Low-grade parosteal osteosaracoma of the ulna with dedifferentiation into high-grade osteosarcoma

 This report describes a low-grade parosteal osteosarcoma of the ulna with dedifferentiation into high-grade osteosarcoma. The clinical, pathological, and imaging findings are described and discussed.     

Telangiectatic dedifferentiation of a parosteal osteosarcoma

A unique case of parosteal osteosarcoma (POS) of the proximal femur, with areas of telangiectatic dedifferentiation, in a 28-year-old woman is reported. The patient had a 7-week history of pain and swelling in her right thigh. A biopsy diagnosis of POS was established. The patient was treated with two cycles of intra-arterial chemotherapy, followed by limb salvage surgery. Histological examination of the resected specimen showed POS with areas of dedifferentiation composed of high-grade telangiectatic osteosarcoma with associated secondary aneurysmal bone cyst change. Received: 17 April 1998 Revision requested: 11 May 1998 Revision received: 9 May 2000 Accepted: 11 May 2000     

Parosteal osteosarcoma of a metatarsal with intramedullary invasion

A 70-year-old man presented with increasing swelling of 2 years’ duration, on the dorsal aspect of the forefoot. Imaging studies revealed a heavily calcified surface lesion of bone with early invasion of the underlying second metatarsal. Both imaging findings and the subsequent resection histology were consistent with a parosteal osteosarcoma, which is particularly rare at this site and at this age. The differential diagnosis of a mineralizing surface lesion of bone arising in the foot is discussed. Received: 2 June 1998 Revision requested: 8 August 1998 Revision received: 16 November 1998 Accepted: 17 November 1998     

Multifocal osteosarcoma as second tumor after childhood retinoblastoma

We present a case of multifocal osteosarcoma (MFOS) arising 11.5 years after successful treatment of bilateral retinoblastoma. The clinical, imaging and pathological findings at onset, after therapy, and during follow-up are described. Fluorescent in situ hybridization did not reveal a deletion of the RB-1 retinoblastoma gene, although the presence of an inactivating mutation invisible to this method cannot be ruled out. The MFOS may have been a second multifocal tumor associated with the original retinoblastoma or a post-irradiation sarcoma with extensive metastases. Received: 20 November 1998 Revision requested: 5 January 1999 Revision received: 8 March 1999 Accepted: 19 March 1999     

Epiphyseal osteoblastoma-like osteosarcoma

Osteoblastoma-like osteosarcoma is a rare variant of osteosarcoma occurring in this instance in a highly unusual location: the lateral femoral condyle of a 13-year-old girl. The radiological features were non-aggressive and, although slightly unusual, were most suggestive of chondroblastoma.Presented at the Closed Meeting of the International Skeletal Society, Geneva, Switzerland, September 2003     

Extraskeletal osteosarcoma arising in myositis ossificans

A 53-year-old woman had extraskeletal osteosarcoma that developed from a soft tissue bony mass present on the volar aspect of the left wrist for 4 years. Initially, the bony mass was soft and movable, but during the first year it became hard and fixed. The patient had no history of trauma. Because the lesion did not grow or cause any symptoms, the patient did not come to the hospital until 4 years after she first noticed the lesion. Radiologically, the bony mass had features characteristic of mature myositis ossificans, showing ”eggshell” ossification. A nonmineralized soft tissue mass occurred between the surface of the radius and the bony shell. Histologically, a high-grade osteosarcoma was present between the surface of the radius and the well-differentiated bone tissue, which included fatty and hematopoietic marrow. All the findings indicated that our patient had an extremely rare case of malignant transformation of myositis ossificans. Received: 22 June 2000 Revision requested: 2 August 2000 Revision received: 14 September 2000 Accepted: 25 September 2000     

Dedifferentiated parosteal osteosarcoma with rhabdomyosarcomatous differentiation

