Analysis of 12q13-15 genes in parosteal osteosarcoma

The region q13-15 of chromosome 12 frequently is altered in human sarcomas, and several genes, such as SAS, CDK4, and MDM2, have been found to be amplified in bone and soft tissue sarcomas. These genes and their products were studied by quantitative polymerase chain reaction and immunohistochemical analysis in 25 parosteal osteosarcoma samples (22 Grades I or II, three dedifferentiated) to evaluate if the possible alterations detected of the genes on chromosome 12 could have a role in the development of this rare bone tumor. Immunohistochemical analysis was performed on formalin fixed, paraffin embedded tumor sections to evaluate CDK4 and MDM2 protein expression. To measure the degree of SAS and CDK4 gene amplification, quantitative polymerase chain reaction was done on deoxyribonucleic acid derived from the same samples. The results showed that CDK4 protein was expressed in 92% of the cases. Strong and uniform CDK4 and MDM2 immunoreactivity was found respectively in three of three and two of three dedifferentiated parosteal osteosarcomas. SAS and CDK4 genes were found to be amplified fourfold in two Grade II tumors and in one dedifferentiated tumor. These findings, which should be investigated further, might suggest a possible role of the chromosome 12 genes in the pathogenesis of parosteal osteosarcoma.

Dedifferentiated clear cell chondrosarcoma

Dedifferentiation, a change in the histologic character and clinical behavior of a tumor to a more immature and aggressive one, occurs in approximately 11% of all chondrosarcomas. The original lesion is usually a low-grade chondrosarcoma. Clear cell chondrosarcoma is a rare cartilaginous tumor of low-grade malignancy with a preference for the ends of long bones. It is usually curable by resection. Recurrence commonly follows inadequate surgery, and metastases to lung, brain, and bones can develop. However, dedifferentiation has not yet been described in association with clear cell chondrosarcoma. Three patients are described who were initially diagnosed as having clear cell chondrosarcoma of the femur. Two were treated with en bloc resection for a clear cell chondrosarcoma. One of these had an undifferentiated sarcoma in a local recurrence after 6 years. In the second, metastasis of the clear cell chondrosarcoma developed 5(1/2) years after surgery; autopsy revealed undifferentiated sarcoma in the lung, heart, and lumbar spine. The third patient had dedifferentiated clear cell chondrosarcoma at the time of resection following the biopsy diagnosis of clear cell chondrosarcoma. All three died with metastatic disease. These three patients represent three different manifestations of dedifferentiation-at initial diagnosis, at recurrence, and at metastasis. To our knowledge, this is the first description of dedifferentiation occurring in clear cell chondrosarcoma.

Extraabdominal desmoid tumor. A study of 83 cases

One hundred three patients with extraabdominal desmoid tumor were treated between 1970 and 1996 at the authors' institution. Among these, 15 patients were lost to followup and five were excluded because they had less than 1-year followup. The remaining 83 patients were followed up for a mean of 11.2 years. Thirty-seven (44.6%) patients experienced local recurrence on average 1.8 years after treatment. There was no difference in the incidence of recurrence between the two groups treated with surgery only (45.3%) or with adjuvant radiation therapy administered after inadequate surgical resection of the tumor margins (41.2%). Recurrence was not related to age, gender, and site. None of the 83 patients died of the disease. For recurrent but stable lesions, clinical observation alone may be considered.

Giant cell tumor of the bones of the hand and foot

BACKGROUND

Giant cell tumor of the small bones of the hand and foot is suspected of having some peculiar features compared with giant cell tumor in other sites. Moreover, it could share some features with other giant cell rich lesions involving the hand and foot, and this may affect the differential diagnosis. The aim of this study was to analyze the features of lesions such as these in the files of the Rizzoli Orthopedic Institute.

