Sestamibi and FDG-PET scans to support diagnosis of jaw osteonecrosis

Vertebral Body Osteonecrosis Mimicking Malignant Disease on 18F-FDG PET

ABSTRACT

We report a case of vertebral osteonecrosis after chemotherapy in a 24-year-old man with non-Hodgkin lymphoma, with transient avidity on 18F-FDG PET initially misinterpreted as recurrent extranodal disease. The patient demonstrated a partial metabolic response on midtreatment restaging PET; however, posttreatment PET showed an increase in uptake in T4 and T5 vertebrae, interpreted as recurrent vertebral disease. Repeat PET performed 9 days later showed resolution of thoracic vertebral uptake without interval treatment. On follow-up PET study, thoracic vertebrae demonstrated photopenia with sclerosis on CT, concerning for osteonecrosis. MRI features were concordant with this diagnosis.

Do various imaging modalities provide potential early detection and diagnosis of medication-related osteonecrosis of the jaw? A review

OBJECTIVE

Patients with medication-related osteonecrosis of the jaw (MRONJ) often visit their dentists at advanced stages and subsequently require treatments that greatly affect quality of life. Currently, no clear diagnostic criteria exist to assess MRONJ, and the definitive diagnosis solely relies on clinical bone exposure. This ambiguity leads to a diagnostic delay, complications, and unnecessary burden. This article aims to identify imaging modalities' usage and findings of MRONJ to provide possible approaches for early detection.

METHODS

Literature searches were conducted using PubMed, Web of Science, Scopus, and Cochrane Library to review all diagnostic imaging modalities for MRONJ.

RESULTS

Panoramic radiography offers a fundamental understanding of the lesions. Imaging findings were comparable between non-exposed and exposed MRONJ, showing osteolysis, osteosclerosis, and thickened lamina dura. Mandibular cortex index Class II could be a potential early MRONJ indicator. While three-dimensional modalities, CT and CBCT, were able to show more features unique to MRONJ such as a solid type periosteal reaction, buccal predominance of cortical perforation, and bone-within-bone appearance. MRI signal intensities of vital bones are hypointense on T₁WI and hyperintense on T₂WI and STIR when necrotic bone shows hypointensity on all T₁WI, T₂WI, and STIR. Functional imaging is the most sensitive method but is usually performed in metastasis detection rather than being a diagnostic tool for early MRONJ.

CONCLUSION

Currently, MRONJ-specific imaging features cannot be firmly established. However, the current data are valuable as it may lead to a more efficient diagnostic procedure along with a more suitable selection of imaging modalities.

Calcium Phosphate Ceramics Can Prevent Bisphosphonate-Related Osteonecrosis of the Jaw

Bisphosphonate-associated osteonecrosis of the jaw (BRONJ), a post-surgical non-healing wound condition, is one of the most common side effects in patients treated with nitrogen-containing bisphosphonates. Its physiopathology has been related with suppression of bone turnover, of soft tissue healing and infection. Biphasic calcium phosphates (BCP) are used as a drug delivery vehicle and as a bone substitute in surgical wounds. Due to their capacity to adsorb zoledronate, it was hypothesized these compounds might have a protective effect on the soft tissues in BRONJ wounds. To address this hypothesis, a reproducible in vivo model of BRONJ in Wistar rats was used. This model directly relates chronic bisphosphonate administration with the development of osteonecrosis of the jaw after tooth extraction. BCP granules were placed in the alveolus immediately after tooth extraction in the test group. The animals were evaluated through nuclear medicine, radiology, macroscopic observation, and histologic analysis. Encouragingly, calcium phosphate ceramics were able to limit zoledronate toxicity in vivo and to favor healing, which was evidenced by medical imaging (nuclear medicine and radiology), macroscopically, and through histology. The studied therapeutic option presented itself as a potential solution to prevent the development of maxillary osteonecrosis.

