Microwave Ablation for Osteoid Osteoma in a Young Patient: A Case Report.

Osteoid osteoma (OO) is a common benign ossifying lesion that is most prevalent among youth. Usually, it attacks the diaphyseal or metaphyseal bones that are tubular. The common hallmark of muscle pain is the reported occurrence of night pain that is nearly always present, yields satisfactory responses from nonsteroidal anti-inflammatory medications, and may be joined by complaints regarding physical activities. Also, it shows typical signs of study procedures like computed tomography (CT) and magnetic resonance imaging (MRI). A nidus, which is the primary marker in the diagnostic formation of shadowed images, is a crucial sign of an OO. This source is usually portrayed as an oval lytic lesion, measuring 1 cm flat and surrounded by a region of reactive ossification. It is laborious to diagnose OO since the condition is frequently confused with many other ones, and testing and therapy may be delayed and complicated as a result. There are still few studies on OO diagnosis and distinguishing of surrogate conditions. Unfortunately, either ablation or resection can be said to be the cure. Improved detection of OO shows the possibility for prompt diagnosis, fewer patient discomfort and side effects, less cost involved in unnecessary treatments, and a rightly diagnosed condition.

A comprehensive MRI analysis of osteoid osteomas in patients with diverse radiological features across various regions.

BACKGROUND: Magnetic resonance imaging (MRI), which does not involve ionizing radiation, is the preferred imaging modality for diagnosing osteoid osteoma (OO), an ailment more common in children and young adults. PURPOSE: This study aims to perform a literature review and delineate the MRI findings of OO lesions in patients exhibiting varying radiological features across different regions. MATERIALS AND METHODS: A retrospective study included 63 patients diagnosed with OO through MRI, assessed independently by two blinded radiologists using both standard and dynamic contrast-enhanced MRI techniques. After excluding 7 patients with prior biopsy, surgery, or RFA, the study included 56 patients with 57 lesions. RESULTS: Of 57 lesions evaluated, 50 were in long, and 7 in flat bones. One patient presented with two separate nidi within the intertrochanteric region. Most of the lesions, 49 (86%), were extra-articular, while 8 (14%) were intra-articular. The nidus was intracortical in 45 (78.9%) patients, intramedullary in 5 (8.8%), subperiosteal in 5 (8.8%), and endosteal in 2 (3.5%). Average nidus diameter was 7.02 ± 2.64 mm (3-12.6 mm). Central nidal calcification was present in 68.4% (n = 39) cases. Contrast enhancement was intense at 90.5%, moderate at 9.5%. Reactive sclerosis around the nidus was severe (50.9%), moderate (22.8%), and mild (26.3%). Bone marrow edema was severe (70.2%), moderate (14.0%), and mild (15.8%). Soft tissue edema was identified in 77.2% of all lesions. CONCLUSION: To minimize delays in diagnosis and treatment, radiologists should become acquainted with the typical OO MRI findings and the atypical MRI findings that might be mistaken for other conditions.

Telangiectatic osteosarcoma of the mandible-A rare case report and an insight into differential diagnosis.

Telangiectatic osteosarcoma (TOS) is a rare variant of osteosarcoma that typically affects young individuals and long bones. The case under discussion was seen in the mandible of a 57-year-old female and had rapidly grown in size within a week. Microscopically, the tumour was characterised by large vascular cavities surrounded by anaplastic cells. Thin lacy tumour osteoid was observed at various foci. Abundant multinucleated osteoclastic giant cells along with areas of necrosis were also noted. The tumour cells were positive for SATB2, while negative for Cytokeratin AE1/3, CD 34. Ki-67 positivity was observed in more than 50% of tumour cells. A diagnosis of high grade telangiectatic osteosarcoma was thus made.

Recurrent and transformation of borderline to malignant phyllodes tumour with osteoid differentiation: a case report and literature review.