METHODS

The incidence of giant cell tumors of the bones of the hand and foot seen at the Rizzoli Orthopedic Institute over 50 years (1947-1997) was taken into consideration. There were 8 lesions of the hand and 21 of the foot. Clinical information and follow-up of the patients were studied and updated. Radiographs were studied and radiographic features analyzed. Histopathologic material was thoroughly reviewed and histologic features analyzed.

RESULTS

Although the location of tumor was helpful information, radiographic features were not specific. Giant cell tumors of the small bones of the hand and foot showed a predominance in females, younger patients and more aggressive behavior than giant cell tumors of large bones. The authors did not observe multicentricity or pulmonary metastases.

CONCLUSIONS

Because the radiographic features of giant cell tumor of the hand and foot overlap those of other giant cell rich lesions in these locations, histologic diagnosis is mandatory, although it may be difficult and require the establishment of diagnostic criteria for giant cell tumor. As this tumor tends to be more aggressive than other giant cell rich lesions, treatments of choice are aggressive curettage or resection.

Elastofibroma dorsi

It is often difficult to identify the characteristics of soft-tissue tumors of the chest wall. This paper describes the peculiarities of elastofibroma dorsi, a rare pseudotumor of this site, to exclude many dangerous misconceptions. During the period between 1987 and 1997, we treated nine patients with elastofibroma dorsi. In six patients, the lesion was unilateral and in three it was bilateral. All these lesions were excised and no evidence of local recurrence or shoulder disability was observed at the last clinical evaluation. Elastofibroma dorsi is a rare, slow-growing, pseudotumoral lesion of the soft tissues of the chest wall with a peculiar radiographic and histologic pattern.

Chondrosarcoma of the mobile spine: report on 22 cases

STUDY DESIGN

A retrospective review of 22 cases of chondrosarcoma arising from the mobile spine.

OBJECTIVE

To evaluate the role of oncologic and surgical staging in correlating management and outcome of chondrosarcoma involving the spine.

SUMMARY OF BACKGROUND DATA

Approximately 10% of chondrosarcomas arise from the mobile spine, occurring mainly in adults, particularly elderly men. The course of the disease depends on the aggressiveness of the tumor, but also is influenced by the management. Intralesional surgery is followed almost constantly by local recurrence even with adjuvant therapy.

METHODS

All charts, radiographs, and images were reviewed. The composite information provided by this review allowed for oncologic and surgical staging of the reviewed cases. According to Enneking criteria, the surgical procedures were defined as curettage (piecemeal excision) or en blocexcision. The margins were submitted to histologic study and reported as intralesional, marginal, or wide. - As primary management, 10 intralesional curettages (follow-up period, 2-119 months; average, 61 months) and 12 en bloc excisions (follow-up period, 39-207 months; average, 97 months) were performed. A total of 33 procedures were performed, including the management of the recurrences (18 curettages and 15 en bloc excisions: one for soft tissue recurrence). A clinical and radiographic follow-up period of of 2 to 236 months (average, 81 months; minimal follow-up period for survivors, 30 months; average follow-up period for survivors, 115 months) was available for all the patients.

RESULTS

Three recurrences occurred in 14 patients treated by en bloc excision at onset or for recurrence, two in cases of histologically proven contaminated or intralesional margins. All but one patient were alive at final follow-up evaluation. Conversely, all the patients treated by one or more curettages (with or without adjuvant radiation therapy) had at least one recurrence, and 8 of 10 of these patients died of the disease. At final follow-up evaluation, nine patients had died of the disease; nine were continuously disease free (but one had died of another unrelated malignancy); and four were symptom free after management for recurrences (one was found alive 155 months after a soft-tissue metastasis en-bloc excision).

CONCLUSIONS

En bloc excision, with wide or marginal histologic margins, is the suggested management for chondrosarcomas of the spine. Early diagnosis and careful surgical staging and planning are necessary for conducting adequate management. However, tumor contamination of the specimen margins, even in a small area, or spreading of the tumor myxoid content can worsen the prognosis.

