine double minute 2 (MDM2) copies compared with the low-grade component. These genetic mutations and copy number alterations can be associated with malignant transformation of LGCOS.

Detection of MDM2 gene amplification by fluorescence in situ hybridization and its diagnostic value in low-grade osteosarcoma

Objective: To investigate the diagnostic value of detecting MDM2 gene amplification by fluorescence in situ hybridization (FISH) in low-grade osteosarcoma (LGOS). Methods: Thirty cases of parosteal osteosarcoma (POS) and 14 cases of low-grade central osteosarcoma (LGCOS) from April 2009 to August 2022 at Beijing Jishuitan Hospital, Capital Medical University were analyzed for the presence of MDM2 gene amplification by FISH. Fifty-eight additional cases were used as negative controls (including 28 cases of fibrous dysplasia, 5 cases of giant cell tumor, 4 cases of conventional osteosarcoma, 2 cases each of periosteal osteosarcoma, reparative changes after fracture, pleomorphic undifferentiated sarcoma, low grade myofibroblastic sarcoma, fibrous dysplasia with malignant transformation, one case each of leiomyosarcoma, sclerosing epithelioid fibrosarcoma, malignant peripheral nerve sheath tumor, desmoplastic fibroma of bone, solitary fibrous tumor, aneurysmal bone cyst, clear cell chondrosarcoma, osteofibrous dysplasia, and 3 cases of unclassified spindle cell tumor). Results: Among the 30 patients with POS, 15 were male and 15 were female, ranging in age from 10 to 59 years (mean 35 years, median 30.5 years). Among the 14 patients with LGCOS, four were male and 10 were female, ranging in age from 15 to 56 years (mean 37 years, median 36 years). All except one case were successfully detected by FISH. MDM2 gene amplification was detected in 27 cases of POS (27/29,91.3%) and 8 cases of LGCOS (8/14). All the negative controls were negative for MDM2 gene amplification. The positive rate of MDM2 gene amplification was significantly different between the case group and the control group (P<0.05). The sensitivity and specificity of MDM2 gene amplification in diagnosing POS and LGCOS were 91.3% and 100.0%; and 57.1% and 100.0%, respectively. The sensitivity and specificity of MDM2 gene amplification in diagnosing LGOS (including POS and LGCOS) were 81.3% and 100.0%, respectively. In cases where MDM2 gene was amplified, the MDM2 amplified signal was clustered. Nine cases showed increased CEP12 signal different from polyploidy which was displayed as small and weak signal points or cloud flocculent and cluster signals. Conclusions: Detection of MDM2 gene amplification by FISH is a highly sensitive and specific marker for LGOS. The interpretation criteria for FISH detection of MDM2 amplification are currently not unified. The signal characteristics need more attention when interpreting.

Diagnostic challenges in low-grade central osteosarcoma.

Low-grade central osteosarcoma (LGCOS), a rare type of osteosarcoma, often has misleading radiological and pathological features that overlap with those of other bone tumours, thereby complicating diagnosis and treatment. We aimed to analyze the clinical, radiological, and pathological features of patients with LGCOS, with a focus on diagnosis, treatment, and outcomes. We retrospectively analyzed the medical records of 49 patients with LGCOS (Broder's grade 1 to 2) treated between January 1985 and December 2017 in a single institute. We examined the presence of malignant features on imaging (periosteal reaction, cortical destruction, soft-tissue invasion), the diagnostic accuracy of biopsy, surgical treatment, and oncological outcome. Based on imaging, 35 of 49 patients (71.4%) exhibited malignant features. Overall, 40 of 49 patients (81.6%) had undergone a biopsy before en-bloc resection: 27 of 40 patients (67.5%) were diagnosed on the first biopsy, which was more accurate when carried out by open rather than needle biopsy (91.3% vs 35.3% diagnostic accuracy, respectively; p < 0.001). Of the 40 patients treated by en-bloc resection, surgical margins were wide in 38 (95.0%) and marginal in two (5.0%). Furthermore, nine of 49 patients (18.4%) underwent curettage (intralesional margin) without previous biopsy. All patients with a positive margin developed local recurrence. Distant metastases occurred in five of 49 patients (10.2%). The mean five-year overall survival (OS) and distant relapse-free survival (D-RFS) were 89.3% (SD 5.1%) and 85.7% (SD 5.5%), respectively. Univariate analysis showed that the occurrence of distant metastasis was a poor prognostic factor for OS (hazard ratio 11.54, 95% confidence interval (CI) 1.92 to 69.17; p < 0.001). Local recurrence was a poor prognostic factor for D-RFS (HR 8.72, 95% CI 1.69 to 45.0; p = 0.002). The diagnosis of LGCOS can be challenging because it may present with non-malignant features and has a low diagnostic accuracy on biopsy. If precisely diagnosed, LGCOS can be successfully treated by surgical excision with wide margins.