Phyllodes tumours or cystosarcoma phyllodes are fibroepithelial tumours of the breast and represent 1% of breast tumours. A 20-year-old nullipara presented with an enlarging left breast mass over 6 months. Although widely excised, it was reported to be a 12 × 10 × 5.5-cm borderline phyllodes tumour with involvement of the superior and inferior margins. Seven months later, she presented with a new ipsilateral breast lump measuring 8.5 × 7.5 × 4.6 cm. She underwent a left mastectomy, a three-rib resection with titanic rods for the thoracic cage reconstruction, and a latissimus dorsi flap wound closure. Histopathology revealed a high-grade malignant phyllodes tumour with features of osteoid differentiation with the nearest deep margin measuring 3 mm. She developed metastasis to the ipsilateral axillary lymph nodes and contralateral lung 2 months postoperatively. She was given palliative radiotherapy 60 Gy in 30 fractions to the left axilla. She developed sudden lower-limb weakness due to spinal metastases. The symptoms resolved with radiotherapy to the thoracic spine (T4-T8). As the lesion continued to grow rapidly from the anterior chest wall encircling towards the back, it was deemed unresectable. She was given palliative chemotherapy (doxorubicin six cycles, followed by ifosfamide one cycle) but had disease progression. She passed away 3 months later. The mainstay of treatment for phyllodes tumour is excision with a minimal margin of 1 cm. Although margins were involved after the first surgery, she was followed up as the pathology was a borderline phyllodes. When the lump recurred and had transformed, despite extensive surgery, it returned shortly and progressed. A borderline phyllodes should be excised to obtain a minimal margin of 1 cm, even if it means performing a mastectomy, to minimise recurrence. A recurrence may undergo malignant transformation which is largely chemotherapy and radiotherapy resistant. This will result in a poor outcome and decreased survival.

Stromal osseous metaplasia in urothelial carcinoma of the bladder: An unusual and challenging feature. A case report / Carcinoma urotelial de vejiga con metaplasia ósea estromal: una característica inusual y desafiante. Presentación de un caso

A 62-year-old male presented with pain and haematuria starting 3 months before. The computed tomography showed focal and mural bladder thickening with ureteropelvic dilatation. The following transurethral bladder resection revealed a high-grade muscle-invasive urothelial carcinoma. In the subsequent cystoprostatectomy we found the same tumour, but adding focal tumour-associated stromal osseous metaplasia. Ossifying metaplasia is an extremely rare feature in urothelial carcinoma, with a few reported cases and represents a diagnostic challenge, mimicking radiotherapy-induced sarcoma or sarcomatoid carcinoma. (AU)

Varón de 62 años que consulta por dolor y hematuria desde hace 3 meses. En la tomografía computarizada se observó un engrosamiento focal y mural de la vejiga con dilatación ureteropélvica. La resección vesical transuretral reveló un carcinoma urotelial infiltrante de alto grado músculo-invasivo. En la cistoprostatectomía posterior encontramos el mismo tumor, pero añadiendo focos de metaplasia ósea estromal asociada al tumor. La metaplasia osificante es una característica extremadamente rara en el carcinoma urotelial, con algunos casos informados, y representa un desafío diagnóstico, ya que simula un sarcoma inducido por radioterapia o un carcinoma sarcomatoide. (AU)

Radiofrequency ablation of osteoid osteoma at the base of the coracoid process: Report of two cases.

If you encounter an unexplained case of bone marrow edema in a young patient, consider the possibility of osteoid osteoma (OO). Even in the presence of a nidus near vital structures, RFA can safely be used to treat OO.

[Percutaneous radiofrequency ablation of osteoid osteoma: results from 9 years of experience in a third-level center.] / Ablación percutánea por radiofrecuencia de osteoma osteoide: resultados en 9 años de experiencia en un centro de tercer nivel.

Introduction: Osteoid osteoma is a benign bone tumor that accounts for roughly 2-3% of primary bone tumors and up to 10-12% of benigns bone neoplasms. It is most commonly seen in young adults, and shows male predominance. Over the last years, minimally invasive thermal ablation techniques such as radiofrequency ablation have gained popularity over classical surgery. In this study we evaluate results and complications of CT guided osteoid osteoma radiofrequency ablation. Materials and methods: In this retrospective cohort study all patients that were diagnosed with osteoid osteoma and treated using radiofrequency ablation between January 2014 and December 2022 were included. Pain was assessed using Visual Analog Scale (VAS) pre and post procedure. Technical success was established as positioning of the radiofrequency electrode in the nidus. Primary clinical success was defined as absence of pain after one radiofrequency session. All patients that required a second radiofrequency ablation were included in the overall clinical success group. Results: During the studied period, 61 osteoid osteoma radiofrequency ablations were performed. Fiftyseven of them were included in this study, 32 were men and 25 female. Pre procedure median pain was 9 according to VAS score. Only 23 patients were treated as outpatient, the rest stayed in hospital for 24 hours. Median follow up time was 21,7 months (SD 8,3). Biopsy was performed in 52 patients. Technical success was accomplished in 57 patients (100%). Primary clinical success was 80,7% (46 patients). Those who continued with pain or had recurrence after a symptoms free period (11 patients), were treated with a second radiofrequency ablation, achieving an overall success rate of 94,7%. Only one patient suffered a minor complication (1,7%). Conclusion: CT guided osteoid osteoma radiofrequency ablation is a safe, effective and low complication rate procedure, that can be performed on an outpatient basis. We believe it should be considered as a first line treatment option for osteoid osteoma.