Clinical Nononcologic Applications of PET/CT and PET/MRI in Musculoskeletal, Orthopedic, and Rheumatologic Imaging

OBJECTIVE

With improvements in PET/CT and PET/MRI over the last decade, as well as increased understanding of the pathophysiology of musculoskeletal diseases, there is an emerging potential for PET as a primary or complementary modality in the management of rheumatologic and orthopedic conditions.

CONCLUSION

We discuss the role of PET/CT and PET/MRI in nononcologic musculoskeletal disorders, including inflammatory and infectious conditions and postoperative complications. There is great potential for an increased role for PET to serve as a primary or complementary modality in the management of orthopedic and rheumatologic disorders.

Musculoskeletal Pitfalls on Fluorodeoxyglucose F 18 PET-Computed Tomography: Pictorial Review

A wide range of musculoskeletal processes can demonstrate increased uptake on PET-computed tomography (CT) with fluorodeoxyglucose (FDG) F 18, including reactive, benign neoplastic, inflammatory, traumatic, posttreatment, and arthritic conditions that may mimic malignancy. In addition, physiologic causes of increased FDG uptake such as asymmetric muscle use and presence of brown fat can lead to increased FDG uptake and potential false-positive results. This article presents various case examples of non-malignant musculoskeletal hypermetabolism on 18F-FDG PET-CT and describes useful tools to avoid the potential pitfall of misinterpreting these as malignancy.

Disease- and Treatment-related Complication on F-18-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Oncology Practice: A Pictorial Review

F-18-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) is routinely performed in oncology patients for various indications including staging, restaging, recurrence detection, and treatment response evaluation. Many disease- and treatment-related complications can be incidentally detected on PET/CT, which may be due to the complication of radiotherapy, chemotherapy, intervention, or primary tumor itself. Some of these complications could be life threatening and need urgent intervention. Therefore, these incidental findings should be recognized on PET/CT and immediately informed to the treating physicians if required urgent intervention.

18F-FDG PET/CT, 99mTc-MIBI, and MRI in the prediction of outcome of patients with multiple myeloma: a comparative study

PURPOSE

The aim of this study was to compare the relative contribution of 18F-FDG PET/CT, 99mTc-MIBI, and MRI in predicting progression-free survival (PFS) and overall survival (OS) in multiple myeloma (MM) patients.

PATIENTS AND METHODS

Thirty-three newly diagnosed MM patients had been evaluated in a previous study by 18F-FDG PET/CT, 99mTc-MIBI, and spine and pelvis MRI reporting focal lesions and diffuse bone marrow involvement. Twenty-seven patients were then subjected to a mean follow-up period of 58 months, whereas 6 patients were lost.

RESULTS

18F-FDG PET/CT, 99mTc-MIBI, and MRI were positive in 26, 24, and 22 patients, respectively, showing diffuse bone marrow involvement in 12, 21, and 17 patients and a total of 185, 56, and 39 focal lesions, respectively. At follow-up, 18 patients showed complete or partial remission, whereas 9 patients developed progressive disease, 7 of which died of myeloma. Univariate and subsequent multivariate analysis showed that F-FDG PET/CT focal uptake and Tc-MIBI focal and diffuse uptake predicted PFS (P = 0.0006), whereas 18F-FDG PET/CT focal uptake and 99mTc-MIBI focal uptake predicted OS (P = 0.0010). Although MRI diffuse pattern predicted PFS at univariate analysis (P = 0.0376), it was not retained in the model at multivariate analysis. Receiver operating characteristic curve analysis showed that the number of focal lesions best discriminating for PFS and OS prediction was 4 and 11 for 18F-FDG PET/CT and 2 in both cases for 99mTc-MIBI, respectively. By Kaplan-Meier analysis and log-rank testing, PFS and OS at follow-up were significantly better in patients showing a number of focal lesions at F-FDG PET/CT or Tc-MIBI lower than the respective cutoff (P = 0.03, P = 0.004, and P < 0.0001, respectively). Finally, PFS was significantly better in patients showing absent/faint diffuse Tc-MIBI uptake than in those having moderate/intense diffuse uptake (P = 0.0012).