Neoadjuvant chemotherapy for peripheral malignant neuroectodermal tumor of bone: recent experience at the istituto rizzoli

PURPOSE

The results achieved in 44 patients with nonmetastatic peripheral neuroectodermal tumor (PNET) of bone treated with neoadjuvant chemotherapy are reported.

PATIENTS AND METHODS

A six-drug regimen of chemotherapy (vincristine, doxorubicin, dactinomycin, cyclophosphamide, ifosfamide, and etoposide) was administered to all patients. Local treatment consisted of surgery in 20 patients, surgery followed by radiotherapy in 13, and radiotherapy only in 11.

RESULTS

At a mean follow-up of 4.5 years (range, 2 to 7 years), 23 patients (52%) remain event-free, 20 have relapsed (45%), and one has died of chemotherapy-related toxicity. The 5-year event-free survival and overall survival were 54.2% and 62.7%, respectively. To assess the prognostic significance of neural differentiation in the family of Ewing's sarcoma, these results have been compared with the outcomes of 138 concomitant patients with typical Ewing's sarcoma (TES) who were treated according to the same protocol. Of these, 103 (75%) remained continuously event-free, 34 (24%) relapsed, and one died of chemotherapy-related toxicity. It follows that PNET patients treated with this chemotherapy regimen have a significantly worse prognosis than typical ES patients (5-year event-free survival, 54.2% v 70.6%, P <.012; 5-year overall survival, 62.7% v 78.3%, P <.002).

CONCLUSION

The authors conclude that studies into new adjuvant therapy for Ewing's sarcoma modulated according to risk of relapse should also consider neural differentiation as a risk factor.

Prognostic factors in nonmetastatic Ewing's sarcoma of bone treated with adjuvant chemotherapy: analysis of 359 patients at the Istituto Ortopedico Rizzoli

PURPOSE

The identification of prognostic factors in patients with nonmetastatic Ewing's sarcoma could allow the use of risk-adapted therapeutic strategies of treatment.

PATIENTS AND METHODS

Data on 359 patients with nonmetastatic Ewing's sarcoma of bone treated at a single institution between January 1979 and April 1995 were retrospectively considered. The influence of clinical, hematologic, therapeutic, and histologic parameters on event-free survival was assessed.

RESULTS

By univariate analysis, the following features were found to be associated with a poor prognosis: male sex (P <.02), age older than 12 years (P <.006), fever (P <.0001), anemia (P <.0025), high serum lactate dehydrogenase (LDH) level (P <.0001), axial location (P <.04), radiation therapy only for local control (P <.009), type of chemotherapy regimen (P <.0001), and poor chemotherapy-induced necrosis (P <.001). After multivariate analysis, the adverse independent prognostic factors were male sex (P <.04), age older than 12 years (P <.001), fever (P <.0002), anemia (P <.02), high serum LDH level (P <.0003), axial location (P <.02), and type of chemotherapy regimen (P <.0003). When the multivariate analysis was restricted to surgically treated patients, the adverse independent prognostic factors were poor chemotherapy-induced necrosis (P <.0001), fever (P <.015), anemia (P <.02), and high serum LDH level (P <.025).

CONCLUSION

The prognosis in cases of nonmetastatic Ewing's sarcoma is influenced by many different clinical and hematologic variables, all of which are to be considered when patients are being stratified according to the risk of relapse. In surgically treated patients, the most important prognostic factor is chemotherapy-induced necrosis.

Synovial sarcoma: identification of low and high risk groups

BACKGROUND

Synovial sarcoma, one of the most common soft tissue sarcomas that occur in adolescents and young adults, is generally viewed and treated as a high grade sarcoma. However, the authors' own experience and some previous studies have indicated that it has a wide spectrum of biologic behavior and that low and high risk subgroups of patients with synovial sarcoma can be identified.

