Parosteal osteosarcoma with low grade chondrosarcoma and liposarcoma components. A rare histologic variant. Case report and literature review.

INTRODUCTION: conventional parosteal osteosarcoma is an uncommon malignant bone tumor, comprising 4% of all osteosarcomas. Although rare, parosteal osteosarcoma is the most common type of osteosarcoma of the bone surface. We present the clinical, histological and imaging characteristics of a rare histologic variant of a parosteal osteosarcoma, review the literature and emphasize the importance of radio-pathological correlation as well as the interpretation of a representative biopsy in order to obtain the correct diagnosis. CASE REPORT: a 36-year old woman began her condition one year prior to admission to the hospital with increased volume in the left knee and pain. Image studies showed a juxtacortical heterogeneous tumor localized on the posterior surface of the distal femoral metaphysis. An incisional biopsy was performed, with the diagnosis of a Parosteal Osteosarcoma and a wide surgical resection was undertaken. According to the findings of the surgical specimen, the diagnosis of a Parosteal Osteosarcoma with low grade chondrosarcoma and liposarcoma components was made. The knowledge of this rare parosteal osteosarcoma variant can lead the orthopedic oncologists to avoid overlooking the adipose component and provide adequate surgical margins. CONCLUSION: we present the clinical, histological and imaging characteristics of a Parosteal Osteosarcoma with low grade liposarcoma and chondrosarcoma components.

INTRODUCCIÓN: el osteosarcoma parosteal convencional es un tumor óseo maligno poco común, que comprende el 4% de todos los osteosarcomas. Aunque es poco común, el osteosarcoma parosteal es el tipo más común de osteosarcoma de la superficie ósea. Presentamos las características clínicas, histológicas y de imagen de una variante histológica rara de un osteosarcoma parosteal, revisamos la literatura y enfatizamos la importancia de la correlación radio-patológica, así como la interpretación de una biopsia representativa para obtener el diagnóstico correcto. REPORTE DE CASO: mujer de 36 años inició su cuadro un año antes de su ingreso al hospital con aumento de volumen en rodilla izquierda y dolor. Los estudios de imagen mostraron una tumoración heterogénea yuxtacortical localizada en la superficie posterior de la metáfisis femoral distal. Se realizó biopsia incisional, con diagnóstico de osteosarcoma parosteal y se realizó resección quirúrgica amplia. De acuerdo con los hallazgos de la pieza quirúrgica se realizó el diagnóstico de osteosarcoma parosteal con componentes de condrosarcoma y liposarcoma de bajo grado. El conocimiento de esta rara variante de osteosarcoma parosteal puede llevar a los ortopedistas oncólogos a considerar otros componentes y proporcionar márgenes quirúrgicos adecuados. CONCLUSIÓN: presentamos las características clínicas, histológicas y de imagen de un osteosarcoma parosteal con componentes de liposarcoma y condrosarcoma de bajo grado.

Dedifferentiated Primary Parosteal Osteosarcoma of the Temporal Bone in a 19-Year-Old Patient: A Case Report.

Osteosarcoma is the most common primary malignant tumor affecting the bone but is a rare occurrence in the head and neck region. Complete surgical resection with wide surgical margins is currently the main treatment strategy for osteosarcoma but can be hard to achieve due to the complex anatomy of the head and neck. We report the first case of primary high-grade dedifferentiated parosteal osteosarcoma arising from the temporal bone in published literature. The 19-year-old patient presented with a left retroauricular lesion measuring 3 cm in diameter. Radiographic imaging and biopsy suggested the diagnosis of intermediate-grade chondrosarcoma, but definitive histopathology confirmed a diagnosis of dedifferentiated parosteal osteosarcoma. The tumor was resected with wide margins, removing the underlying temporal bone, periosteum and overlying soft tissue through a lateral temporal bone resection. The middle ear was reconstructed with cartilage grafting, and the dura of the posterior and middle cranial fossa was covered using temporal fascia grafts and local transpositional flaps. The patient is recurrence free 10 months after treatment. This report was assembled following CARE [The CARE guidelines (for Case Reports)] guidelines and describes clinical, histological, and radiological manifestations of our patient's rare clinical entity and may provide more data in treating patients with osteosarcoma affecting the anatomically complex head-and-neck region.