CONCLUSIONS

18F-FDG PET/CT and 99mTc-MIBI may be useful in predicting PFS and OS in myeloma patients.

Diagnosis and management of osteonecrosis of the jaw: a systematic review and international consensus

This work provides a systematic review of the literature from January 2003 to April 2014 pertaining to the incidence, pathophysiology, diagnosis, and treatment of osteonecrosis of the jaw (ONJ), and offers recommendations for its management based on multidisciplinary international consensus. ONJ is associated with oncology-dose parenteral antiresorptive therapy of bisphosphonates (BP) and denosumab (Dmab). The incidence of ONJ is greatest in the oncology patient population (1% to 15%), where high doses of these medications are used at frequent intervals. In the osteoporosis patient population, the incidence of ONJ is estimated at 0.001% to 0.01%, marginally higher than the incidence in the general population (<0.001%). New insights into the pathophysiology of ONJ include antiresorptive effects of BPs and Dmab, effects of BPs on gamma delta T-cells and on monocyte and macrophage function, as well as the role of local bacterial infection, inflammation, and necrosis. Advances in imaging include the use of cone beam computerized tomography assessing cortical and cancellous architecture with lower radiation exposure, magnetic resonance imaging, bone scanning, and positron emission tomography, although plain films often suffice. Other risk factors for ONJ include glucocorticoid use, maxillary or mandibular bone surgery, poor oral hygiene, chronic inflammation, diabetes mellitus, ill-fitting dentures, as well as other drugs, including antiangiogenic agents. Prevention strategies for ONJ include elimination or stabilization of oral disease prior to initiation of antiresorptive agents, as well as maintenance of good oral hygiene. In those patients at high risk for the development of ONJ, including cancer patients receiving high-dose BP or Dmab therapy, consideration should be given to withholding antiresorptive therapy following extensive oral surgery until the surgical site heals with mature mucosal coverage. Management of ONJ is based on the stage of the disease, size of the lesions, and the presence of contributing drug therapy and comorbidity. Conservative therapy includes topical antibiotic oral rinses and systemic antibiotic therapy. Localized surgical debridement is indicated in advanced nonresponsive disease and has been successful. Early data have suggested enhanced osseous wound healing with teriparatide in those without contraindications for its use. Experimental therapy includes bone marrow stem cell intralesional transplantation, low-level laser therapy, local platelet-derived growth factor application, hyperbaric oxygen, and tissue grafting.

What is the role of positron emission tomography in osteonecrosis of the jaws?

PURPOSE

Bisphosphonate-related osteonecrosis of the jaw (BP-ONJ) has become an associated side effect of BP therapy and several imaging modalities have been studied to show an ability to detect clinical disease. Because most patients at the authors' university hospital who develop BP-ONJ also undergo concurrent positron emission tomographic (PET) scanning, the authors investigated the utility of PET scans for diagnosis of BP-ONJ.

PATIENTS AND METHODS

A retrospective chart review was performed of patients whose PET scans were acquired within 1 year of their BP-ONJ diagnosis (1998 through 2006). BP-ONJ was defined as intraoral exposure of the maxilla or mandible in patients on BPs and not given radiation to that area. This was performed at a university hospital with oncologic patients treated with BPs. All PET scans in this study were secondarily reviewed by a single expert reader for internal consistency (T.B.B.). A detailed timeline of the course of BP-ONJ was constructed by the review of medical records for each patient and the relation of each patient's PET scan results to that patient's BP-ONJ disease was evaluated. Data analysis was a descriptive analysis of PET scan findings in this patient population.