Sarcoma care in the era of precision medicine.

Sarcoma subtype classification is currently mainly based upon histopathological morphology. Molecular analyses have emerged as an efficient addition to the diagnostic workup and sarcoma care. Knowledge about the sarcoma genome increases, and genetic events that can either support a histopathological diagnosis or suggest a differential diagnosis are identified, as well as novel therapeutic targets. In this review, we present diagnostic, therapeutic, and prognostic molecular markers that are, or might soon be, used clinically. For sarcoma diagnostics, there are specific fusions highly supportive or pathognomonic for a diagnostic entity-for instance, SYT::SSX in synovial sarcoma. Complex karyotypes also give diagnostic information-for example, supporting dedifferentiation rather than low-grade central osteosarcoma or well-differentiated liposarcoma when detected in combination with MDM2/CDK4 amplification. Molecular treatment predictive sarcoma markers are available for gastrointestinal stromal tumor (GIST) and locally aggressive benign mesenchymal tumors. The molecular prognostic markers for sarcomas in clinical practice are few. For solitary fibrous tumor, the type of NAB2::STAT6 fusion is associated with the outcome, and the KIT/PDGFRA pathogenic variant in GISTs can give prognostic information. With the exploding availability of sequencing technologies, it becomes increasingly important to understand the strengths and limitations of those methods and their context in sarcoma diagnostics. It is reasonable to believe that most sarcoma treatment centers will increase the use of massive-parallel sequencing soon. We conclude that the context in which the genetic findings are interpreted is of importance, and the interpretation of genomic findings requires considering tumor histomorphology.

Limb Salvage Surgery Using Autogenous Irradiated Bone Graft for Low-grade Central Osteosarcoma of the Distal Tibia: A Case Report

Limb Salvage Surgery Using Autogenous Irradiated Bone Graft for Low-grade Central Osteosarcoma of the Distal Tibia: A Case Report

Three-Dimensional Printed Custom-Made Prostheses after Partial Scapulectomy: A Case Report

This case study focuses on scapula reconstruction using three-dimensional printing in a patient with low-grade osteosarcoma. Malignant tumors originating from the scapula often lead to destructive surgery, with poor functional status and quality of life for the patients. Using custom prosthetic technology through three-dimensional printing could be a possible solution for reconstruction with greater long-term functional outcomes. This study aims to assess the functional outcomes of the reconstruction. A 39-year-old patient with low-grade central osteosarcoma involving the lateral two-thirds of the scapula underwent a custom prosthetic reconstruction. The patient subsequently followed a rehabilitation protocol for 12 months. The results indicate that even though there was a slight decrease in the range of movement, and an increase in the disabilities of the arm, shoulder, and hand (DASH) score, no relevant increase in activities of daily living (ADL) disability was present at follow-up. The patient returned to carry out his daily activities without pain and with a minimal functional reduction in movement. In conclusion, three-dimensional prosthetic reconstruction is a valid alternative for scapula reconstruction, allowing excellent functional and aesthetic results in oncological cases.

Polyostotic Fibrous Dysplasia in a Six-year-Old Boy.

Fibrous dysplasia (FD) is a rare congenital benign bone disease that manifests as a defect in the bone remodeling process, affecting the function, differentiation, and maturation of osteoblasts. This process is located in the bone marrow, where the normal marrow tissue is replaced with immature bone islands and fibrous stroma. The etiology is unclear so far, but it is known to be connected with a point mutation of the gene that encodes Gs α protein at the time of embryogenesis, and because of that, all of the affected somatic cells become dysplastic. It is important to determine whether the mutation occurred earlier in the process of embryogenesis so that there will be more mutant cells and the disease will appear in a more severe form. The clinical presentation of FD is variable, so there are plenty of potential differential diagnoses. The most common include Paget disease, non-ossifying fibroma, osteofibrous dysplasia, aneurysmal bone cyst, adamantinoma, giant cell tumor, fracture callus, and low-grade central osteosarcoma.

