Telangiectatic osteosarcoma: Outcome analyses and a diagnostic model for differentiation from aneurysmal bone cyst

Telangiectatic osteosarcoma of the thoracic vertebra: a case report and literature review

Telangiectatic osteosarcoma (TOS) is a rare high-grade malignant tumour found primarily in the metaphysis of long bones, but can also occur in the pelvis, spine and skull. Characterized by extensive vascular dilatation and aggressive behavior, TOS often has a poor prognosis and may be misdiagnosed due to similarities with other lesions. This report presents a case of TOS of the thoracic vertebrae and reviews the relevant literature to enhance clinical awareness. A 44-year-old woman presented with chest and back pain of worsening over two months, accompanied by lower limb numbness and incomplete paralysis. Initial treatment for "low back pain" proved ineffective. Imaging showed osteolytic destruction at T10, which led to surgery, and the tumour was classified as Tomita type III. The tumour was surgically resected, showing vascular proliferation and malignant stromal cells, confirming the pathological diagnosis of TOS. However, she developed complications requiring further surgery for recurrent problems, where a hematoma was discovered. Despite interventions, the patient's condition deteriorated, leading to the diagnosis of pulmonary metastasis and eventual death three months after the second surgery. This case highlights the need for increased awareness and accurate diagnosis of TOS, particularly in atypical presentations.

Capillary telangiectatic osteosarcoma misdiagnosed as aneurysmal bone cyst in a 12-year-old girl: A case report

INTRODUCTION AND IMPORTANCE

Telangiectatic osteosarcoma (TOS) is a rare and aggressive subtype of osteosarcoma that is often misdiagnosed as more benign lesions, such as aneurysmal bone cysts (ABCs) or giant cell tumors (GCTs). The accurate differentiation between these conditions is crucial to ensure timely and appropriate treatment, as misdiagnosis can lead to delayed management and poor prognoses.

CASE PRESENTATION

We present the case of a 12-year-old girl who initially presented with left hip and proximal thigh pain, with imaging studies suggesting an ABC. Following curettage and grafting, the initial pathology report confirmed the diagnosis of ABC. However, the patient experienced rapid recurrence within two months, leading to further surgical intervention. A thorough re-evaluation of the pathological specimen revealed characteristics consistent with TOS, confirmed by immunohistochemical staining and molecular tests. The patient received four cycles of chemotherapy after the second surgery and underwent limb - salvage surgery 3 months after the operation.

CLINICAL DISCUSSION

This case highlights the challenges in diagnosing TOS due to its histological similarity to other giant cell-rich lesions. The initial misdiagnosis delayed the commencement of appropriate treatment. However, upon correct identification, the patient was treated with an effective chemotherapy regimen, including cisplatin, doxorubicin, and ifosfamide, resulting in significant tumor regression and control of lung metastases.

CONCLUSION

This case underscores the necessity for clinicians to maintain a high index of suspicion for TOS when evaluating aggressive bone lesions, particularly in pediatric patients. The importance of comprehensive pathological assessment, including immunohistochemistry and molecular analysis, cannot be overstated, as early and accurate diagnosis significantly influences treatment outcomes and prognosis.

Are Pathologic Fractures in Patients With Osteosarcoma Associated With Worse Survival Outcomes? A Systematic Review and Meta-analysis

BACKGROUND

Pathologic fractures occur in 5% to 10% of patients with osteosarcoma, and prior studies have suggested they are prognostically important. However, because they represent an uncommon event in the setting of an already rare disease, most studies fail to reach conclusive findings, and there is no agreement about how best to treat pathologic fractures.

QUESTIONS/PURPOSES

(1) Is the occurrence of a pathologic fracture in patients with osteosarcoma associated with poorer overall survivorship? (2) Is the occurrence of a pathologic fracture in patients with osteosarcoma associated with poorer local recurrence-free survival or metastasis-free survival? (3) Is the surgical approach (amputation or limb salvage) associated with differences in local recurrence rates in patients with osteosarcoma with pathologic fractures?