Periosteal chondrosarcoma: an unusual juxtacortical sarcoma.

Periosteal chondrosarcoma is a rare tumor. It can be difficult to diagnose radiographically and pathologically and can be confused with periosteal osteosarcoma; however, the treatment of these two lesions is quite different. Increased awareness of imaging features of this lesion, particularly those that can help differentiate it from other surface-based tumors, can help one recognize this entity. We report the case of a periosteal chondrosarcoma in a young woman, highlighting the diagnostic imaging features of this disease, and her treatment with a joint-sparing geometric resection of the distal femur, using patient-specific 3D-printed cutting guides and matched allograft reconstruction.

[Parosteal osteosarcoma of the femur and salvage surgery with intercalary prosthesis. Experience in a third level unit and surgical technique]. / Osteosarcoma parostal de fémur y cirugía de salvamento con prótesis intercalar. Experiencia en una unidad de tercer nivel y técnica quirúrgica.

INTRODUCTION: parosteal osteosarcoma is an extramedullary malignant bone tumor in which cells produce osteoid, represents less than 5% of all osteosarcomas, it occurs predominantly in women between the second and fourth decade of life. It is often located in the distal region of the femur and proximal tibia. Clinically it presents with increased volume and thigh or knee pain. Due to its low incidence and clinical features, a clinical case of femoral parosteal osteosarcoma is presented, with description of the surgical technique performed. CASE REPORT: a 14-year-old female presented with a 6-month history of increased volume and right thigh pain. Radiological studies revealed a bone lesion with malignant characteristics, for which she was sent to third-level hospital where oncology study protocol was set up; consisting in two percutaneous biopsies of the lesion with Jamshidi needle, which were histopathology reported as negative for malignant cells. The pulmonary high-resolution computed tomography showed metastasis and a Tc-99m MDP bone scintigraphy showed increased osteoblastic activity in the right femoral shaft. Given the results, is confirmed the need of en-bloc resection and intercalary prosthesis implantation with adjuvant chemotherapy. CONCLUSION: the intercalary prosthesis is a suitable therapeutic option in limb-salvage surgery for patients with femoral parosteal osteosarcoma.

INTRODUCCIÓN: el osteosarcoma parostal es un tumor óseo maligno extramedular en el cual las células tumorales producen osteoide. Representa menos de 5% de los osteosarcomas. Se presenta predominantemente en la mujer, entre la segunda y cuarta década de la vida. Su localización más frecuente es la región distal del fémur y proximal de la tibia. Clínicamente, se manifiesta con aumento de volumen y dolor en muslo o rodilla. Debido a su baja incidencia y características clínicas, se presenta un caso clínico de osteosarcoma parostal femoral con descripción de la técnica quirúrgica realizada. CASO CLÍNICO: femenino de 14 años edad con cuadro clínico caracterizado por aumento de volumen y dolor en muslo derecho de seis meses de evolución. Se realizaron radiografías de fémur derecho, encontrando lesión ósea con características compatibles de malignidad, por lo que es enviada a unidad de tercer nivel para iniciar protocolo oncológico; se realizan dos biopsias percutáneas con aguja de Jamshidi, ambas con reporte histológico negativo para células malignas. En tomografía pulmonar de alta resolución se observó presencia de metástasis y la gammagrafía ósea con Tc99 reportó actividad osteoblástica en fémur derecho. Se decide tratamiento con resección en bloque y colocación de prótesis intercalar más quimioterapia adyuvante. CONCLUSIÓN: la prótesis intercalar resulta una opción terapéutica adecuada en la cirugía de salvamento de extremidad para pacientes con diagnóstico de osteosarcoma parostal femoral.

Does the adherence of distal femur parosteal osteosarcoma to the neurovascular bundle increase the rate of local recurrences?