METHODS

A total of 121 consecutive patients with synovial sarcoma (including 66 males and 55 females ages 9-74 years), treated primarily or secondarily at 2 large referral centers for musculoskeletal tumors, were included in a statistical analysis conducted to identify independent prognostic factors.

RESULTS

There were local recurrences in 38 patients (31%), usually after inadequate primary surgery outside the referral centers; 64 patients (54%) developed metastasis, primarily to the lungs. The estimated 5-, 10-, and 15-year survival rates were 60%, 50%, and 45%, respectively (the mean follow-up for surviving patients was 9.8 years, with a range of 1-30 years). In multivariate analysis, independent risk factors for local recurrence included larger tumor size and primary surgical resection outside the referral center. Independent risk factors for metastasis were older patient age, tumor with poor histologic differentiation, and tumor necrosis. For tumor-related death, the independent risk factors were older patient age, tumor with poor histologic differentiation, and larger tumor size. Local recurrence was associated with a 3.66-fold increased risk of tumor-related death. A low risk group (patient age <25 years, tumor size <5 cm, and no histologic evidence of poorly differentiated tumor) with 88% overall disease free survival was identified, as was a high risk group (patient age > or = 25 years, tumor size > or = 5 cm, and poorly differentiated tumor) with 18% overall disease free survival (P < 0.001).

CONCLUSIONS

The identification of low and high risk synovial sarcoma patients indicates that synovial sarcomas are not uniformly high grade tumors. It also indicates that treatment strategies should be modified for these risk groups. Adequate primary surgery is essential to both local control and outcome for synovial sarcoma patients.

Genetic imbalances in 67 synovial sarcomas evaluated by comparative genomic hybridization

We used comparative genomic hybridization (CGH) to evaluate DNA sequence copy number changes in 67 synovial sarcomas of both monophasic and biphasic histological subtypes. Changes (mean among aberrant cases: 4.7 aberrations/tumor; range: 1-17), affecting most often entire chromosomes or chromosome arms, were detected in 37 sarcomas (55%). Gains and losses were distributed equally, but different chromosomes were affected with variable frequencies. The most frequent aberrations, each detected in 9-11 of 67 tumors, were gain of 8q and gain at 12q (12q14-15 and 12q23-qter), loss of 13q21-31, and loss of 3p. Other frequent changes (in 7 or 8 cases) included gains at 2p, 1q24-31, and 17q22-qter, and losses at 3cen-q23 and 10q21. High-level amplifications were seen in 7 cases. A total of 16 regions were detected. Two of them, 8p12-qter and 21q21-qter, seen in 4 and 2 tumors, respectively, were recurrent. No aberrations specific to histological subtype were identified. However, genetic changes in the monophasic tumors were more complex and numerous (mean among aberrant cases: 5.3 aberrations/tumor; range: 1-17) than in the biphasic tumors (mean: 2.5 aberrations/tumor; range: 1-5), and high-level amplifications occurred more frequently. All but 1 of the sarcomas showing high-level amplification were of the monophasic subtype. These findings may reflect differences in the pathogenesis and biological behavior of both histological subtypes of synovial sarcoma.

Giant cell reparative granuloma of the phalanx of the hand with aggressive radiographic features

This report describes a giant cell (reparative) granuloma in the proximal phalanx of the third finger of the right hand in a 52-year-old man. Radiographically it showed aggressive features with bony permeation, breaking of the cortex, and soft tissue extension. These features suggested a malignant lesion. Histology was characteristic of giant cell reparative granuloma. This lesion, along with aneurysmal bone cyst and giant cell tumor in the small bones of hand and foot, occasionally may show aggressive features mimicking a malignant lesion.

Osteosarcoma of the bones of the foot--an easily misdiagnosed malignant tumor

OBJECTIVE

To evaluate the frequency of osteosarcoma involving the foot and determine the clinical outcome of affected patients.