Introducción: El osteoma osteoide es un tumor óseo benigno, que representa el 2-3% de las neoplasias óseas primarias y hasta el 10-12% de los tumores óseos benignos. Tiene mayor incidencia en adultos jóvenes, con predominancia masculina. En los últimos años las técnicas de termoablación mínimamente invasivas han sido utilizadas para el tratamiento del osteoma osteoide, como alternativa a la cirugía clásica. En este estudio evaluaremos los resultados y complicaciones de ablación por radiofrecuencia de osteoma osteoide. Materiales y métodos: Se analizó una cohorte de pacientes en forma retrospectiva con diagnóstico de osteoma osteoide tratados con radiofrecuencia en el Hospital Italiano de Buenos Aires desde Enero del año 2014 hasta Diciembre del año 2022. Todos los pacientes fueron evaluados con la Escala Visual Analógica del dolor (EVA) pre y post procedimiento. El éxito técnico del procedimiento fue considerado como el correcto posicionamiento del electrodo de radiofrecuencia en el nido de la lesión, y el éxito clínico primario como ausencia de dolor post procedimiento. Mientras que los pacientes que requirieron de una segunda sesión de radiofrecuencia para controlar los síntomas serán incluidos como éxito clínico secundario. Resultados: Durante el período mencionado se realizaron 61 ablaciones percutáneas de osteoma osteoide. Se incluyeron en el análisis 57 pacientes, 32 fueron hombres y 25 mujeres. La media de dolor medido por EVA pre procedimiento fue 9. Del total de los pacientes, 23 fueron tratados de manera ambulatoria, el resto permanecieron internados durante 24hs. El tiempo medio de seguimiento fue de 21,7 meses (DS8,3). Se realizó biopsia de la lesión durante el procedimiento en 52 pacientes. Se logró el éxito técnico en 57 pacientes (100%), de ellos el éxito clínico primario se logró en 46 pacientes (80,7%). Los 11 pacientes que continuaron con dolor o presentaron recurrencia de los síntomas luego de un período asintomáticos fueron tratados con una segunda sesión de radiofrecuencia, logrando un éxito clínico secundario 94,7%. Un solo paciente presentó complicaciones post procedimiento (1,7%), correspondiente a hematoma en la planta del pie. Conclusión: Podemos concluir que la ablación percutánea por radiofrecuencia de OO guiada por tomografía en manos de expertos, es un procedimiento seguro, de alta efectividad y baja tasa de complicaciones que puede realizarse de manera ambulatoria. Por lo que consideramos que debe ser tenida en cuenta como primera elección para el tratamiento de esta patología.

Osteoid osteoma of the hook of hamate: An unusual cause of ulnar side wrist pain.

Ulnar side wrist pain is a complex clinical situation because of the pathologies involving multiple closely located structures on the ulnar side of the wrist. Incidence of osseous lesions leading to ulnar side wrist pain is very rare. The effectiveness of commonly employed Magnetic resonance imaging, for diagnosing the pathology in the ulnar side of the wrist might be limited in diagnosing such osseous lesions and can lead to missed diagnosis. We herein present such a rare case of Osteoid osteoma of the hook of hamate presenting as ulnar side wrist pain. The condition, presented a "diagnostic challenge", where it required Computed Tomography to diagnose and guide for appropriate management.

Interest of targeted computed tomography guided by scintigraphy in the diagnosis of an osteoid osteoma of the talus: A surgical case report.