Dedifferentiated parosteal osteosarcomas are characterized histologically by the combination of low-grade fibroblastic osteosarcoma admixed with a high-grade component that typically has the appearance of malignant fibrous histiocytoma or osteosarcoma. Herein we report a case of dedifferentiated parosteal osteosarcoma of the distal femur, in which the high-grade component consisted of rhabdomyosarcoma. To our knowledge, a rhabdomyosarcomatous component has not been described previously in a dedifferentiated parosteal osteosarcoma. The clinical, radiologic, and pathologic features of this rare type of surface osteosarcoma are described. Received: 1 March 1999 Revision requested: 6 April 1999 Revision received: 27 Apri1 1999 Accepted: 29 April 1999     

Ossifying fibromyxoid tumor resembling parosteal osteosarcoma

Ossifying fibromyxoid tumor (OFMT) is a rare soft tissue neoplasm which varies in the amount of bone tissue laid down. We report on a case of OFMT in a 59-year-old male which mimicked a large parosteal osteosarcoma on radiography, MRI, and CT. T1-weighted MR images showed high-intensity areas which reflected fatty marrow. The metaplastic bone was connected to the cortex of the femur, but the tumor did not involve the medullary cavity. The tumor was irradiated and the patient was administered chemotherapy. Wide excision of the tumor and hip rotation plasty was performed. The patient has been disease free for 18 months.     

Microscopic intraosseous extension of osteosarcoma: assessment on dynamic contrast-enhanced MRI

 Objective. This study investigated whether dynamic MRI could determine microscopic intraosseous invasion in osteosarcoma. Patients. Six patients with osteosarcoma who underwent total resection of the tumor after chemotherapy were studied. Design. The steepest slope value of the time-intensity curve was calculated on the basis of the first-pass method on dynamic MRI performed after chemotherapy. Slope value modified log=[100·(SI_b−SI_a)/(T_b−T_a)/SI_a], where SI_a and SI_b represent the signal intensity at time points T_a and T_b when the steepest slope started and ended, respectively. The slope value was correlated with the histological findings of the surgical specimens. The findings on conventional MRI were also reviewed. Results and conclusions. In five of six patients microscopic tumor invasion ranging from 1 to 3.5 cm in depth was pathologically proven. The slope value within the microscopic invasion (−0.052±0.267) was significantly greater than that of tumour-free marrow (−0.609±0.220) and less than that in areas showing macroscopic tumor invasion (0.595±0.483) (P<0.001). Histological examination disclosed the dilatation of small vessels within the macroscopic and microscopic invasion. Findings on conventional MRI varied among patients; microscopic invasion was not detected in one, underestimated in two, and overestimated in two. It is concluded that calculation of the slope value on dynamic MRI can discriminate regions of microscopic invasion from tumor-free marrow in patients with osteosarcoma after chemotherapy.     

Intracortical osteosarcoma

Intracortical osteosarcomas originate in the bone cortex and represent the rarest type of osteosarcoma. We describe the clinical, radiological and histological features of an intracortical osteosarcoma occurring in the femur of a young man and discuss the pertinent features of this tumour compared to those previously reported.     

Soft tissue osteosarcoma with telangiectatic features: MR imaging findings in two cases

Extraskeletal osteosarcomas are rare tumors, and the telangiectatic variety is the least common histological variety in this group. This report describes the clinical and MR imaging findings in two cases arising in the pretibial soft tissues. Both tumors demonstrated marked inhomogeneity with T2-weighted spin echo and STIR sequences. One of the tumors revealed numerous fluid levels within the lesion. A review of the MRI features of these tumors is provided. Osteosarcoma with telangiectatic features should be considered in the differential diagnosis of a soft tissue mass with fluid-fluid levels in patients 40 years of age or older.     