BACKGROUND: Proximity of tumor to the neurovascular bundle (NVB) makes achieving a wide margin difficult. In low-grade parosteal osteosarcoma (POS), it is not clear whether adherence of tumor to NVB increases the rate of local recurrence (LR). In this study, we evaluated whether tumor adherence to the NVB increases the risk of LR in low-grade POS of the distal femur? HYPOTHESIS: We hypothesized that if the thin neurovascular barrier (the adventitia of the vessels and the epineurium of the nerve) prevents tumor penetration, the rate of LR should be comparable between the lesions with and without a continuous layer of healthy fatty tissue between the tumor and NVB. MATERIALS AND METHODS: In a retrospective survey, 30 patients with low-grade POS of the posterior aspect of the distal femur were evaluated for the proximity of mass to NVB. Based on the proximal to distal T1 axial MRI sections, the tumors were divided into two groups including the tumors with an uninterrupted (group A) and interrupted (group B) rim of fatty tissue between the mass and NVB. The rate of LR was compared between the two study groups. The concordance of MRI in detecting NVB adherence was checked with pathology specimen. RESULTS: Using MRI, we identified 16 cases in group A and 14 cases in group B. The MRI status of fatty rim was concordant with pathology specimen in 96.4% of cases. The mean follow-up period of the two groups was not statistically different (117±27.6 vs. 105.8±29.4 months, respectively, p=0.29). The other baseline characteristics of the two groups were statistically comparable, as well. The rate of LR was 12.5% (2 out of 16 patients) in group A and 14.3% (2 out of 14 patients) in group B (95% CI: 0.142-9.586, p=0.87). The 10-year recurrence-free survival was 87.5% for group A and 85.7% for group B (p=0.9). DISCUSSION: The absence of a continuous rim of fatty tissue between the tumor and NVB in MRI does not increase the risk of LR in low-grade POS of the distal femur. LEVEL OF EVIDENCE: IV.

Parosteal osteosarcoma of the thumb: A case report and literature review.

Parosteal osteosarcoma (PO) is a rare malignant tumor arising from the surface of the bone. Locations in the hand are even more exceptional. This low-grade osteosarcoma shows non-specific clinical and radiological presentation, making diagnosis challenging. Moreover, histologic examination is extremely difficult and can easily lead to misdiagnosis. We report the case of a 21-year-old woman who presented PO of the right thumb, initially diagnosed as a "benign exostosis" 9 years previously. En-bloc resection followed by reconstruction using a free corticocancellous iliac crest autograft provided good esthetic and functional outcome. No recurrence occurred at 2 years' follow-up. Our literature review confirmed the rarity of PO of the hand, with only 8 cases reported in the past 60 years. Amputation was the main treatment, but some authors reported limb-sparing surgery. The present result and those in the literature review support conservative surgery when feasible, with little recurrence and better functional and esthetic results. These rare tumors should not be misdiagnosed, and should be treated in specialized centers to optimize outcome.

Parosteal osteosarcoma of the mandible in a pediatric patient.

Gnathic osteosarcoma is a rare malignant mesenchymal neoplasm showing evidence of osteoid matrix formation. Clinical behaviour and radiological appearances overlap with benign osseous lesions and are prone to misdiagnosis. Early diagnosis of osteosarcoma plays a crucial role in the treatment plan and prognosis. Herein a rare case of parosteal osteosarcoma of fibroblastic histologic subtype affecting the angle of the mandible in a 12-year-old female is presented.

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

OBJECTIVE: To determine the value of chest and skeletal staging in patients with parosteal osteosarcoma (POS), and the incidence of late local and chest recurrence. MATERIALS AND METHODS: Retrospective review of patients across two institutions with histological confirmation of POS diagnosed between January 2007 and March 2020. Data collected included age, sex, skeletal location, results of chest CT and whole-body bone scintigraphy (WB-BSc) or whole-body MRI (WB-MRI) obtained at initial diagnosis. The histological tumour grade based on surgical resection specimens was classified as low-grade POS (LG-POS) and dedifferentiated POS (DD-POS). Findings of chest CT and skeletal staging were correlated with tumour grade. Follow-up chest CT and MRI studies were reviewed to determine the rate of late lung metastases and local recurrence. RESULTS: There were 27 males and 44 females, mean age 33 years (range 12-79 years). The femur (n = 43) and tibia (n = 14) were the most commonly involved bones. From surgical resection histology, 42 (59.2%) were LG-POS and 29 (40.8%) were DD-POS. WB-BSc/WB-MRI showed no skeletal metastases, while 1 case of DD-POS presented with bilateral calcified lung metastases. At follow-up, 7 patients (9.9%) developed lung metastases (mean of 18.9 months, range 10-48 months) from initial presentation, of which all were DD-POS. All but 1 patient who developed subsequent lung metastases had a local recurrence. CONCLUSIONS: Skeletal staging is unlikely to be of value in POS. Staging chest CT is very unlikely to demonstrate lung metastases in LG-POS and could be limited to DD-POS, particularly at the time of local recurrence.