MATERIAL AND METHODS

We retrospectively reviewed the cases of osteosarcoma encountered between 1911 and 1992 at the Rizzoli Orthopedic Institute. In particular, we analyzed whether common clinical, radiographic, or histologic features could lead to a correct diagnosis of osteosarcoma of the foot.

RESULTS

The bones of the foot were the primary site of osteosarcomas in 12 cases--0.6% of the entire series of such tumors at our institution during the study period. The mean age of the patients was 33 years. Initial symptoms were usually pain and swelling. Late diagnosis was common; the mean time interval between the first symptoms and diagnosis was 28 months. Misdiagnoses occurred in 6 of the 12 cases (50%): osteoblastoma, chondroblastoma, chondrosarcoma, osteoid osteoma, desmoid fibroma, and osteomyelitis were, respectively, the initial diagnoses. Histologically, 5 of the 12 tumors (42%) were low-grade lesions. Four of the seven patients with a high-grade tumor died of metastatic disease after a mean survival of 50 months. Eight patients are alive with no evidence of disease after a mean follow-up of 162 months.

CONCLUSION

When a painful swelling in a bone of the foot is observed, even if numerous benign conditions (such as fractures, infections, or benign bone tumors) are far more likely to occur, osteosarcoma must be ruled out to avoid delays in the treatment. Osteosarcomas of the foot may easily be misdiagnosed, especially because they almost always occur in adults, in contrast to osteosarcomas in general. High-grade tumors of the foot are as aggressive as other osteosarcomas and should be managed accordingly--with use of a safe-margins surgical procedure and chemotherapy.

Intra-articular hyaluronic acid in the treatment of osteoarthritis of the knee: clinical and morphological study

OBJECTIVE

To evaluate, in a pilot, open clinical trial on 40 patients with knee osteoarthritis, the structural changes in the synovial membrane and cartilage following treatment with intra-articular hyaluronic acid (HA-Hyalgan).

METHODS

The structural effects of HA given as 5 weekly injections (20 mg/2 ml once a week for 5 weeks), were evaluated by microarthroscopy and morphological analysis of biopsy samples taken at baseline and after 6 months, under blind conditions. Clinical efficacy was also evaluated using visual analogue scales for pain and functional parameters.

RESULTS

At 6 months, the microarthroscopic evaluation indicated that the majority of the patients (60%) showed no changes compared to baseline, while 32.5% of the patients showed improvement in the grading and/or extension of cartilage lesions and 7.5% showed a worsened condition. These changes were accompanied by a statistically significant reduction in the synovial inflammation (p = 0.001). The results were confirmed by morphological examination of the cartilage and synovial membrane. At 6 months compared to baseline, a statistically significant reconstitution of the superficial amorphous layer of the cartilage (p = 0.0039), an improvement in the chondrocyte density (p = 0.0023) and vitality (p = 0.05), and a statistically significant reduction in synovial inflammation (p = 0.0001) accompanied by a significant increase in the synovial repair process (p = 0.0001) were observed. Significant and long lasting improvement in pain and joint mobility were also seen after HA treatment. Joint effusion, when present, was reduced. The treatment was well tolerated.

CONCLUSION

Hyalgan represents a useful therapy for knee OA, with long-lasting symptomatic efficacy and potential positive effects on joint tissues. Other studies, in particular placebo-controlled studies, are warranted to confirm these promising results observed on joint tissues.