METHODS

This systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Our study was registered in PROSPERO (ID: 380459). A search of the PubMed and Embase databases resulted in 625 and 747 titles, respectively. After application of the inclusion and exclusion criteria, 21 articles were finally included. Quality assessment of all studies was performed using the Newcastle-Ottawa Quality Assessment Scale. The Risk of Bias In Non-Randomized Studies of Interventions tool was used in the 11 articles that evaluated the effect of an intervention (amputation or limb salvage) on local recurrence rates. The relative risk (RR) was calculated to compare outcomes in patients with osteosarcoma with pathologic fractures and those without. Heterogeneity among studies was calculated using the I 2 statistic. The pooled RR was calculated using the fixed-effects or random-effects model depending on study heterogeneity. The fragility index and the ratio between the fragility index and the total number of participants for each outcome was additionally calculated to assess the robustness of our results. A total of 7604 patients with osteosarcoma, 12% of whom (885) had pathologic fractures, were included in our analysis.

RESULTS

Pathologic fractures in patients with osteosarcoma were associated with lower 3-year (RR 1.53 [95% CI 1.29 to 1.82]; p < 0.001) and 5-year overall survival (RR 1.27 [95% CI 1.16 to 1.40]; p < 0.001). No difference in recurrence rates was found between patients with osteosarcoma with pathologic fractures and those without (RR 1.22 [95% CI 0.91 to 1.64]; p = 0.18). However, having a pathologic fracture was associated with an increased risk of developing metastasis (RR 1.33 [95% CI 1.08 to 1.63]; p = 0.01). Treatment with limb salvage surgery was not associated with a higher rate of local recurrence (RR 1.58 [95% CI 0.88 to 2.85]; p = 0.13).

CONCLUSION

In light of these findings, surgeons should be aware that after appropriate case selection, patients with osteosarcoma and pathologic fractures undergoing limb salvage surgery may have similar rates of local recurrence to those undergoing amputation. Therefore, a pathologic fracture may no longer be an absolute contraindication for limb salvage surgery. Future studies adjusting for potential confounders such as tumor size, tumor location, and response to neoadjuvant therapy would provide further insight into the effect of pathologic fractures on our assessed outcomes.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Primary aneurysmal bone cyst of hands and feet: A series of 14 cases

Aneurysmal bone cyst (ABC) is a relatively rare, benign bone tumor that occurs exceptionally in the hands and feet. The objective of this article is to present clinical, radiological, histopathological features and management of a series of 14 primary ABC cases in these unusual locations. Eight cases occurred in hands and six in feet. We present the first reported subungual case to occur in the hand. The average age of the patients was 26 years (range 7 to 49), with half being over the age of twenty at diagnosis. The male to female ration was 9:5. In radiological terms, ABC appeared as an expansive lesion with internal septa and without cortical disruption. Twelve cases displayed the classic multicystic morphology and two cases were of the solid variant. "Blue bone" was detected in 50 % of the specimens. Treatment consisted of curettage, excision, or amputation in all cases. Recurrence rate was observed in 35 % of the cases, with the similar ABC morphology as the original samples. New therapeutic options have been proposed on their own or in combination with surgery to reduce local recurrence rates.

Indoleamine 2,3-dioxygenase 1 promotes osteosarcoma progression by regulating tumor-derived exosomal miRNA hsa-miR-23a-3p

Background: Osteosarcoma (OS) is the most common primary malignant tumor originating in bone. Immunosuppressive enzyme indoleamine 2,3-dioxygenase 1 (IDO1) participates in tumor immune tolerance and promotes tumor progression, while the study of IDO1 in OS is limited. Methods: Immunohistochemistry analysis was performed to test the expression of IDO1 and Ki67. The relationship between IDO1 or Ki67 positive count and clinical stage of the patient was analyzed. Laboratory test indexes including serum alkaline phosphatase (ALP), lactate dehydrogenase (LDH), white blood cell (WBC) count and C-reactive protein (CRP) at diagnosis of OS patients were collected. The relationship between positive count of IDO1 and Ki67 or laboratory test indexes was analyzed by Pearson's correlation analysis. IDO1 stably overexpressed cell lines of these cells (MG63 OE, 143B OE and hFOB1.19 OE) were constructed and validated by Western blot and Elisa. Exosomes were isolated from conditioned culture media of these cells and were identified by Zetaview nanoparticle tracking analyzer. Next-generation sequencing was conducted to identify miRNAs enriched in exosomes. Differentially expressed miRNAs (DE miRNAs) were verified in clinical samples and cell lines by qPCR. Biological processes and cell components analysis of DE miRNAs was conducted by GO enrichment analysis using the protein interaction network database. Results: Immunosuppressive enzyme IDO1 was highly expressed in tumor tissues. 66.7% (6/9) of the tissues showed moderately or strongly positive immunostaining signal of IDO1, and 33.3% (3/9) were weakly positive. The expression of IDO1 was positively related to Ki67 and associated with prognostic-related clinical features of OS patients. Overexpression of IDO1 significantly affected the exosome-derived miRNA subsets from MG63, 143B and hFOB1.19 cells. A total of 1244 DE miRNAs were identified, and hsa-miR-23a-3p was further screened as key DE miRNA involved in the progression of OS. GO analysis of target genes of the DE miRNA results showed that target enrichment in the functions of immune regulation and tumor progression. Discussion: Our results indicate that IDO1 has the potential to promote the progression of OS that is related to miRNAs mediated tumor immunity. Targeting IDO1-mediated hsa-miR-23a-3p may be a potential therapeutic strategy for OS treatment.