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

To present our experience on osteosarcomas of the hands and review the existing literature pertaining osteosarcomas in this extremely rare location. 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 33mm. 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. 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.

Low-grade central osteosarcoma of the hallux with a 7-year undiagnosed course: Case report

Low-grade central osteosarcoma usually exhibits a long course with nonspecific symptoms, while the imaging and histological findings may be easily confused with a variety of benign fibroosseous lesions. A 15-year-old boy was referred for a painless swelling of the proximal phalanx associated with shortening of the right hallux. A benign cystic bone lesion complicated by a pathological fracture had been diagnosed on the radiographs at 8 and 10 years of age after sport injuries. He was referred for evaluation and treatment of the bone lesion. Magnetic resonance imaging and computed tomography were performed. A referral centre was contacted, since there was a strong evidence of malignancy. An open biopsy was suggested, which indicated bone malignancy. The patient was then referred to the specialized tumor centre. A new biopsy was performed there, since the previous sampling was considered insufficient or inadequate to secure a differentiation from fibrous dysplasia. It ensured the diagnosis of low-grade central osteosarcoma. Radical excision of the proximal phalanx and reconstruction of the defect with an iliac graft associated with arthrodesis of both the hallux metatarsophalangeal and interphalangeal joints was the treatment of choice. Disturbed wound healing necessitated hardware removal 4 months postoperatively. No further interventions were required in the follow-up. Clinical and radiographic evaluation at 12 years confirmed no evidence of local recurrence or distant metastasis. The patient was satisfied with the final outcome and reported unrestricted participation to physical activities and sports. • The rarity and the highly variable presentation of the foot and ankle malignancies may explain why they are often not considered in the differential diagnosis and the increased likelihood of delayed or incorrect diagnosis. • A low-grade central osteosarcoma localized in the proximal phalanx of the great toe of a 15-year-old boy is presented. The imaging appearance of the lesion was not correctly assessed to suggest a potentially malignant pathology and to require an early bone biopsy leading to a 7-year delayed diagnosis. • All available clinical and imaging features should be carefully considered in decision making, during the diagnostic steps in a patient with a potentially malignant bone tumor of the foot or ankle, to ensure that the diagnosis will not be delayed or missed and that proper treatment by a specialized tumor surgeon in a designated tumor centre will be offered.

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

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. 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). 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. 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.

Bone and soft tissue tumors at the borderlands of malignancy.

This review examines findings of musculoskeletal neoplasms whose equivocal imaging and/or histopathologic features make it difficult to determine if they will show aggressive behavior. We include both intermediate tumors as defined by the World Health Organization (WHO), and a single low-grade malignancy, low-grade central osteosarcoma, which mimics a benign lesion on imaging and histology. Intermediate tumors are a broad category and are subdivided into tumors that have risk of local recurrence only, and ones that have a risk of distant limb and pulmonary metastases. Difficult intermediate musculoskeletal lesions include atypical cartilaginous tumor/grade 1 chondrosarcoma, atypical lipomatous tumor/grade 1 liposarcoma, and solitary fibrous tumor. We review diagnostic criteria, differential diagnosis, and recommendations for surveillance.

Osteosarcoma of Jaw Masquerading as Calcifying Epithelial Odontogenic Tumour- A Diagnostic Dilemma

Osteogenic osteosarcoma is the most widely recognised primary malignant bone tumour involving particularly the appendicular skeleton. Osteosarcoma of jaw including maxillary and mandibular osteosarcoma accounts for about 7% of cases. The variants of osteosarcoma involving jaw include- osteosarcoma, Not Otherwise Specified (NOS) Low grade central osteosarcoma; chondroblastic osteosarcoma; parosteal osteosarcoma; periosteal Osteosarcoma. The present case was a 27-year-old male who came to the dental Outpatient Department (OPD) with the complaints of swelling in the upper vestibule and loosening of upper alveolar teeth and was reported as Calcifying Epithelial Odontogenic Tumour (CEOT) on histopathological examination and excision of the lesion was done. After two months the patient again presented with a recurrent lytic and sclerotic lesion involving the left maxillary bone with soft tissue extension in the maxillary sinus. Provisional diagnosis was made as malignant transformation of CEOT and immunohistochemistry was performed for the confirmation of the diagnosis. This case represented the challenges in the diagnosis of osteosarcoma of jaw which can be due to difficult biopsy procedure; limited imaging and challenges in legitimate resection because of the proximity to essential structures and the challenges are being faced to get the optimal treatment of jaw osteosarcoma.