RESULTS

Of the 25 patients studied, 5 were excluded for insufficient clinical or radiologic data. Of the 20 remaining patients (16 male, 4 female), 46 PET scans were performed and showed 53 areas of enhancement. Many patients had multiple PET scans performed while experiencing exposed bone, and 5 of these patients had alternating positive and negative scans with exposed bone, resulting in 13 patients with positive enhancement on a scan with exposed bone and 9 patients with no enhancement on a scan with exposed bone. Of the 13 patients with PET enhancement, 4 had signs of clinical infection documented at the time of examination. Sensitivity, specificity, and accuracy of PET scanning for BP-ONJ were 43%, 19%, and 62%, respectively. There were 7 patients with PET scans performed after clinical resolution of their exposed bone and 6 of those had no enhancement.

CONCLUSION

The purpose of this study was to report findings on PET scanning for patients with BP-ONJ. Although PET scans are useful in oncology, the present findings do not support their routine use for exclusively diagnosing or following cases of BP-ONJ.

Imaging appearances for recurrent nasopharyngeal carcinoma and post-salvage nasopharyngectomy

Nasopharyngeal carcinoma (NPC) is a head and neck neoplasm that occurs in endemic numbers among people of southern Chinese descent. External beam radiation to the nasopharyngeal bed and primary draining lymph node echelons is the mainstay of treatment with concurrent cisplatin-based chemotherapy for more advanced disease. Detection of residual and/or recurrent NPC has important clinical implications, as salvage protocols are available. The review aims to increase awareness of the imaging features of NPC recurrences at local and distant sites using computed tomography (CT), magnetic resonance imaging (MRI), and positron-emission tomography (PET). Important changes in imaging seen in patients after nasopharyngectomy are also discussed.

Skeletal complications of bisphosphonate use: what the radiologist should know

Bisphosphonates are widely used for prevention of fractures in patients at risk, mainly in the presence of osteoporosis and bone metastases. A number of adverse effects of prolonged bisphosphonate treatment have emerged. We would like to highlight the skeletal complications from which a radiologist may be the first healthcare professional to recognise the association with bisphosphonate therapy. We illustrate these complications (namely osteonecrosis of the jaw and less well-known atypical femoral shaft fractures), presenting radiological findings in our patients. Recommendations for safer use of bisphosphonates are included in the conclusion of our review.

Fractal dimension evaluation of cone beam computed tomography in patients with bisphosphonate-associated osteonecrosis

OBJECTIVES

The aim of this study was to (1) evaluate the fractal dimension (FD) in regions of the mandible on cone beam CT (CBCT) images of patients with bisphosphonate-associated osteonecrosis of the jaws (BP-ONJ) and (2) to select the most suitable region of interest (ROI) for further study on detection of bone alterations associated with bisphosphonates.

METHODS

CBCT images of patients with BP-ONJ were included with matched controls. Values of FD were compared between groups. Selected ROIs were: ROI-1 - below the mandibular foramen; ROI-2 - above the mandibular foramen; ROI-3 - anterior to the mental foramen; ROI-4 - above the mandibular canal. The area of bone exposure was included as ROI-5. The results were analysed using generalized estimating equations and conditional logistic regression.

RESULTS

There were 36 patients (67% female) with a mean age of 60.7 years. The mean FDs were: ROI-1 - 1.678 for controls and 1.673 for patients (P = 0.81); ROI-2 - 1.657 for controls and 1.653 for patients (P = 0.78); ROI-3 - 1.661 for controls and 1.684 for patients (P = 0.17); and ROI-4 - 1.670 for controls and 1.698 for patients (P = 0.03). The value of the FD in the area of exposed bone was the highest (1.729). The odds of being a BP-ONJ patient vs being a control was six times as high for individuals with a higher FD score at ROI-4, although the confidence interval was quite wide owing to the small sample size.

CONCLUSION

In this preliminary study, BP-ONJ patients had higher FD values than controls at regions close to the alveolar process. The results suggest that FD is a promising tool for detection of bone alterations associated with BP-ONJ.