Classification of bone tumors

The classification of bone tumors relies on the cytologic features and products of tumor cells. This classification is reproducible and accepted by pathologists, oncologic surgeons and oncologists. Chondrogenic tumors are the second largest group of bone tumors. Their histologic pattern suggests a relationship to hyaline cartilage. Exostoses, or osteochondromas, represent about 1/3 of chondrogenic lesions. Chondromas are hyaline cartilage tumors which can be found centrally or subperiosteally; they may contain some calcifications and/or ossifications. Chondroblastomas are tumors whose cells produce, at least focally, a matrix similar to hyaline cartilage. Histology of chondromyxoid fibromas shows large or small areas where proliferating cells produce a matrix resembling the hyaline cartilage. Chondosarcomas are tumors whose malignant cells produce a cartilaginous matrix. Most of them occur in previously normal bones; they are classified as conventional or primary chondrosarcomas. Secondary chondrosarcomas result from the malignant transformation of a benign cartilaginous lesion less commonly enchondromas and most commonly osteocartilaginous exostoses, or osteochondromas. Less common variants include dedifferentiated, mesenchymal and clear cell chondrosarcomas. Osteogenic tumors are the third largest group of bone tumors, with osteosarcomas being the most frequent type. The most important criterion for a tumor to be considered an osteosarcoma is that the malignant tumor cells must produce a recognizable osteoid matrix, at least focally. Osteosarcomas are divided into three groups: osteoblastic, chondroblastic and fibroblastic, according to the dominant histologic feature. Osteosarcomas can be multifocal, synchronous or metachronous; they are also classified by the histologic grade of malignancy. Pathologically low grade lesions, which are clinically indolent, are generally known as low grade central and parosteal osteosarcomas.

Prognostic significance of cyclin expression in human osteosarcoma

To evaluate the distribution of cyclin protein expression, in relation to cell proliferation rate and clinical behavior, an immunohistochemical study was performed on 92 tumor samples of patients with high grade osteosarcoma (OS). A large cyclin A- and cyclin E-positive fraction was found respectively in 59% and 47% of the osteosarcomas, while immunostaining for cyclin D1 was weak or absent in most tumor samples. A positive, statistically significant correlation was found between A and E cyclins and Ki67 expression (p<0.001). Disease-free survival (DFS) analysis included 69 of the 92 patients. A significantly higher probability of metastasis was seen in patients lacking cyclin D1 compared to those in which cyclin D1 was positive (p<0.01). Conversely, patients with >40% of cyclin A-positive cells relapsed more frequently than those with <40% of cyclin A-positive cells (p<0.05). The multivariate analysis demonstrated that cyclin A had a lower predective risk in terms of disease-free survival as opposed to the loss of cyclin D1 that is considered a powerful prognostic factor.

Bizarre parosteal osteochondromatous proliferation of bone

A 47-year-old man presented with a painless mass of 7 months' duration, on the plantar aspect of the great toe of the right foot. Radiographs and CT images initially suggested an osteochondroma arising from the proximal phalanx of the great toe but there was no continuity between the medullary canal of the phalanx and the lesion. The mass was excised and a histological diagnosis of bizarre parosteal osteochondromatous proliferation of bone (Nora's disease) was made. The aggressive growth of this lesion may clinically suggest a neoplasm. Histological features, however, are those of a reactive lesion.

Predictive factors of histologic response to primary chemotherapy in osteosarcoma of the extremity: study of 272 patients preoperatively treated with high-dose methotrexate, doxorubicin, and cisplatin

PURPOSE

In osteosarcoma of the extremity, a strong correlation between chemotherapy-induced necrosis and prognosis has been reported. The aim of this study was to investigate the possible factors that influence histologic response to primary chemotherapy.

PATIENTS AND METHODS

In 272 patients with high-grade osteosarcoma of the extremity preoperatively treated with high-dose methotrexate (HDMTX), cisplatin (CDP), and doxorubicin (ADM), the histologic response to chemotherapy was evaluated and graded as complete (no viable tumor cells) or incomplete (persistence of viable tumor cells). Several factors, such as metastatic disease to the lung at diagnosis, sex, age, site and tumor volume, histologic subtype, serum alkaline phosphatase, lactate dehydrogenase (LDH), and methotrexate (MTX) pharmacokinetics were investigated to test their predictive significance on histologic response.