Prognostic analysis of telangiectatic osteosarcoma of the extremities

Background and objectives

Telangiectatic osteosarcoma (TOS) is a rare but highly malignant subtype of osteosarcoma. Although surgical treatment is the primary treatment modality for osteosarcoma, evidence on the benefits of different surgical methods in patients with TOS is lacking. This study aimed to compare the effects of different surgical and adjuvant treatments on overall survival of TOS, and the association of patient demographics, oncological characteristics, and socioeconomic status on treatment outcomes.

Method

This retrospective study selected the most common TOS cases of the extremities registered in the Surveillance, Epidemiology, and End Results (SEER) database from 1989 to 2019. Univariate and multivariate Cox regression models were used to analyze all prognostic factors, and Kaplan-Meier analyses were performed for disease-specific treatment factors of survival.

Result

A total of 127 patients were included in the analysis. The average age at initial diagnosis was 20.09 years. In univariate analyses, the absence of metastasis at initial diagnosis, limb-salvage surgery, adjuvant chemotherapy, and no regional lymph node dissection were associated with a lower risk of death. Multivariate analysis further showed that the presence or absence of distant metastasis and regional lymph node dissection, implementation of adjuvant chemotherapy, and choice of surgical method were independent predictors of prognosis.

Conclusion

Distant metastasis and regional lymph node dissection are associated with poorer outcomes in TOS, and amputation has no better prognosis than limb salvage surgery. Compared with conventional chemotherapy, neoadjuvant chemotherapy did not significantly improve the prognosis of TOS.

Prognostic significance of modified lung immune prognostic index in osteosarcoma patients

Purpose: Osteosarcoma is the most common primary malignancy of bone with a dismal prognosis for patients with pulmonary metastases. Evaluation of osteosarcoma prognosis would facilitate the prognosis consultation as well as the development of personalized treatment decisions. However, there is limited effective prognostic predictor at present. Lung Immune Prognostic Index (LIPI) is a novel prognostic factor in pulmonary cancers, whereas, the prognostic significance of LIPI in osteosarcoma has not yet been well clarified. In this study, we firstly explore the prognostic role of LIPI and further modify this predictive model in osteosarcoma.

Patients and methods: A retrospectively study was conducted at Musculoskeletal Tumor Center of West China Hospital between January 2016 and January 2021. Hematological factors and clinical features of osteosarcoma patients were collected and analyzed. The area under curve (AUC) and optimal cuff-off of each single hematological factor was calculated.

Results: In this study, lactate dehydrogenase (LDH), derived neurtrophil to lymphocyte ratio (dNLR), and Hydroxybutyrate dehydrogenase (HBDH) have higher AUC values. LIPI was composed of LDH and dNLR and was further modified by combing the HBDH, forming the osteosarcoma immune prognostic index (OIPI). OIPI divided 223 osteosarcoma patients divided into four groups, none, light, moderate, and severe (p < 0.0001). OIPI has a higher AUC value than LIPI and other hematological indexes in t-ROC curve. According to the univariate and multivariate analysis, pathological fracture, metastasis, NLR, platelet–lymphocyte ratio (PLR), and OIPI were associated with the prognosis; and metastasis and OIPI were independent prognostic factors of osteosarcoma patients. An OIPI-based nomogram was also established and could predict the 3-year and 5-year overall survival. In addition, OIPI was also revealed correlated with metastasis and pathological fracture in osteosarcoma.