Synchronous multicentric osteosarcoma: the case for metastases

 Objective. There is a current debate whether multicentric osteosarcoma represents synchronous multiple primary osteosarcomas or metastatic disease. The purpose of this report is to evaluate the etiology, presentation, and classification of this entity. Design and patients. Six patients ranging in age from 7 to 29 years were studied. The clinical, radiographic, and pathologic findings are reported. In addition, a review of the literature was undertaken. Results. The clinical courses of our six patients as well as a review of the literature suggest that multicentric osteosarcoma represent one extreme of a continuous scale of metastatic osteosarcoma rather than multiple synchronous primary tumors. The presentation is unusual and the clinical behavior distinctive, but the mechanism of spread remains the same: blood-borne and lymphatic-borne. Conclusions. Our experience with these six patients supports the concept in the recent literature that synchronous osteosarcoma is one extreme of the spectrum of metastatic osteosarcoma. Its unique features are: (1) multiple radiodense lesions that present simultaneously with or without pulmonary metastases; (2) a single ”dominant” lesion with multiple smaller lesions; and (3) a uniformly rapid, fatal prognosis. Osteosarcoma should be regarded as a metastatic disease, even when only a single primary lesion is found at the initial presentation.     

Chondroblastic osteosarcoma: characterisation by gadolinium-enhanced MR imaging correlated with histopathology

Objective. To identify specific features of chondroblastic osteosarcoma on gadopentetate dimeglumine (Gd)-enhanced magnetic resonance (MR) imaging. Design and patients. Nine patients with chondroblastic osteosarcoma and a control group of 20 patients with conventional central osteosarcoma were included in this study. The histopathological findings of the surgical specimens were compared with enhancement patterns on static Gd-enhanced MR images. Results. In chondroblastic osteosarcoma septonodular and peripheral rim enhancement represented tumour with a pure chondroid matrix. Non-enhancing and heterogeneous enhancing areas represented tumour with both chondroid and osteoid matrix. In the tumours in the control group enhancement was predominantly heterogeneous but in one it was homogeneous. All these areas corresponded to necrotic or viable osteoid tumour tissue or fibrovascular tissue in areas of necrosis. Conclusion. Gd-enhanced MR imaging can assist in obtaining diagnostic biopsy material of chondroblastic osteosarcoma by identifying both osteoid- and chondroid-forming areas.     

Primary osteosarcoma of a metatarsal bone

Although osteosarcoma is the most common primary bone malignancy of childhood and adolescence that is not related to marrow cells, involvement of the short tubular bones is uncommon. In contrast to more conventional sites, where the tumor is usually high grade and found in adolescents, osteosarcoma of the small bones is more likely to be low grade, and is often seen in older individuals. We present a case of low-grade primary osteosarcoma of a metatarsal bone in a 25-year-old woman. Received: 22 December 1998 Revision requested: 3 February 1999 Revision received: 24 April 2000 Accepted: 26 April 2000     

Dedifferentiated high-grade osteosarcoma originating from low-grade central osteosarcoma of the fibula

Low grade central osteosarcoma is a distinct, rare low grade malignant neoplasm characterized histologically by a spindle cell proliferation associated with trabecular bone formation. This tumor usually carries a good prognosis. However, it has the potential to recur, dedifferentiate, and metastasize subsequent to surgical treatment. In extremely rare occasions, LGCOS presents with areas of dedifferentiation upon initial patient evaluation. In this report we describe one such case affecting the fibula of a 39-year-old female, presenting with pain. Initial biopsy demonstrated a high-grade osteosarcoma. No areas of LGCOS were seen histologically. Following biopsy the patient received 3 months of chemotherapy at a different institution. However, the patient continued to exhibit symptoms. X-rays indicated a very aggressive tumor in the diaphysis of the proximal fibula, MRI revealed soft tissue involvement. The tumor and surrounding soft-tissues were excised en bloc at our institution. Microscopically, the lesion consisted of high-grade osteosarcoma as well as an underlying LGCOS that involved the cortex and medullary cavity of the fibula. The two histological components of the tumor were sharply delineated from one another. No chemotherapy effect was appreciated histologically or clinically. Eight months following the surgery, the patient died from lung metastases. This is the third documented case of dedifferentiated LGCOS at initial presentation. This case reveals that the low-grade component was also evident on preoperative radiographs.     