RESULTS

Fifty-one patients with localized disease (20.6%) and none of the 25 patients with metastatic disease at presentation had a complete histologic response (P = .006). After multivariate analysis, performed on patients with localized disease only, MTX serum peak (> or = 700 micromol/L) and histologic subtype were proven to be significant predictive factors of histologic response. A complete response was seen in 28.8% of patients with 700 micromol/L or greater MTX serum levels and in 9.9% of those patients with lower levels (P = .001). The chondroblastic subtype was less responsive (6.1% of complete response), compared with the osteoblastic (16.3%), fibroblastic (33.3%), and telangiectatic (42.3%).

CONCLUSION

Patients with metastatic osteosarcoma and localized chondroblastic osteosarcoma have a reduced chemosensitivity to primary chemotherapy with MTX, CDP, and ADM. MTX serum peak significantly influences tumor necrosis. A dose adaptation of MTX is recommended to obtain a serum peak of 700 micromol/L or greater when MTX is infused in 6 hours.

Resection surgery in the treatment of vertebral tumors

With the purpose of clarifying the limits of resection surgery (en bloc excision) for the treatment of bone tumors of the spine, the authors report the indications and results of 43 operations. This series was homogeneous in terms of oncological and surgical staging, as well as with regard to surgical method used and anaesthesiology. Three different types of surgery were performed: en bloc resection of tumors of the body (sectors 5-9 or 4-8 depending on the WBB staging system), of the posterior arch (sectors 10-3) or characterized by eccentric growth (sectors 2-5 or 8-11). The surgical margins were histologically studied in all of the cases: based on the evaluation and on histological diagnosis further chemo- and/or radiation therapy were decided on. Long-term follow-up was obtained for all of the cases (from 6 to 153 months, mean 30 months; 26 cases followed for more than 24 months). Six of the patients died as a result of the disease from 10 to 28 months after resection. There were 4 local recurrences, 4 pulmonary metastases, and 5 metastatic disseminations to the skeleton and to other tissues observed in 11 patients. At final follow-up 33 patients (77%) were thus disease-free (32 continually), in excellent condition, and capable of living a normal life. Complications and treatment are also reported. A careful study of the neoplasm, an appropriate selection of the patients based on diagnosis and histological staging, a knowledge of the natural progression of bone neoplasms and of the surgical anatomy of the vertebral column, the application of suitable measures of anaesthesiological control, allow for a correct cost/benefit evaluation of this type of surgery as compared to oncological methods that are less effective but more diffused. On the basis of these considerations indications for en bloc resection in tumors of the spine are defined.

Altered G1 phase regulation in osteosarcoma

Alterations in the normal cell cycle lead to abnormal cell proliferation and to tumor development. To explore the role of the cyclin D/Cdk4 complex and the retinoblastoma protein (pRb) in the growth and spread of osteoblastic osteosarcoma (OS), 40 tumor samples were selected. In 17 of these cases, lung metastases occurred during follow-up. Expression of pRb, cyclin D1 and its catalytic subunit, Cdk4, was studied by immunohistochemistry and immunoblotting. As controls, non-neoplastic tissues surrounding the tumor were used. The expression level and pattern were compared to clinical outcome. Cdk4 was over-expressed in 80% of OS, independently of clinical outcome, and showed an intense and uniform distribution in tumor cells compared to normal cells. However, co-immunoprecipitation of Cdk4 with cyclin D1 revealed low levels of cyclin D/Cdk4 complex; 20 of 40 OS examined had a negative or minimal immunostaining for active pRb. The probability of relapse was significantly higher in pRb-negative than in the -positive patients (p < 0.05). The ratio of unphosphorylated/hyperphosphorylated pRb was lower in relapsed patients than in patients with no evident disease, though the difference was not statistically significant. High levels of pRb/cyclin D1 were found in all samples exhibiting functional pRb expression. Our results show that G1 phase deregulation is involved in formation and development of OS. The expression levels of both pRb and cyclin D1 had a clear correlation with clinical outcome, suggesting that these parameters could be used as prognostic markers.