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

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

Characterization and Management of Juxtaglomerular Cell Tumor: Analysis of 9 Cases and Literature Review

Aims: Juxtaglomerular cell tumor is a rare kidney tumor. This study aimed to report the clinic features of juxtaglomerular cell tumor and our treatment experience. Methods: The medical records of 9 juxtaglomerular cell tumor patients treated in our hospital from 1997 to 2017 were retrospectively reviewed. Clinical characteristics, immunohistochemical findings, treatments and outcomes were collected. Results: The mean age of 9 patients was 24±8.1 years (range: 18-37). All cases had symptoms of hypertension, hyperaldosteronism, high plasma renin, high plasma angiotensin II. Four cases had hypokalemia. The renal masses were found by enhanced contrast tomography in all patients. One case received ultrasound-guided ablation and was clinically diagnosed with juxtaglomerular cell tumor. Among the remaining 8 cases, 2 cases received nephrectomy while 6 underwent partial nephrectomy. The 8 cases were pathologically diagnosed with juxtaglomerular cell tumor. Immunohistochemical findings showed that juxtaglomerular cell tumor was positive for vimentin, CD34, and actin but negative for chromogranin A. After treatment, all the patients had normal levels of blood pressure, serum renin activity, potassium, and aldosterone. No patients had tumor progress or metastasis within a median follow-up period of 94 (range: 33-241) months. Conclusion: Hypertension combined with hyperaldosteronism and hypokalemia secondary to high plasma renin activity are the typical symptoms of juxtaglomerular cell tumor. Partial nephrectomy is an optimal treatment for juxtaglomerular cell tumor.

[Parosteal low-grade osteosarcoma with focal differentiation]. / Parossales Low-grade-Osteosarkom mit fokaler Dedifferenzierung.

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

Parosteal Osteosarcoma of the Proximal Phalanx of a Finger.

Osteogenic sarcoma of the hand is very rare and fewer than 50 cases have been reported. There are only 2 previously reported cases of parosteal osteosarcoma involving the phalanges. We report a primary parosteal osteosarcoma involving the proximal phalanx of the right middle finger in a 20-year-old woman, which was managed by ray amputation. There was no evidence of local recurrence or systemic metastasis in the postoperative follow-up period of 2 years.

Gene amplification and tumor grading in parosteal osteosarcoma.

BACKGROUND: Parosteal osteosarcoma (POS) is a unique low grade osteosarcoma. Two separate oncogenes, MDM2 and CDK4, are specifically amplified in POS. Its clinical behavior is usually indolent. In some occasions, it may progress to high grade and become fatal. Malignant transformation with high grade differentiation is the most reliable indicator to predict its aggressiveness and metastatic potential. This study is to discover the relationship between gene amplification and grading. METHODS: Retrospective analysis of MDM2/CDK4 expression/amplification using immunostaining, multiplex quantitative polymerase chain reaction (MQPCR) and fluorescence in situ hybridization (FISH) were studied on 14 patients with recurrent POS. RESULTS: Forty tumor specimens in formalin-fixed paraffin-embedded blocks from 14 patients of POS were included in this study. Twenty-seven tumors are low-grade, 13 are high-grade. All POS showed increased expression of both MDM2 and CDK4 proteins, but not those from conventional osteosarcoma. Except some tumors were non-informative (poor DNA quality), the rest of POS had a marked increase of MDM2 and CDK4 genes copies by MQPCR, and confirmed by MDM2 FISH. Moreover, the folds of amplification increase as tumors progress. And, the amplification folds in high-grade POS are consistently higher than those of conventional ones. CONCLUSION: FISH and MQPCR are both useful assays for estimating oncogene amplification status in bone tumors. Amplification levels of MDM2 and CDK4 are related to tumor grading and progression. Molecular determination of gene amplification status can be a reliable alternative for predicting clinical behavior of POS at small biopsies.