Conclusion: This study first explore the prognostic significance of LIPI in osteosarcoma patients. In addition, we developed a modified LIPI, the OIPI, for osteosarcoma patients. Both the LIPI and OIPI could predict the overall survival of osteosarcoma patients well, while OIPI may be more suitable for osteosarcoma patients. In particular, OIPI may have the ability to identify some high-risk patients from clinically low-risk patients.

Primary Aneurysmal Bone Cyst of Nasal Cavity and Sinuses in a Child: Case Report and Literature Review

INTRODUCTION

Aneurysmal bone cysts (ABCs) are a rare benign bone lesion, which are divided into primary and secondary categories, and occur mainly in the vertebra and the long tubular bones. Primary ABCs in the nasal cavity and the sinuses are rare.

CASE PRESENTATION

We reported on a one-year-old boy who suffered from progressive nasal obstruction and intermittent nosebleeds over a period of approximately 1 month. The patient had no history of trauma or surgery. Physical examination showed a red tumor in his right nasal cavity. A magnetic resonance imaging scan showed a multicystic lesion arising from the ethmoid sinus. The lesion was resected under a nasal endoscope without any complications. Histological evaluation confirmed that the lesion was an aneurysmal bone cyst. Because an osteoma was found during the surgery on the cyst, the lesion was considered secondary clinically. However, fluorescence in situ hybridization testing showed a rearrangement of the USP6 (ubiquitin-specific protease 6) oncogene on chromosome 17. No recurrence was observed after 1 year.

CONCLUSION

An ABC of the nasal cavity and sinuses in such a young child is very rare and needs to be further analyzed according to postoperative pathology and combined with a genetic examination to make a diagnosis. Endoscopic sinus surgery is an effective method of treatment for this kind of disease.

Pediatric Osteosarcoma: Pearls and Pitfalls

Osteosarcoma is a malignant bone tumor most commonly presenting in children. It has a bimodal distribution with a peak incidence occurring during the ages of 10-14 years old and in adults greater than age 65. The first peak of osteosarcoma correlates with the increased proliferation of bone during the pubertal growth period. Osteosarcoma most frequently presents with localized bone pain, swelling, and an antalgic gait. The patient may attribute symptoms to trauma or strenuous exercise, causing the patient to be managed conservatively. In these cases, the pain persists and eventually leads to further evaluation. The most common type of osteosarcoma is the conventional high-grade osteosarcoma. For conventional osteosarcoma, the diagnosis is typically made or strongly suggested based upon the initial radiographic appearance. Other types of osteosarcomas include low grade central, telangiectatic, small-cell, surface and intracortical. Consequently, it is important for radiologists to be aware of these subtypes and the imaging features that differentiate them from other etiologies to prevent a delay in treatment.

A Case of Telangiectatic Osteosarcoma in the Frontal Bone

Telangiectatic osteosarcoma (TOS) is a subtype of osteosarcoma. TOS in the elderly and TOS in the skull are very rare. Here, we report a case of TOS in the frontal bone of an elderly patient. The patient was a 79-year-old woman who was identified as having a right frontal bone lesion. The patient was initially diagnosed with an intradiploic epidermoid cyst (IEC). A 60mm cystic lesion with bone destruction appeared 5 years later, which enlarged over 2 months. The fluid in the cyst seemed to be blood that had lost its clotting ability. Tumor and the surrounding tissue were resected. The postoperative course was favorable. Postoperative magnetic resonance imaging (MRI) showed no evidence of residual lesions. There was no metastases. Histopathologically, the cyst wall was composed of fibrous connective tissue and did not contain epithelial components. There were no skin appendages and keratinized tissues in the lesion. Based on these findings, the diagnosis changed to aneurysmal bone cyst (ABC). Subsequent immunohistochemical examinations confirmed that the MIB-1 index was 50% in some sections and there were atypical cells showing osteogenic properties in other sections. Based on these results, the patient was finally diagnosed with TOS. The differential diagnoses for cystic lesion presenting bone destruction include TOS, ABC, and IEC. In case of cystic lesion with bone destruction, early diagnosis based on histopathological study is important and complete resection with surrounding tissues is required, given the possibility of TOS.