INTRODUCTION AND IMPORTANCE: Osteoid osteoma is a benign primary bone tumor with a predilection for the long bones and vertebrae, presenting a unique challenge when occurring in rare locations such as the talus, accounting for 5 to 8 % of cases. Early imaging struggles to detect its nidus, leading to diagnostic delays, especially when atypical symptoms and previous trauma complicate clinical presentations. This case report illustrates the diagnostic challenges and emphasizes the importance of targeted computed tomography (CT) guided by scintigraphy in diagnosing osteoid osteoma of the talus. CASE PRESENTATION: A 23-year-old male presented with chronic left ankle pain spanning three years, with a history of previous trauma. Initial evaluations including standard radiology and magnetic resonance imaging (MRI) suggested algodystrophy of the talus and tenosynovitis, but failed to identify the osteoma. Persistent pain led to further investigation with bone scintigraphy, revealing hyperfixation indicative of partial algodystrophy. Targeted CT scans focused on the scintigraphy-identified area ultimately revealed an osteoid osteoma's nidus, enabling successful surgical intervention and symptomatic relief. DISCUSSION: The diagnosis of osteoid osteoma in the talus is frequently delayed due to its atypical presentation and rare occurrence. Traditional imaging techniques may overlook the tumor's nidus, underscoring the necessity for targeted diagnostic approaches. This case demonstrates the value of integrating scintigraphy with targeted CT to enhance early diagnosis and treatment planning, contrasting with the limited diagnostic yield of MRI and underscoring CT's superiority for nidus detection. CONCLUSION: Osteoid osteoma of the talus poses significant diagnostic challenges. This case report highlights the utility of scintigraphy-guided targeted CT in identifying the nidus and facilitating prompt surgical management, advocating for a multidisciplinary approach to atypical ankle pain, especially in patients with a history of trauma.

Osteoid Osteoma of the Talus Mimicking Pigmented Villonodular Synovitis in a 15-Year-Old Male: A Case Report.

Osteoid osteoma is a benign tumor of the bone which tends to occur in diaphysis or metaphysis of the long bones. The lesion is generally intraosseous with vague clinical symptoms, hence given the name "great mimicker". When located subperiosteally and juxtaarticulary, atypical clinical presentation and radiological may lead to a delayed or missed diagnosis. Performing surgery with a misdiagnosis carries the risk of incomplete resection of the lesion and recurrence. We report the case of a 15-year-old male with a subperiosteal osteoid osteoma of the talus, who was misdiagnosed with pigmented villonodular synovitis and operated through anterior ankle arthrotomy. A nodular lesion 1 cm in diameter with hard rubber consistency was removed from the dorsal aspect of the talar neck. The pathological specimens were consistent with subperiosteal osteoid osteoma. The patient's symptoms resolved rapidly in the early postoperative period. The patient remained asymptomatic at the 20th-month follow-up and the control MRI revealed no signs of recurrence. Atypical radiological and clinical presentation of juxtaarticular subperiosteal osteoid osteomas cause misdiagnosis, delay in diagnosis, incomplete resection and recurrence. It is important to keep in mind "juxtaarticular subperiosteal osteoid osteoma" in the differential diagnosis of cases with suspected Pigmented Villonodular Synovitis.

Short- and Long-Term Outcomes after Radiofrequency Ablation of Osteoid Osteomas.

The aim of this study was to evaluate treatment of osteoid osteomas using bipolar radiofrequency ablation (RFA) and patients' quality of life before and after therapy. We retrospectively evaluated patients who underwent bipolar RFA of osteoid osteomas between 2001 and 2016. We assessed patients' symptoms before and after treatment (four weeks after treatment and long-term) using a questionnaire including severity and quality of pain on a 10-point scale (1 = no pain, 10 = severe pain), motion restrictions, pain-related sleep disorders, and necessary pain medication. In addition, we evaluated technical success, complications, hospitalization length, and patients' satisfaction with treatment. This study included 62 patients (43 [69.4%] males, 26.2 ± 13.2 years). Average nidus size was 5.7 ± 2.6 mm. The rate of technical success was 100%. All RFAs were performed without any complications. One patient showed a recurrence, resulting in a recurrence rate of 1.6%, which was successfully treated by another session of RFA. Average hospitalization length was 1.5 ± 0.5 days. A total of 36 patients (58.1%) participated in the questionnaire, reporting an average pain severity of 8.2 ± 1.6 before RFA compared to 3.4 ± 3.0 four weeks after and an average of 2.1 ± 2.3, 6.6 years after therapy, (both p < 0.001). After therapy, 31 (86.1%) patients had no pain. The majority of patients (n = 34, 94.4%) had reduced or absent motion restriction after therapy (p < 0.001). Patient satisfaction rate was 91.7%. In conclusion, bipolar RFA is a safe and effective treatment modality for osteoid osteomas and improves quality of life by reducing pain severity and motion restrictions.