Parosteal osteosarcoma: a monocentric retrospective analysis of 195 patients.

Parosteal osteosarcoma is a low-grade malignant bone tumor that can undergo dedifferentiation. The aim of this study was to analyze clinicopathologic features associated with clinical outcome in a large cohort of patients. Patients consecutively treated for parosteal osteosarcoma at Rizzoli Orthopedic Institute from 1900 to 2018 were reviewed and analyzed. Clincopathologic data of 195 patients with parosteal osteosarcoma were analyzed. Age at diagnosis ranged from 9 to 75 years (median 31). Median follow-up time was 150 months (range, 3-720). The most common tumor locations were femur (61.5%), humerus (15.9%) and tibia (12.8%). Wide surgical margins were achieved in 125 (64.1%) patients. Medullary involvement was present in 69 (35.4%) cases. Dedifferentiation occurred in 48 (24.6%) patients. Forty-five patients developed recurrence (23.1%; median time to recurrence of 36 months). At last follow-up, 155 (79.5%) patients were alive and without evidence of disease, 8 (4.1%) were alive with active disease, 23 (11.8%) died from disease, and 9 (4.6%) from unrelated causes. Patients with dedifferentiated parosteal osteosarcoma had worse 5-year (65% versus 96%) and 10-year survival (60% versus 96%) when compared to conventional tumors (P < .001). Wide surgical margins had positive impact on both disease-free (P < .001) and overall survival (P = .036). Medullary involvement, age at presentation and tumor size had no impact on survival. Dedifferentiation is the most important factor that negatively impacts clinical outcome. Surgical aim is to ensure radical removal with wide surgical margins to improve disease-free survival.

A rare rib lesion due to parosteal osteosarcoma: a case report.

INTRODUCTION: Masses which develop on the surface of the rib bones are rare. The differential diagnosis includes benign and malignant lesions. CASE PRESENTATION: A 23-year-old European woman presented at an out-patient clinic with a 9-month history of a painless swelling on the right posterolateral side of her chest wall. The case reported here is of a very rarely seen parosteal osteosarcoma of the rib that was treated with wide resection and chest wall reconstruction. There was no evidence of local recurrence or distal metastasis after a 1-year follow-up. CONCLUSION: Parosteal osteosarcoma is a locally aggressive malignant tumor, and resection with a wide margin is the most appropriate treatment. Correct diagnosis of parosteal osteosarcoma is challenging for an orthopedic surgeon. Although rare, in the differential diagnosis of lesions located on the ribs, parosteal osteosarcoma should be considered and a systematic diagnostic approach should be taken.

[Dedifferentiated diaphyseal juxtacortical osteosarcoma of ulna with metastasis to the lung]. / Osteosarcoma parostal desdiferenciado en diáfisis de cúbito metastásico a pulmón.

Dedifferentiated parosteal osteosarcoma is a variant in which a high grade osteosarcoma coexists with a parosteal osteosarcoma. We report the case of a 20-year-old female patient who presented with six months of evolution of pain and functional limitation of the right forearm, with no apparent cause; radiographs were performed, observing a tumoral lesion in the diaphysis of the right ulna. Physical examination showed pain upon palpation in the diaphysis of the ulna and limitation of prone-supination. Axial computed tomography of the thorax revealed metastatic disease in the upper lobe of the left lung. An incisional biopsy was performed on the right ulna, with a report of dedifferentiated parosteal osteosarcoma. Therefore, the patient was managed with neoadjuvant chemotherapy with cisplatin and doxorubicin until completing three cycles. Surgical treatment consisted of intercalary resection of the diaphysis of the right ulna, plus reconstruction of the microvascularized autologous graft of the right fibular diaphysis and graft stabilization with 3.5 mm dynamic compression plate (DCP) and one-third tubular plate. In the same procedure, pulmonary metastasectomy was performed by thoracoscopy. Post-surgical histopathological report with 100% necrosis. Currently, the patient is asymptomatic, with no evidence of tumor activity. Dedifferentiated parosteal osteosarcoma is a rare pathology, but should be suspected as a differential diagnosis in the presence of a parosteal osteosarcoma; it should be taken into account that this disease can metastasize due to its dedifferentiated pattern. It is important to plan a surgical treatment that allows an adequate functional reconstruction, always taking into account the oncological principle.