Update on aneurysmal bone cyst: pathophysiology, histology, imaging and treatment

Aneurysmal bone cyst (ABC) is a benign but locally aggressive lesion that predominantly affects children and young adults. ABC, which accounts for approximately 70% of the cases, is now recognized to be a true neoplasm, whereas ABC-like changes associated to other bone neoplasms (also referred in the literature as secondary ABC) accounts for the remaining 30%. The solid variant of ABC is also considered a true neoplasm but is rare. ABC can involve any bone in the body, and although it has a metaphyseal preference, it can involve any part of a bone and soft tissues. As with any bone tumor, the initial evaluation of ABCs should be done with radiographs followed by magnetic resonance imaging or less frequently computed tomography for further characterization. The imaging appearance of ABC is variable; however, a lytic and expansile lesion with fluid-fluid levels is the most common presentation. The main differential diagnosis of an ABC in the pediatric population is unicameral bone cyst (UBC) and telangiectatic osteosarcoma, therefore a biopsy is recommended before treatment. The therapeutic options of ABC range from curettage with or without adjuncts such as phenol, liquid nitrogen, argon laser and bone grafting or bone substitutes to more recently employed alternatives such as image-guided sclerotherapy with various sclerosing agents and monoclonal antibodies (e.g., Denosumab).

Characteristics and prognosis of telangiectatic osteosarcoma: a population-based study using the Surveillance, Epidemiology and End Results (SEER) database

Background

Telangiectatic osteosarcoma (TOS) is a rare type of osteosarcoma for which limited clinical data is available. Furthermore, the clinical characteristics and prognosis of TOS remain unclear.

Methods

A large population-based cohort analysis was conducted using the Surveillance, Epidemiology and End Results (SEER) registry. The data of TOS and conventional osteosarcoma (COS) patients from 2000 to 2017 were collected. The categorical variables were assessed by Chi-squared tests. Kaplan-Meier curves and log-rank (Mantel-Cox) tests were used to examine the survival outcomes between the groups. Cox proportional hazard models were used for univariate and multivariate analyses of TOS patient survival-related variables.

Results

A total of 141 TOS patients and 2961 COS patients were included in this analysis, and the mean age at diagnosis was 23.5 and 29.4 years, respectively. Compared to COS patients, TOS patients were more likely to be under 20 years old (61.7% vs. 51.7%, P=0.022), and without a second peak of incidence after 60 years of age. The median overall survival (mOS) of TOS patients was not reached compared to a median survival of 84 months for COS patients (hazard ratio 0.75, 95% confidence interval 0.59 to 0.95, P=0.0175). After adjusting these data for age at diagnosis, stage, and surgery at the primary site, no significant differences in mOS were observed between the two groups. In univariate analyses, being under 20 years of age, having localized or regional stage disease, and having undergone surgery were associated with a decreased risk of death. Subsequent multivariate analysis indicated that age at diagnosis, stage, and surgery at the primary site were all independent predictors of prognosis in TOS patients.

Conclusions

Patients with TOS were younger than patients with COS and did not show a second peak after 60 years of age. Age, summary stage at diagnosis, and surgery at the primary site were independent predictors of survival for TOS patients.

Osteoid Tumors of Bone

We present a review of several bone (osteoid)-forming tumors including enostosis, osteoid osteoma, osteoblastoma, and osteosarcoma. These entities were chosen because they are reasonably common-neither seen every day nor rare. When applicable, recent information about the lesions is included.

Fluid-fluid Levels in Musculoskeletal Tumor Imaging

Fluid-fluid levels result from the separation of two fluids of differing densities within a cavernous space with the boundary between the two layers running in a horizontal plane at 90 degrees to the direction of gravity. Magnetic resonance imaging is the most sensitive imaging modality to identify fluid-fluid levels. Although the most common bone lesions containing fluid-fluid levels are aneurysmal bone cyst and telangiectatic osteosarcoma, fluid-fluid levels can be observed in a wide variety of bone and soft tissue lesions. Therefore, fluid-fluid levels cannot be considered diagnostic of any particular type of tumor and the diagnosis should be made on the basis of other clinical, radiological and pathological findings. This article summarizes the pathophysiology and imaging characteristics of fluid-fluid levels and discusses the differential diagnosis of tumors with this imaging sign.

Paediatric bone lesions: diagnostic accuracy of imaging correlation and CT-guided needle biopsy for differentiating benign from malignant lesions

OBJECTIVE

To determine the sensitivity, specificity and accuracy of CT-guided needle biopsy (CT-NB) for distinguishing benign and malignant lesions in children with suspected primary bone tumours, and to assess the correlation between imaging diagnosis and final diagnosis.