Stromal osseous metaplasia in urothelial carcinoma of the bladder: An unusual and challenging feature. A case report.

A 62-year-old male presented with pain and haematuria starting 3 months before. The computed tomography showed focal and mural bladder thickening with ureteropelvic dilatation. The following transurethral bladder resection revealed a high-grade muscle-invasive urothelial carcinoma. In the subsequent cystoprostatectomy we found the same tumour, but adding focal tumour-associated stromal osseous metaplasia. Ossifying metaplasia is an extremely rare feature in urothelial carcinoma, with a few reported cases and represents a diagnostic challenge, mimicking radiotherapy-induced sarcoma or sarcomatoid carcinoma.

Osteoid osteoma appearing after bony fracture in a girl with osteogenesis imperfecta.

Osteoid osteoma (OO) is a common, benign bone tumor. However, there are no case reports of OO associated with osteogenesis imperfecta (OI), or pathological fractures in OO. A 3-year-old girl with OI sustained a complete right tibial diaphyseal fracture. Bony fusion was completed after 4 months of conservative therapy; nevertheless, 18 months later spontaneous pain appeared at the fracture site, without any cause. Plain radiographs showed a newly apparent, rounded area of translucency 1 cm in diameter, just overlapping the previous fracture. Images obtained using three-dimensional time-resolved contrast-enhanced magnetic resonance angiography showed strong central enhancement in the early phase, with an apparent nidus, suggesting the diagnosis of OO. Nineteen months after the first fracture, while skipping, the patient refractured her tibial diaphysis at the site of the previous fracture. This is a very rare case of OO, apparently co-existing with OI and leading to a bony fracture. In our case, the combination of bone fragility in OI and a recent fracture at the site of the OO may have caused the re-fracture.

Percutaneous CT-Guided Microwave Ablation for the Treatment of Osteoid Osteomas: A Single Center Experience.

RATIONALE AND OBJECTIVES: The aim of the current study was to evaluate the feasibility and effectiveness of CT-guided microwave ablation (MWA) in the treatment of osteoid osteomas (OO). MATERIALS AND METHODS: Data from 59 consecutive patients who underwent percutaneous CT-MWA for OO treatment were examined in the current retrospective study. The period of this study spanned from January 2021 to May 2023 at a single institution. The study involved an evaluation of clinical and radiological characteristics, procedural data, Visual Analog Scale (VAS) pain scores, complication incidences, as well as clinical and technical success rates. Statistical analyses were performed by using the Wilcoxon test with Bonferroni correction, Friedman, Spearman, Mann-Whitney U test. RESULTS: 59 patients with an average age of 17.31 ± 8.53 years underwent CT-guided MWA for the treatment of OO. The procedure demonstrated a high success rate, with 96.6% of cases achieving both technical and clinical success. However, recurrence was observed in two patients (3.4%) at the three-month follow-up. These cases were successfully managed with a second MWA procedure. The median VAS pain scores reported by the patients was significantly improved post-procedure: from 8.64 ± 1.14 before treatment to 0.63 ± 0.98 in the first month, 0.41 ± 1.02 in the third month, and 0.15 ± 0.45 in the sixth month. Only one patient (1.7%) experienced a minor complication; no major complications were recorded in this study. CONCLUSION: CT-guided percutaneous MWA is a minimally invasive and a highly effective and safe approach for the treatment of OO.

Tumors of the Posterior Elements of the Spine in Children-an Overview.

In this narrative review, we aim to describe the clinical features, diagnosis, and management of common primary osseous tumors affecting the posterior elements of the spine in children. We searched PubMed, Mendeley, and Google Scholar using the terms primary osseous tumors of the spine in children, tumors of the posterior elements of the spine, and names of individual tumors. The clinical features, investigations, and treatment modalities were analyzed, and a narrative review of the topic was prepared. We have included 54 studies published in the last 20 years. The majority are isolated reports or case series. Tumors of the posterior elements of the spine are rare. They are common in children and the majority of them are benign. Pain and deformity are common presentations. It is better to perform thorough investigations of children complaining of back pain to rule out primary tumors of the posterior elements of the spine.

