What are the Oncologic and Functional Outcomes After Joint Salvage Resections for Juxtaarticular Osteosarcoma About the Knee?

BACKGROUND: Joint salvage surgery for patients with juxtaarticular osteosarcoma remains challenging, especially when the tumor invades the epiphysis. Because patients are surviving longer with current chemotherapy regimens, it is advantageous to retain native joints if possible, especially in young patients. However, the results using joint-preserving tumor resections in this context have not been well characterized. QUESTIONS/PURPOSES: (1) What are the functional outcomes after limb salvage surgery at a minimum of 3 years? (2) What are the oncologic outcomes? (3) Is joint salvage surgery for epiphyseal tumors associated with an increased risk of local recurrence compared with metaphyseal tumors not invading the epiphysis? (4) What are the complications associated with joint salvage surgery? METHODS: Between 2004 and 2013, we treated 117 patients with juxtaarticular osteosarcoma; of those, 43 (38%) were treated with joint salvage surgery, and 41 (95%) of the 43 patients are included in our study. The other two (5%) were lost to followup before 3 years (mean, 4.4 years; range, 3-11 years,). During the period in question, we generally performed joint salvage surgery in these patients when they had a favorable response to chemotherapy, did not have a pathologic fracture or extrusion of the tumor into the joint, and did not have a whole-epiphyseal osteolytic lesion, a large mass, or obvious neurovascular involvement. This report is a followup of an earlier study; the current study includes an additional nine patients, and additional followup of a mean of 19 months for the patients included in the earlier report. We ascertained overall survival and survival free from local recurrence which was estimated using the Kaplan-Meier method, functional status of the limb which was evaluated using the Musculoskeletal Tumor Society (MSTS)-93 scoring system, and recorded reconstructive complications including infection, fracture, skin necrosis, and nonunion. We compared oncologic and functional outcomes between patients with (n = 28) and without tumor extension to epiphysis (n =13). We also compared oncologic and functional outcomes among patients with different adjuvant treatments including microwave ablation (n = 11), cryoablation (n = 12), and navigation-assisted osteotomy (n = 5). Complications were tallied using records from our institutional database. RESULTS: The overall Kaplan-Mayer survival rate was 82% (95% CI, 104-128 months) at 5 years. The overall Kaplan-Meier survivorship from local recurrence was 91% at 5 years (95% CI, 115-133 months). Three patients had a local recurrence, but none had local recurrence in or close to the remaining epiphysis. The MSTS scores ranged from 22 to 30 points, with a median of 28. There were no differences in survival rate, local recurrence, or MSTS scores between patients with a tumor that did not invade the epiphysis and those in whom the tumor did invade the epiphysis. There were differences in MSTS scores among patients with epiphyseal tumor extension in which different adjuvant techniques, including microwave ablation, cryoablation, and navigation-assisted osteotomy, were used. Additional surgical procedures were recorded for 10 patients (24%). Osteonecrosis of the residual epiphysis was detected 13 patients (31%). CONCLUSIONS: Our findings suggest it is possible to salvage joints in selected patients with juxtaarticular osteosarcoma around the knee. The patients who have a favorable response to chemotherapy are the best candidates for this approach. Future studies might explore the role of adjuvant techniques of microwave ablation and cryoablation, particularly when the tumor invades the epiphysis, and whether resections can be facilitated with navigation. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Precise resection and biological reconstruction under navigation guidance for young patients with juxta-articular bone sarcoma in lower extremity: preliminary report.

BACKGROUND: It is a challenge to perform a joint-preserving resection for young patients with juxta-articular bone sarcomas. We determined whether osteotomy under image-guided navigation make joint-saving resection possible for juxta-articular lesions while adhering oncological principles. METHODS: Between June 2008 and July 2010, joint-preserving limb salvage surgeries were performed on 9 patients with juxta-articular bone sarcomas under navigation guidance. Computed tomography/magnetic resonance imaging fusion images were used for real-time navigation. Eight lesions located around the knee and 1 in hip. Six tumors extend to and 3 beyond the epiphyseal line. Planned osteotomy under image-guided navigation was employed for achieving clear surgical margin while maximizing host tissue preservation. All tumors were en bloc removed and intercalary defect were reconstructed by combination of allograft with vascularized fibula graft. All specimens were examined for resection margin. Patients were followed up for an average of 25.2 months for evaluating of functional and oncology outcomes. RESULTS: Entire joint were preserved in 6 patients and part of joint were saved in another 3 patients. The mean registration error for navigation was 0.40 mm (range, 0.31 to 0.62 mm). Clear surgical margin was obtained in all specimens. The average closest distance between the osteotomy line and tumor edge was 9.6 mm (range, 6 to 14 mm). Entire joint cartilage was preserved in 6 patients and portion of joint were saved in 3 patients (2 in proximal tibia, 1 in distal femur). No patient experienced local recurrence. Two patients developed lung metastasis. One died of disease and the other underwent metastasectomy and had no evidence of disease at the most recent follow-up. All reconstruction was in situ with the Musculoskeletal Tumor Society average score of 26.7 at final follow-up. CONCLUSIONS: With careful patient selection, image navigation-assisted surgery made it possible to resect the bone exactly as planned in length and orientation in the magnetic resonance imaging image, yielding a clear margin and preserving the entire or part of the articular cartilage in joint-sparing limb salvage procedures for treating skeletally immature patients with juxta-articular bone sarcomas. LEVEL OF EVIDENCE: Level IV--therapeutic study.