METHODS

Retrospective review of children who underwent CT-NB of a suspected primary bone tumour between October 2016 and October 2019. Data collected included anatomical location, imaging diagnosis, type of needle, type of biopsy sample, CT-NB diagnosis, final diagnosis and post-procedural complications. The final diagnosis was established based on surgical histology or clinical/imaging follow-up.

RESULTS

125 patients met the inclusion criteria (68M, 57F: mean age 11 years; range 10 months-18 years). Biopsy was performed using a 10 cm Jamshidi needle (10G n = 96; 13 G n = 8); 14G Tru-Cut needle (n = 18); 14G Temno needle (n = 3). The commonest anatomical locations were the femur (n = 40), tibia (n = 25) and humerus (n = 16), while the commonest diagnoses were osteosarcoma (n = 35), CRMO (n = 15) and LCH (n = 14). A benign tumour was correctly identified on imaging in 100% of cases, and a malignant tumour in 95.8%. Sensitivity, specificity and diagnostic accuracy of CT-NB for distinguishing malignant from benign lesions were 98%, 100 and 99%. Of 24 indeterminate biopsy results, all that had a non-aggressive radiological appearance were benign. No immediate complications were recorded.

CONCLUSION

CT-NB represents a safe and very effective tool for differentiating benign and malignant lesions in children presenting with a suspected primary bone tumour. Suspected radiological diagnosis plays a pivotal role in the management of indeterminate biopsy results.

ADVANCES IN KNOWLEDGE

Paediatric bone tumours pose a significant diagnostic and therapeutic challenge. The interpretation of the imaging findings is essential for the successful management of indeterminate histological results.

The differentiation between aneurysmal bone cyst and telangiectatic osteosarcoma: a clinical, radiographic and MRI study

OBJECTIVES

Aneurysmal bone cyst (ABC) and telangiectatic osteosarcoma (TOS) share several clinical and imaging features, including young presentation, long bone involvement, lytic appearance on radiography and fluid-fluid levels on MRI. Therefore, they may be difficult to differentiate. The aim of this study is to identify clinical, radiological and MRI features which aid differentiation of the two lesions.

MATERIALS AND METHODS

Retrospective review of all histologically confirmed ABC and TOS over an 11-year period. Data recorded include age at presentation, sex, skeletal location and various radiographic and MRI features.

RESULTS

This retrospective study included 183 patients, 92 males and 91 females. Mean age at presentation of 18.4 years (range 1-70 years); 152 cases of ABC and 31 TOS. No significant difference between age and sex. TOS was significantly less likely to involve the axial skeleton; no difference related to location within the bone. Radiographic findings significantly favouring ABC included a less aggressive pattern of bone destruction, a purely lytic appearance, an expanded but intact cortex, no periosteal response and no soft tissue mass. MRI features significantly favouring ABC included smaller tumour size (maximum mean dimension 46 mm compared to 95 mm for TOS), absence of soft tissue mass, > 2/3 of the lesion filled with fluid levels and thin septal enhancement following contrast.

CONCLUSIONS

Several radiographic and MRI features aid in the differentiation between ABC and TOS. Lesions with a geographic Type 1A or IB pattern of bone destruction which are completely filled with FFLs on MRI can confidently be diagnosed as ABC.

The potential of micelleplexes as a therapeutic strategy for osteosarcoma disease

Osteosarcoma (OS) is a rare aggressive bone, presenting low patient survival rate, high metastasis and relapse occurrence, mostly due to multi-drug resistant cells. To surpass that, the use of nanomedicine for the targeted delivery of genetic material, drugs or both have been extensively researched. In this review, we address the current situation of the disorder and some gene therapy options in the nanomedicine field that have been investigated. Among them, polymeric micelles (PM) are an advantageous therapeutic alternative highly explored for OS, as they allow for the targeted transportation of poorly water-soluble drugs to cancer cells. In addition, micelleplexes are PMs with cationic properties with promising features, such as the possibility for a dual therapy, which have made them an attractive research subject. The aim of this review article is to elucidate the application of a micelleplex formulation encapsulating the underexpressed miRNA145 to achieve an active targeting to OS cells and overcome multi-drug resistance, as a new and viable therapeutic strategy.