Bisphosphonates and oral health: primer and an update for the practicing surgeon

Oral and intravenous bisphosphonates have been in clinical use for two decades for the treatment of patients with malignancy, osteoporosis, and other diseases affecting bone metabolism. The purpose of this article is to review the features of these drugs, their effect on the diseases they treat, the oral findings associated with their use, and the assessment of osteonecrosis incidence, pathophysiology, with some insights into treatment.

Pathophysiology of atypical femoral fractures and osteonecrosis of the jaw

In recent years, atypical femoral fractures and osteonecrosis of the jaw have emerged as potential complications of long-term bisphosphonate therapy; osteonecrosis of the jaw has also been reported in patients receiving high doses of denosumab. The pathophysiology of both conditions is poorly defined, and the underlying mechanisms are likely to differ. The initiation of atypical fractures in the lateral femoral shaft suggests that reduced tensile strength, possibly secondary to alterations in the material properties of bone resulting from low bone turnover, may be an important pathogenetic factor. Osteonecrosis of the jaw is characterised by infection, inflammation, bone resorption and bone necrosis, but the sequence in which these occur has not been established. However, the observation that bone resorption occurs in close proximity to microbial structures suggests that infection may be the most important trigger, often as a result of dental disease. Other possible pathogenetic factors include suppression of bone turnover, altered immune status and adverse effects of bisphosphonates on the oral mucosa.

Differentiating osteoradionecrosis from nasopharyngeal carcinoma tumour recurrence using ⁹⁹Tcm-sestamibi SPECT/CT

Osteoradionecrosis (ORN) of the base of skull is a known complication of external beam radiotherapy in the treatment of nasopharyngeal carcinoma, and is widely believed to be sequelae of radiation-induced endarteritis, leading to cellular death and fibrosis. Differentiating ORN from tumour recurrence is challenging and has direct clinical implications. We present a case where (99)Tc(m)-sestamibi SPECT/CT was used to differentiate ORN from tumour recurrence and in which prior imaging using bone scintigraphy and fluorodeoxyglucose PET/CT were equivocal.

Causes and imaging features of false positives and false negatives on F-PET/CT in oncologic imaging

BACKGROUND: 18F-FDG is a glucose analogue that is taken up by a wide range of malignancies. 18F-FDG PET-CT is now firmly established as an accurate method for the staging and restaging of various cancers. However, 18F-FDG also accumulates in normal tissue and other non-malignant conditions, and some malignancies do not take up F18-FDG or have a low affinity for the tracer, leading to false-positive and false-negative interpretations. METHODS: PET-CT allows for the correlation of two separate imaging modalities, combining both morphological and metabolic information. We should use the CT to help interpret the PET findings. In this article we will highlight specific false-negative and false-positive findings that one should be aware of when interpreting oncology scans. RESULTS: We aim to highlight post-treatment conditions that are encountered routinely on restaging scans that can lead to false-positive interpretations. We will emphasise the importance of using the CT component to help recognise these entities to allow improved diagnostic accuracy. CONCLUSION: In light of the increased use of PET-CT, it is important that nuclear medicine physicians and radiologists be aware of these conditions and correlate the PET and CT components to avoid misdiagnosis, over staging of disease and unnecessary biopsies.

Use of cone-beam computerized tomography for evaluation of bisphosphonate-associated osteonecrosis of the jaws in an experimental rat model

BACKGROUND

Bisphosphonate-induced osteonecrosis of the jaw (BONJ) is a frequently reported complication. The aim of this study was to investigate the clinical and histopathological presentation of BONJ with the Hounsfield score and to evaluate the reliability of the score for determining necrosis in an animal model.

MATERIAL/METHODS

Eighty rats were prospectively and randomly divided into two groups of 40 each: a control group and an experimental group. Half of the animals from each group underwent extraction of the left mandibular molars, and the other half underwent extraction of the left maxillary molars under pentobarbital-induced general anesthesia. All animals were euthanized 28 days after tooth extraction. Maxillae and mandibles were extracted, cone beam computed tomography (CBCT) was performed, and Hounsfield scores were evaluated.