A comparative study assessing the efficacy and safety of radiofrequency ablation versus surgical treatment for osteoid osteoma: retrospective analysis in a single institution.

OBJECTIVE: We aim to evaluate the efficacy of CT-guided percutaneous radiofrequency ablation (RFA) and surgical treatment in osteoid osteoma (OO) treated at the Medical University of Graz. MATERIALS AND METHODS: In a single-institution study, we analysed data from January 2005 to January 2021 of patients with histological/radiological diagnosis of OO. CT and MRI scans were reviewed for typical findings. Means (with SD) and medians (with IQR) were reported for normally and non-normally distributed variables. Differences between groups were assessed using chi-squared tests and t-tests. RESULTS: One hundred nineteen patients (mean age: 21.6 ± 10.9 years; 63.9% males) with confirmed OO were retrospectively evaluated. 73 and 43 patients underwent RFA and surgery, respectively. In three cases, RFA combined with surgery was performed. Pre-intervention, 103 patients (88.8%) had undergone CT, and 101 had an MRI (87.1%). The nidus was confirmed in 82.5% of cases with CTs (85/103) and 63.4% with MRIs (64/101). The majority of nidi were located cortically (n = 96; 82.8%), most frequently in the femur (38 patients, 33.3%) with a median size of 8.0 mm (IQR: 5.0-12.0 mm). Median symptom duration before treatment was 6.0 (IQR: 4.0-13.0) months. The complication rate was 12.1% (14/116; 15.1% RFA vs. 7.0% surgery; p = 0.196). In total, 11.2% of patients had persistent symptoms after one week with clinical success rates of RFA and surgery, 86.3% and 90.7% (p = 0.647), respectively. CONCLUSION: Compared to surgical treatment, CT-guided percutaneous RFA is a safe, minimally invasive, reliable, and efficient treatment option for OO. CRITICAL RELEVANCE STATEMENT: This article critically assesses the diagnosis and treatment of osteoid osteoma, emphasising accurate imaging, and detailing a non-invasive option for effective management. KEY POINTS: • This study analyses 116 cases of OO at one institution, focusing on symptom persistence, recurrence in short-term follow-up, and complications in two study groups. • Surgery showed higher, though not statistically significant, success despite comparable symptom persistence; CT displayed typical OO features more than MRI, regardless of the intramedullary, cortical and subperiosteal location as well as the site of the affected bone. • CT-guided RFA is an effective therapeutic alternative for OO compared to surgical intervention. In case of atypical OO appearance, RFA is not the first-line treatment.

Mandibular Osteoblastoma: A Case Report of a Rare Entity.

Osteoblastoma, an uncommon bone neoplasm characterized by the formation of osteoid tissue, constitutes a rare subset of bone tumors, representing only a negligible percentage of cases. While extensive research on the condition has identified a predilection for long bones and vertebrae, occurrences in facial bones are infrequent. This case report discusses a unique presentation in a nine-year-old female diagnosed with a tumor located in the mandibular parasymphysis region. Radiological examination revealed distinctive irregular contours surrounding the lesion, prompting a comprehensive investigation involving biopsy and subsequent histological analysis. The ensuing evaluation definitively confirmed the diagnosis of a typical benign osteoblastoma. This report highlights the novelty of an unresected benign osteoblastoma situated in the mandible, currently undergoing periodic review, with the option of surgery also on the table.

Robot-assisted Percutaneous Radiofrequency Ablation for the Treatment of Osteoid Osteomas.