Low grade central osteosarcoma transforming to high grade sarcoma – Clinical implications and brief review of literature !

Low grade central osteosarcoma (LGCO) are rare intramedullary bone tumours of adolescents and young adults with an excellent prognosis. They have a predilection for long bones around the knee joint, but cases have been reported in long bones of arm, tarsals and flat bones of jaw, ribs and scapula as well. Their transformation to high grade sarcomas are rarely seen. We report a case of an 16 years female who presented with complaints of progressive pain in the lower thigh 2 years back. Her x-ray suggested a simple bone cyst in distal femur, following which wide excision of the cyst was done. Histopathology however showed features of LGCO. The patient was apparently alright in the follow up period until 9 months ago when the patient had a recurrence of swelling accompanied with pain at the same site leading to difficulty in walking. This time her X-ray showed neoplastic changes after which the tumor was excised. On microscopy, areas of high grade sarcoma with soft tissue extension were seen predominantly. This case is being reported to make the clinicians and diagnosticians aware of the rare but highly significant implication of transformation of LGCO to high grade tumors as it carries a guarded prognosis and calls for a different treatment strategy compared to conventional LGCO. Low grade central osteosarcoma (LGCO) are rare intramedullary bone tumors seen in adolescents and young adults. It bears an excellent prognosis. We present a case report on LGCO showing transformation to a high grade sarcoma that radically changes its prognosis as well as calls for a different treatment strategy.

Post-Denosumab-Treated Giant Cell Tumor of Bone: A Retrospective Histomorphological and Immunohistochemical Study

Abstract Introduction Giant cell tumors of bone (GCTBs) are treated with surgery with or without local adjuvants. Denosumab is a human monoclonal antibody that has recently emerged to be effective in treating unresectable and recurrent GCTBs. Objective In this study, we analyzed the histomorphological changes in GCTB following treatment with denosumab. The expression of histone mutation H3.3G34W by immunohistochemistry (IHC) using mutant specific antibody was also determined. Materials and Methods Of the total 109 GCTBs encountered during the study period, 14 cases with neoadjuvant denosumab therapy were analyzed retrospectively. The post-treatment changes on histopathology were examined on routine hematoxylin and eosin-stained sections. IHC was done using antihistone H3.3G34 antibodies. Statistical analysis was limited to descriptive statistics. No hypothesis testing was performed. Results All these cases except three showed fibrosis with areas of hyalinization, prominent newly formed woven bone along with spindle cells in short fascicles and storiform pattern. There was complete absence and marked reduction in osteoclast-like giant cells in six and five patients, respectively. Only three patients showed a substantial amount of residual osteoclast-like giant cells. IHC with antihistone H3.3G34W antibody showed unequivocal nuclear positivity in the mononuclear cells in nine cases. The mononuclear cells rimming and entrapped within the woven bone were also positive on IHC. The spindle cells in the benign fibrous histiocytoma-like areas and septa of aneurysmal bone cyst-like areas also retained nuclear staining. Conclusion Awareness of post-denosumab-related histopathological changes are necessary to avoid misdiagnosis as fibroosseous lesion and low-grade central osteosarcoma. Expression of mutant-specific H3.3 G34W antibody suggests that the neoplastic stromal cells are largely retained after denosumab therapy. The positive staining of cells both within and those rimming the newly formed woven bone point toward osteoblastic phenotype of the neoplastic stromal cells.