RESULTS

The Hounsfield scores of the experimental group were found to be compatible with chronic osteomyelitis and periosteal reactions. The Hounsfield scores of the control group were compatible with a healthy healing period.

CONCLUSION

In light of these results, both cone beam computed tomography (CBCT) and the Hounsfield Units (HU) evaluations together are thought to be efficient in the diagnosis of BONJ.

Osteonecrosis of the jaw and the role of macrophages

Nitrogen-containing bisphosphonates have been associated with the development of osteonecrosis of the jaws (ONJ), but the lack of reliable epidemiological data and appropriate animal models has restricted our understanding of ONJ pathophysiology and limited its management. The best available information is from histopathologic findings, which implicate bone necrosis and infection, although it is not clear which is primary. However, there are data suggesting that macrophages could well be the central factor in allowing the infection to develop first, followed by local necrosis, which could also account for the development of ONJ in patients treated with denosumab, a human monoclonal antibody to the receptor activator of nuclear factor-κB ligand. This review examines the evidence that macrophages could play a prominent role in development of ONJ and the proposal that it may be more appropriate to view ONJ as a drug and not only a bisphosphonate-related complication.

Osteonecrosis Mimicking Bone Metastasis in Femoral Head on (18)F-FDG PET/CT: A Case Report

A 77-year-old woman underwent chemotherapy, radiotherapy, and brachytherapy for cervical cancer 9 years ago. On a follow-up (18)F-fluorodeoxyglucose (FDG) PET/CT image, focal FDG uptake was noted in a focal osteolytic lesion in the right femoral head. During magnetic resonance imaging, this lesion showed subchondral dark-signal-intensity rim on T1-weighted image and double line sign on T2-weighted image, suggestive of osteonecrosis. The lesion was pathologically confirmed as osteonecrosis after surgery. This case demonstrates that osteonecrosis of the femoral head may demonstrate focal FDG uptake mimicking bone metastasis.

International myeloma working group consensus statement and guidelines regarding the current role of imaging techniques in the diagnosis and monitoring of multiple Myeloma

Several imaging technologies are used for the diagnosis and management of patients with multiple myeloma (MM). Conventional radiography, computed tomography (CT), magnetic resonance imaging (MRI) and nuclear medicine imaging are all used in an attempt to better clarify the extent of bone disease and soft tissue disease in MM. This review summarizes all available data in the literature and provides recommendations for the use of each of the technologies. Conventional radiography still remains the 'gold standard' of the staging procedure of newly diagnosed and relapsed myeloma patients. MRI gives information complementary to skeletal survey and is recommended in MM patients with normal conventional radiography and in all patients with an apparently solitary plasmacytoma of bone. Urgent MRI or CT (if MRI is not available) is the diagnostic procedure of choice to assess suspected cord compression. Bone scintigraphy has no place in the routine staging of myeloma, whereas sequential dual-energy X-ray absorptiometry scans are not recommended. Positron emission tomography/CT or MIBI imaging are also not recommended for routine use in the management of myeloma patients, although both techniques may be useful in selected cases that warrant clarification of previous imaging findings, but such an approach should ideally be made within the context of a clinical trial.

Oral bisphosphonates as a cause of bisphosphonate-related osteonecrosis of the jaws: clinical findings, assessment of risks, and preventive strategies

PURPOSE

Oral bisphosphonates are known to have potentially profound effects on oral health. A review of the evidence supporting answers to key clinical questions is necessary to assist surgeons in the care of their patients who are receiving oral bisphosphonates.