Post-radiation osteosarcoma of the scapula

 Osteosarcomas arising in irradiated tissues are uncommon but important complications of radiotherapy. Radiation-induced osteosarcomas generally occur 3–30 years after exposure and are most common after radiotherapy for cervical or breast carcinoma. These tumors are usually rapidly growing, extremely painful, and histologically high grade. In this paper, we report two cases of high-grade post-radiation osteosarcoma of the scapula. Despite being almost identical radiologically and pathologically, one case had a typical clinical presentation whereas the second case had two unusual features, being non-painful and arising in a field initially irradiated for bronchogenic carcinoma.     

Post-Paget telangiectatic osteosarcoma of the skull

Sarcomatous transformation is the most dreaded complication of Paget’s disease. We report on a case of post-Paget telangiectatic osteosarcoma of the skull, a variant of osteogenic osteosarcoma, in a 79-year-old woman. We discuss the radiological pattern in relationship to the differential diagnosis. Received: 27 July 1998 Revision requested: 24 August 1998, 23 December 1998 Revision received: 25 November 1998, 12 April 1999 Accepted: 13 April 1999     

Small-cell osteosarcoma

Small-cell osteosarcoma, a subtype of osteogenic sarcoma, consists of sheets of round cells that produce an osteoid matrix. It may be confused with Ewing sarcoma if the osteoid matrix is not included in the biopsy. The distinctive radiographic features of an osteoblastic tumor and a pattern of permeative destruction will confirm the histologic diagnosis or indicate the true nature if tumor osteoid is not included in the histological sections. We add 13 patients to the 32 previously reported in the literature. Fourteen (31%) of the 45 are living and well, though three have been followed for only 2 months (Tables 1 and 2). The treatments have been so varied that a statistically significant evaluation cannot be developed. The radiographic features are not distinctive, but the diagnosis may be suggested when a tumor has osteoblastic features in the metaphysis and extends well down into the shaft with a pattern of permeative destruction. The radiographic features are especially important when limited biopsies reveal only sheets of round cells, thus suggesting Ewing sarcoma. The presence of an osteoid-producing tumor as evidenced by osteoblastic new bone formation will lead to the correct diagnosis.     

Recurrent parosteal osteosarcoma of the talus in a 2-year-old child

Parosteal osteosarcoma is an uncommon, low-grade malignant bone tumor and is found in an older age group than conventional osteosarcoma. We present a talar parosteal osteosarcoma that recurred twice in a 2-year-old child. To our knowledge, this is the youngest patient reported with a parosteal osteosarcoma. The talus is an unusual site for parosteal osteosarcoma. Inadequate resection due to a diagnosis of juxtacortical chondroma resulted in recurrence of the tumor. The age of the patient, the thick cartilaginous cap, and well-differentiated trabecular bone all contributed to the critical erroneous diagnosis.     

MRI detection of unsuspected vertebral injury in acute spinal trauma: incidence and significance

Objective. Multilevel spinal injury is well recognised. Previous studies reviewing the radiographs of spinal injury patients have shown an incidence of 15.2% of unsuspected spinal injury. It is recognised that magnetic resonance imaging (MRI) can identify injuries that are not demonstrated on radiographs. The objective of this study was to determine the incidence and significance of spinal injuries using MRI in comparison with radiographs. Design and patients. The radiographs and MR images of 110 acute spinal injury patients were reviewed independently of each other and the findings were then correlated to determine any unsuspected injury. Results. MRI detected vertebral body bone bruises (microtrabecular bone injury) in 41.8% of spinal injury patients which were not seen on radiographs. These bone bruises were best appreciated on sagittal short tau inversion recovery MR sequences and seen at contiguous and non-contiguous levels in relation to the primary injury. Conclusion. This level of incidence of bone bruises has not previously been appreciated. We recommend that patients undergoing MRI for an injured segment of the spine are better assessed by MRI of the entire spine at the same time to exclude further injury. Received: 17 April 2000 Revision requested: 19 June 2000 Revision received: 6 September 2000 Accepted: 27 November 2000