Low‐grade osteosarcoma is predominant in gnathic osteosarcomas: A report of seven cases of osteosarcoma of the jaw

ObjectivePrimary osteosarcoma of the jaw bones is very rare, and histological features of gnathic osteosarcoma remain obscure. The purpose of this study was to describe the clinicopathological features of gnathic osteosarcoma.Materials and methodsSeven cases of gnathic osteosarcoma from Japan diagnosed during the period between 2000 and 2016 were examined retrospectively. The histology of the surgical pathology materials was reviewed by two pathologists. Clinical information was obtained from the hospital's information system.ResultsOf the seven cases, two patients had secondary osteosarcomas. As for the five cases of primary osteosarcoma, their ages ranged from 26 to 58 years (mean: 36.2, median: 28). Histologically, three cases were fibrotic tumors composed of spindle‐shaped cells with mild to moderate nuclear atypia and the collagenous stroma accompanied by woven bones or mature lamellar‐like bones. Two cases had cartilage formation. MDM2 and CDK4 expression was observed in two out of three cases on immunostaining. The histopathology of these three cases was regarded as the counterpart of low‐grade osteosarcomas, namely, parosteal osteosarcoma and low‐grade central osteosarcoma, arising in long bones.ConclusionsThe surprisingly high incidence (60%, 3/5 cases) of low‐grade osteosarcoma explains the reason why gnathic osteosarcomas present a more favorable prognosis than osteosarcomas arising in long bones. Furthermore, it provides insight into the tumorigenesis mechanism of low‐grade osteosarcomas arising in the jaw and other sites.

Imaging findings in low-grade central osteosarcoma

Imaging findings in low-grade central osteosarcoma

A case of low-grade central osteosarcoma of the mandible

Low-grade central osteosarcoma, a rare subtype of osteosarcoma, is less aggressive than conventional osteosarcoma. We report ac case of low-grade central osteosarcoma of the mandible. A 52-year-old woman presented to our department for treatment of a swelling in the right side of the mandible. Computed tomography revealed ground glass radiopaque lesions associated with an expansive growth pattern in the mandibular bone. Because a suspicion of low-grade central osteosarcoma was diagnosed In the biopsy sample provided from the previous hospital, the lesion was surgically resected. Histopathologically, the tumor consisted of a dense proliferation of spindle cells with mild atypia. At the periphery of the lesion, the normal cortical bone was invaded by tumor nests. Low-grade central osteosarcoma was diagnosed in the surgical specimen. Tumor recurrence has not been observed for more than 6 years after surgery. Low-grade central osteosarcoma is hard to differentiate from osteogenic benign neoplasm or bone malformation. Therefore, when radiographic findings reveal an expansive ground glass appearance, a bone biopsy including the normal cortical bone and the central part of the lesion is essential.

Chondromyxoid fibroma-like osteosarcoma: a case series and literature review

BackgroundChondromyxoid fibroma-like osteosarcoma (CMF-OS) is an exceedingly rare subtype of low-grade central osteosarcoma (LGCO), accounting for up to 10% of cases and making it difficult to diagnose. CMF-OS is frequently misdiagnosed on a radiological examination and biopsy, even after the initial operation. Its treatment is a controversial issue due to its low-grade classification and actual high-grade behavior.Case presentationWe retrospectively reviewed the medical charts of more than 2000 osteosarcoma patients between 2008 and 2019; 11 patients with CMF-OS were identified, of which six patients were treated by our institution with complete clinical characteristics, including treatment and prognosis, radiological and pathological features were reviewed. Three males and three females with a median age of 46 (range 22–56) years were pathologically proven to have CMF-OS. The radiological presentation of CMF-OS is variable, thus radiological misdiagnoses are common. However, one must not ignore a malignant radiologic appearance. The most distinctive pathological feature conferring the diagnosis of CMF-OS is the presence of osteoid production directly by the tumor cells under a chondromyxoid fibroma (CMF)-like background. Differential diagnoses based on comprehensive data from CMF, LGCO, chondrosarcoma (CHS), conventional osteosarcoma (COS), etc., are needed. All patients were treated with an operation and chemotherapy, and one patient received additional radiotherapy. Nevertheless, recurrence and metastasis are common in CMF-OS patients. Relatively invasive biological behavior of CMF-OS is against the low-grade classification of this disease.ConclusionsIt is important to recognize CMF-OS and distinguish it from CMF, CHS, COS and other LGCOs. CMF-OS has a relatively poor prognosis despite its low-grade classification.