El osteosarcoma parostal desdiferenciado es una variante en la cual un osteosarcoma de alto grado coexiste con un osteosarcoma parostal. Se presenta el caso de un paciente femenino de 20 años; acudió con seis meses de evolución de dolor y limitación funcional en el antebrazo derecho sin causa aparente; se le realizaron radiografías, donde se observó una lesión tumoral en la diáfisis del cúbito derecho. A la exploración física, presentó dolor a la palpación en la diáfisis del cúbito y limitación a la pronosupinación. La tomografía axial computada de tórax reveló enfermedad metastásica en el lóbulo superior del pulmón izquierdo. Se le efectuó una biopsia incisional de la tumoración en el cúbito derecho, con reporte de osteosarcoma parostal desdiferenciado. Por ello, inició manejo con quimioterapia neoadyuvante con cisplatino y doxorrubicina hasta completar tres ciclos. El tratamiento quirúrgico consistió en resección intercalar de la diáfisis del cúbito derecho más reconstrucción de injerto autólogo microvascularizado de la diáfisis del peroné derecho y estabilización del injerto con placa de compresión dinámica (DCP) 3.5 mm y placa tercio de caña. En el mismo procedimiento se le efectuó metastasectomía pulmonar por toracoscopía. El reporte histopatológico postquirúrgico, con necrosis de 100%. Actualmente, la paciente se encuentra asintomática, sin datos de actividad tumoral. El osteosarcoma parostal desdiferenciado es una patología rara, pero que se debe sospechar como diagnóstico diferencial ante un osteosarcoma parostal; se debe tener en cuenta que esta enfermedad puede generar metástasis por su patrón desdiferenciado. Es importante planificar un tratamiento quirúrgico que permita una adecuada reconstrucción funcional, siempre teniendo en cuenta el principio oncológico.

Can imaging distinguish between low-grade and dedifferentiated parosteal osteosarcoma?

BACKGROUND: Most instances of the parosteal osteosarcoma (OGS) are low-grade tumors. However, some parosteal OGSs undergo dedifferentiated transformation. Dedifferentiated parosteal OGS can cause distant metastasis and poor survival, and preoperative chemotherapy may be warranted. This study provides imaging clues for dedifferentiated parosteal OGS before treatment. METHODS: The study retrospectively enrolled 23 patients with histologically proven parosteal OGS, including 69.6% (n = 16) low-grade and 30.4% (n = 7) dedifferentiated types. Preoperative images including radiography and magnetic resonance imaging were reviewed. The following imaging parameters and clinical outcomes were evaluated: 1) average age; 2) sex; 3) tumor size; 4) presence of string sign; 5) necrosis; 6) hemorrhage; 7) solid soft tissue component; 8) perforating vessels; 9) ossification grade; 10) marginal ossification; 11) periosteal reaction; 12) sunburst reaction; 13) bone marrow edema; 14) bone marrow invasion; 15) perifocal soft tissue edema; 16) adjacent joint involvement; 17) adjacent neurovascular bundle compression; 18) regional lymph node; 19) bone metastasis; 20) preoperative lung metastasis; 21) follow-up lung metastasis; and 22) recurrence. RESULTS: The average maximal tumor sizes were 7.1 cm and 10.9 cm in low-grade and dedifferentiated types, respectively (p = 0.033). Sunburst periosteal reaction was visualized in two cases of low-grade type (12.5%) and four cases of the dedifferentiated type (57.1%) (p = 0.025) of parosteal OGS. None of our studied cases revealed preoperative lung metastasis. In the follow-up chest computed tomography, lung metastasis was noted in two cases of conventional type (14.2%), and four cases of dedifferentiated type (57.1%) (p = 0.040) of parosteal OGS. In receiver operating characteristic (ROC) curve analysis, the average tumor size and sunburst periosteal reaction showed good specificity (AUC = 0.070 and 0.072, respectively). CONCLUSION: Compared with low-grade types, dedifferentiated parosteal OGS exhibits a considerably larger tumor size, more sunburst periosteal reaction, and a more frequent development of lung metastasis in the disease course. Tumor size and sunburst periosteal reaction are the most crucial imaging diagnostic factors.