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.

[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.

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.

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.

Local recurrence of a parosteal osteosarcoma 21 years after incomplete resection.

Parosteal osteosarcoma (POS) is the most common form of surface osteosarcoma. Its symptoms are insidious and its duration prior to diagnosis is considerably longer than that of other types of osteosarcoma. We report a case of POS with a growing mass but no evidence of metastasis. This tumor, which was diagnosed as calcified hematoma with benign characteristics, was incompletely resected in our hospital 21 years before the diagnosis of recurrence. The patient underwent a wide en bloc resection in our hospital and was free of symptoms, with no signs of tumor recurrence or metastasis during a 53-month follow-up.

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.

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.

Recurrence of juxtacortical chondrosarcoma arising on the rib.

Juxtacortical chondrosarcoma developing on the surface of a bone is quite rare. We report a case of juxtacortical chondrosarcoma arising on the fourth rib of a 76-year-old man. Intraregional tumor resection was performed, but local recurrence was detected after 6 months. The patient underwent wide resection including the ribs, and reconstruction of the thoracic wall. He was released with a good prognosis after a year. This case emphasizes the importance of biopsy analysis before surgery to carefully evaluate tumor spread in the cartilage and performing wide resection even if the tumor is easily separated from the bone.

Parosteal osteosarcoma from a rib.

Comprising 1.6% of primary bone malignancies, parosteal osteosarcomas are rare. Rib parosteal osteosarcomas are even rarer, with only 2 cases in the literature. We report a third such case, with a 32-month disease-free survival. Issues relevant to the management of rib parosteal osteosarcomas are discussed.

Parosteal osteosarcoma of the posterior aspect of the distal part of the femur. Oncological and functional results following a new resection technique.

BACKGROUND: Parosteal osteosarcoma is a low-grade malignant bone tumor that arises from the surface of the metaphysis of long bones. Parosteal osteosarcoma is usually well differentiated and displays a low propensity to metastasize. Wide resection of a parosteal osteosarcoma has been shown to provide a relatively risk-free method of preventing local recurrence. We propose a new method of resection of parosteal osteosarcomas located in the popliteal paraosseous space of the distal part of the femur. This method involves resection of the mass through separate medial and lateral incisions, which allows for wide margins yet limits the amount of dissection of the soft tissues and the neurovascular bundle. METHODS: Six patients with parosteal osteosarcoma located on the posterior aspect of the distal part of the femur underwent resection of the lesion and reconstruction with a posterior hemicortical allograft through dual medial and lateral incisions. The patients were evaluated with regard to pain, postoperative function, union of the allograft (osteosynthesis), and the prevalence of local recurrence. RESULTS: The average time until the last follow-up assessment was 4.3 years. No metastases developed, and there were no local recurrences. All patients were free of disease at the last follow-up evaluation. Postoperatively, the average range of motion of the knee was 0 to 122 degrees. Five of the six patients were free of pain at the time of the latest follow-up. Five of the six patients returned to their preoperative active functional status. CONCLUSIONS: We recommend resection of a parosteal osteosarcoma located on the posterior surface of the femur through separate medial and lateral incisions. This approach provides minimal dissection of the neurovascular bundle but ample exposure for reconstruction with a hemicortical allograft.

Parosteal osteosarcoma. A clinicopathological study.

The records of 226 patients (sixty-seven who were managed at our institution and 159 who were identified from the consultation files) who had had a parosteal osteosarcoma were reviewed. The criteria for diagnosis were that, roentgenographically, the lesion had arisen from the surface of the bone and that, histologically, the tumor was well differentiated (Grade 1 or 2); it was characterized by well formed osteoid within a spindle-cell stroma; and, when there was medullary involvement, less than 25 per cent of the medullary cavity was affected. Dedifferentiation was more common (16 per cent of the patients) than previously reported and was associated with a poor prognosis. Cross-sectional imaging studies demonstrated medullary involvement in 22 per cent of the patients, an unmineralized soft-tissue mass peripheral to the mineral component in 51 per cent, and adjacent soft-tissue invasion in 46 per cent. In contrast to the findings in our previous studies, medullary involvement was not a poor prognostic factor. At an average of thirteen years (range, two to forty-one years), eleven of the sixty-seven patients who were managed at our institution died of the tumor; ten of these patients had a dedifferentiated tumor. Statistical analysis of the thirty-nine patients who had had the primary treatment at our institution revealed that incomplete resection was associated with an increased risk of local recurrence and that dedifferentiation markedly increased the risk of metastasis.