OBJECTIVE: Percutaneous CT-guided radiofrequency ablation (CT-RFA) is a widely accepted procedure for treatment of osteoid osteomas. However, the application of CT-RFA was restricted as a result of some drawbacks, such as radiation exposure, and inconvenience in general anesthesia. The primary aim of this study is to evaluate the safety and efficacy of intra-operative TiRobot-assisted percutaneous RFA of osteoid osteomas. METHODS: We retrospectively reviewed 21 medical files of patients who were treated with percutaneous RFA of osteoid osteomas guided by the TiRobot system in our institution between March 2021 and April 2022. The three-dimensional images obtained by a 3D C-arm intra-operatively were sent to the TiRobot system. The puncture point and trajectory were designed. Then the guide pin was positioned to the lesion with the assistance of TiRobot and the biopsy sheath was inserted into the lesion through the guide pin. The tumor was biopsied for pathological examination. Then the RFA needle was inserted into the nidus through the biopsy sheath for thermal ablation. Data were extracted on the associated complications, the reduction in pain at 1 month and 1 year postoperatively assessed by the visual analogue scale (VAS). A paired t-test was used to compare the pre-operative and post-operative VAS scores. RESULTS: The patients included 17 males and four females with a mean age of 19.5 ± 10.4 years (range 3-45 years). Lesions were located on the femur in nine cases, on the tibia in nine cases, on the humerus in one case, on the calcaneus in one case, and on the acetabulum in one case. TiRobot-assisted percutaneous RFA was successfully performed on all 21 patients. There was no intra-operative or post-operative complications observed. Pathological diagnosis of osteoid osteoma was obtained in 11 patients, but the other 10 cases were not pathologically diagnosed. The mean follow-up time was 18.8 months (range: 12-26 months).Post-operative VAS scores were reduced significantly in all cases. The mean VAS score decreased from 6.5 pre-operatively to 0.5 at 1 month post-operatively and to 0.1 at 1 year post-operatively. CONCLUSION: As a reliable technique for localizing and resection of nidus, TiRobot-assisted percutaneous RFA is a safe and effective option for the treatment of osteoid osteomas.

Approaching virtual osteoid volume estimation and in-depth tissue characterization in patients with tumor-induced osteomalacia.

Tumor-induced osteomalacia (TIO) poses a significant diagnostic challenge, leading to increased disease duration and patient burden also by missing clinical suspicion. Today, diagnosis of osteomalacia relies on invasive iliac crest biopsy, if needed. Therefore, a noninvasive method would be beneficial for patients with severe osteomalacia, such as TIO, to inform their clinical management and address specific needs, like estimating the regeneration capacity at high osteoid volumes (OVs) or the potential of a hungry bone syndrome after tumor removal. Furthermore, given the lack of comprehensive histological characterization of TIO, there is a need for additional tissue characterization. Therefore, our assessment encompassed iliac crest biopsies that were examined using quantitative electron backscattered microscopy, Raman spectroscopy, micro-computed tomography, and histology to analyze the biopsy tissue. Our clinical assessment encompassed DXA and high-resolution peripheral quantitative computed tomography (HR-pQCT) alongside with biochemical analyses and clinical evaluations. Combining imaging and clinical data, we established a model to predict the OV. We compared 9 TIO patients with 10 osteoporosis (OPO) patients and 10 healthy controls. Histological analyses confirmed a pronounced OV in TIO patients (OPO: 1.20% ± 1.23% vs TIO: 23.55% ± 12.23%, P < .0005), and spectroscopy revealed lower phosphate levels in TIO biopsies. By combining HR-pQCT and laboratory diagnostics, we developed a linear regression model to noninvasively predict the OV revealing significantly higher modeled OV/BVmodel values of 24.46% ± 14.22% for TIO compared to the control group (5.952% ± 3.44%, P ≤ .001). By combining laboratory diagnostics, namely, ALP and Tt.BMDRadius measured by HR-pQCT, we achieved the calculation of the virtual osteoid volume to bone volume ratio (OV/BVmodel) with a significant correlation to histology as well as reliable identification of TIO patients compared to OPO and control. This novel approach is potentially helpful for predicting OV by noninvasive techniques in diagnostic procedures and improving the clinical management of TIO.

Osteomalacia, a bone mineralization disease, results in soft bones due to a lack of calcium or phosphate. Tumor-induced osteomalacia (TIO) is an acquired and challenging form of osteomalacia due to low serum phosphate levels that often lead to prolonged patient suffering. Current diagnosis of osteomalacia involves surgical bone biopsies, but a noninvasive approach would be beneficial, improving clinical management and addressing specific needs like estimating the bone's quality and ability to recover. We used advanced techniques like electron microscopy, spectroscopy, and high-resolution CT to study bone samples from 9 TIO patients. Additionally, we assessed their bone health through sophisticated imaging and blood analyses. Microscopy confirmed huge amounts of soft bone tissue due to a severe mineralization defect. By combining imaging and blood analysis, we developed a noninvasive method to predict the amount of soft tissue (osteoid) to understand soft bones without the need for surgical interventions. In conclusion, our innovative approach, combining blood diagnostics (alkaline phosphatase) with total BMD from high-resolution 3D clinical imaging of the lower arm, allows us to predict the osteoid amount virtually. This method can also compare TIO patients with controls or those with osteoporosis and might be helpful in the future.