Osteosarcoma parostal desdiferenciado en diáfisis de cúbito metastásico a pulmón / Dedifferentiated diaphyseal juxtacortical osteosarcoma of ulna with metastasis to the lung

Resumen: El osteosarcoma parostal desdiferenciado es una variante en la cual un osteosarcoma de alto grado coexiste con un osteosarcoma parostal. Se presenta el caso de un paciente femenino de 20 años; acudió con seis meses de evolución de dolor y limitación funcional en el antebrazo derecho sin causa aparente; se le realizaron radiografías, donde se observó una lesión tumoral en la diáfisis del cúbito derecho. A la exploración física, presentó dolor a la palpación en la diáfisis del cúbito y limitación a la pronosupinación. La tomografía axial computada de tórax reveló enfermedad metastásica en el lóbulo superior del pulmón izquierdo. Se le efectuó una biopsia incisional de la tumoración en el cúbito derecho, con reporte de osteosarcoma parostal desdiferenciado. Por ello, inició manejo con quimioterapia neoadyuvante con cisplatino y doxorrubicina hasta completar tres ciclos. El tratamiento quirúrgico consistió en resección intercalar de la diáfisis del cúbito derecho más reconstrucción de injerto autólogo microvascularizado de la diáfisis del peroné derecho y estabilización del injerto con placa de compresión dinámica (DCP) 3.5 mm y placa tercio de caña. En el mismo procedimiento se le efectuó metastasectomía pulmonar por toracoscopía. El reporte histopatológico postquirúrgico, con necrosis de 100%. Actualmente, la paciente se encuentra asintomática, sin datos de actividad tumoral. El osteosarcoma parostal desdiferenciado es una patología rara, pero que se debe sospechar como diagnóstico diferencial ante un osteosarcoma parostal; se debe tener en cuenta que esta enfermedad puede generar metástasis por su patrón desdiferenciado. Es importante planificar un tratamiento quirúrgico que permita una adecuada reconstrucción funcional, siempre teniendo en cuenta el principio oncológico.

Abstract: Dedifferentiated parosteal osteosarcoma is a variant in which a high grade osteosarcoma coexists with a parosteal osteosarcoma. We report the case of a 20-year-old female patient who presented with six months of evolution of pain and functional limitation of the right forearm, with no apparent cause; radiographs were performed, observing a tumoral lesion in the diaphysis of the right ulna. Physical examination showed pain upon palpation in the diaphysis of the ulna and limitation of prone-supination. Axial computed tomography of the thorax revealed metastatic disease in the upper lobe of the left lung. An incisional biopsy was performed on the right ulna, with a report of dedifferentiated parosteal osteosarcoma. Therefore, the patient was managed with neoadjuvant chemotherapy with cisplatin and doxorubicin until completing three cycles. Surgical treatment consisted of intercalary resection of the diaphysis of the right ulna, plus reconstruction of the microvascularized autologous graft of the right fibular diaphysis and graft stabilization with 3.5 mm dynamic compression plate (DCP) and one-third tubular plate. In the same procedure, pulmonary metastasectomy was performed by thoracoscopy. Post-surgical histopathological report with 100% necrosis. Currently, the patient is asymptomatic, with no evidence of tumor activity. Dedifferentiated parosteal osteosarcoma is a rare pathology, but should be suspected as a differential diagnosis in the presence of a parosteal osteosarcoma; it should be taken into account that this disease can metastasize due to its dedifferentiated pattern. It is important to plan a surgical treatment that allows an adequate functional reconstruction, always taking into account the oncological principle.

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

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

Parosteal osteosarcoma of mandible: A rare case report.

With the exception of multiple myelomas, osteosarcoma is the most frequently occurring primary malignant bone tumor with an overall incidence of 1:100,000/year. It has greatest predilection for the metaphyses, most frequently femur and tibia. However, osteosarcomas affecting the craniofacial bones are infrequent. Two main types: intramedullary and juxtacortical varieties are seen. Juxtacortical variety is further subdivided into periosteal and parosteal variants. Due to its rarity, only 13 cases of parosteal osteosarcoma have been reported till date. A 35-year-old male patient with affected postirradiated mandible is being reported as the 14th case of this kind with its unique benign presentation and less aggressive nature.