Stanmore custom-made extendible distal femoral replacements. Clinical experience in children with primary malignant bone tumours.

The use of extendible distal femoral replacements is a relatively new treatment alternative for malignant bone tumours in growing individuals. Although their appearance was widely appreciated, questions about functional practicality and longevity remain unclear. With longer follow-up, advantages of immediate functional restoration and beneficial psychological aspects seem to be overshadowed by an increase in complications such as aseptic loosening, infection or prosthetic failure. We have reviewed 18 children with such tumours who were treated between 1983 and 1990 by custom-made Stanmore extendible distal femoral replacements. Four died from metastatic disease within 2.5 years of operation and two required amputation for local recurrence or chronic infection. The remaining 12 patients were followed for a mean of 8.7 years (6 to 13.2). A mean total lengthening of 5.2 cm was achieved, requiring, on average, 4.3 operations. Using the Musculoskeletal Tumor Society rating score the functional result at review was, on average, 77% of the expected normal function, with seven patients achieving > or = 80%. Revision of the prosthesis was required in ten patients, in six for aseptic loosening, at a mean of 6.2 years after the initial procedure.

Parosteal osteosarcoma of the ring finger metacarpal in a semi-professional pianist.

We report treatment of a low grade parosteal osteosarcoma of the ring finger metacarpal in a patient who would not contemplate ray amputation because of her career. Surgery involved excision of the bone, extracorporeal radiation then re-implantation.

Parosteal osteosarcoma of the skull.

Parosteal osteosarcoma of the skull is a distinct surface bone tumor, with a better prognosis than conventional osteosarcoma. The most common location is on the surface of the distal femur which accounts for 46-66% of the cases. The presentation in the skull is uncommon and there are few cases reported in the literature. We describe the case of a man who developed a parosteal osteosarcoma arising from the occipital bone with extension to the parietal bone. The patient was operated and had a complete tumor resection.

[Parosteal osteosarcoma: a clinical study of 48 cases].

OBJECTIVE: To investigate the way of diagnosis and therapy of parosteal osteosarcoma. METHODS: A retrospective review was conducted of 48 patients treated at our department between June 1964 and December 2001. The average age of patients in this study was 29.2 years (13 - 47 years). Thirty-two of the patients were female; sixteen were male. The single most common site is the posterior aspect of the distal femur (in 36 patients), followed by the femur shaft (in 6 patients), the proximal tibia (in 2 patients), etc. Nine patients had been operated on before referral to our department. RESULTS: The average follow-up period from the first operation was 5.2 (0.25 - 24) years. In 36 of the 39 patients in whom a limb-salvage procedure was performed, a segment of the tumor-bearing bone was excised along with the tumor, whereas in 3 patients only the subadjacent cortex was excised with the tumor. In the limb-sparing group, the reconstruction was achieved by means of attenuated tumor bone or allograft in 23 cases, by endoprosthetic replacement in 9 cases, and by allograft replacement in 4 cases. The local resections were wide in 35 cases, and marginal in 13 cases. After marginal surgery, local recurrence occurred in 5/13 patients, whereas it occurred in 3/35 patients treated with wide resection. Pulmonary metastases developed in 6 patients, four patients died, and 2 patients are alive with disease. There were 4 cases of fractures of bone grafts. Four patients developed an infection. Long-term survival rate is 85.8%. For tumors that invaded the medullary canal there was no statistical association with local recurrence or metastasis. There is statistical significance between surgical margin and local recurrence. CONCLUSIONS: Wide surgical excision alone is adequate treatment for patients with conventional parosteal osteosarcoma. A tumor-free margin remains the critical factor determining overall prognosis. When a marginal excision was knowingly done to preserve a major neurovascular bundle, the risk of recurrence was less than when it was done to shell-out a presumptively benign lesion. Repeated recurrence probably increases the risk of dedifferentiation and thereby worsens the prognosis. Recurrent lesions with multiple soft-tissue satellite nodules or involvement of the neurovascular structures may however require amputation to provide sufficient local control when a wide margin cannot be achieved. An individualized resection will be performed in the future probably under the help of the advanced technique of image to distinguish the reactive zone from the normal tissue precisely.

Parosteal osteosarcoma.

A case of parosteal osteosarcoma is reported. In spite of the pathognomonic plain radiographic signs of parosteal osteosarcoma, it is very uneasy to differentiate it from myositis ossificans circumscripta in the mature stage. CT and MRI defined the extent of the tumor into the soft tissue, the medullary and cortical invasion and gave more information about the composition of the lesion.

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.