MATERIALS AND METHODS

The literature is reviewed to address several questions, ie, what is the risk of bisphosphonate-related osteonecrosis of the jaws (BRONJ) in my patient on oral bisphosphonates? Why are so few cases of BRONJ attributable to oral bisphosphonate use? What is the importance of cofactors in the development of osteonecrosis? How major a clinical problem is BRONJ, typically, in the oral bisphosphonate patient? What dental procedures are associated with a risk of BRONJ? Are other findings apart from BRONJ of importance in the oral bisphosphonate patient? Are there proven strategies to prevent BRONJ in the oral bisphosphonate patient? Should my patient discontinue the use of oral bisphosphonates temporarily or permanently?

RESULTS

A review of the evidence offers information that will help in clinical decision-making. In general, the risk of BRONJ is between 1 in 10,000 and 1 in 100,000, but may increase to 1 in 300 after dental extraction. The great majority of BRONJ cases will likely remain in the intravenous population. Cofactors have not been firmly established, although smoking, steroid use, anemia, hypoxemia, diabetes, infection, and immune deficiency may be important. Rarely does BRONJ in the oral bisphosphonate patient appear to progress beyond stage 2, and many cases reverse with discontinuation of oral medication. Extraction is the only dental procedure shown to increase the risk of BRONJ. Dental implant therapy should be used with caution in the oral bisphosphonate patient. The benefits and risks of oral bisphosphonate use must be weighed individually and in consultation with the prescribing physician, before determining the need for temporary or permanent cessation of medication.

CONCLUSION

Emerging evidence supports clinical decisions in favor of the oral and maxillofacial surgery patient taking oral bisphosphonates.

Biophosphonate-related osteonecrosis of the jaws

In 2003 and 2004, the first reports of patients who developed necrosis of the jawbones while taking biophosphonates appeared in literature; most patients were on this drug for treatment of cancer and some osteoporosis. Since then, more than 500 cases have been identified and the number of these cases continues to grow. This article reviews the action of bisphosphonates, the condition called bisphosphonate-associated osteonecrosis of the jaws, strategies to minimize occurrence, and treatment of this condition.

Bisphosphonate-associated osteonecrosis can hide jaw metastases

BACKGROUND

Osteonecrosis of the jaw is a well known potential complication of bisphosphonate treatment but its pathogenesis is poorly understood. The current management of patients with bisphosphonate-associated osteonecrosis (BON) is based on "expert recommendations" and there is a recognized need of better evidence. We report two cases where BON hid jaw metastases and use them to discuss some limitations of the current recommendations.

PATIENTS

Two patients undergoing long-term I.V. amino-bisphosphonate treatment for metastatic cancer presented with areas of intraorally exposed jawbone. Bisphosphonate-associated osteonecrosis was diagnosed on the basis of medical history, clinical and radiological features. They underwent surgical resection of the affected jaw due to unrelenting pain and lack of response to conservative treatments.

RESULTS

Histological examination of the surgical specimen revealed cancer cells at the margins of the site of osteonecrosis. Our patients did not undergo bone biopsy according to current recommendations, due to lack of clinical and radiological signs suggestive of jaw metastases.

CONCLUSIONS

Our findings show that: i) patients with BON may also have jaw metastases; ii) there may not be clinical or imaging hints to this fact and; iii) that a biopsy based on careful selection of the site (with inclusion of necrotic margins) may be needed to reach the correct diagnosis. Further studies should be performed on this topic because of its very important prognostic implications.

Pathophysiology, risk factors and management of bisphosphonate-associated osteonecrosis of the jaw: Is there a diverse relationship of amino- and non-aminobisphosphonates?

Reports of osteonecrosis of the jaw (ONJ) in patients receiving long-term bisphosphonate therapy have appeared in the literature since 2003. This condition involves avascular necrotic bone in the area of maxilla or mandibula and there may be a secondary infection. Most cases of ONJ have been reported in cancer patients receiving the intravenous aminobisphosphonates zoledronic acid and pamidronate monthly or q 3 week; of note these are also the two most commonly used agents of this class. Risk factors for ONJ include a history of trauma, dental surgery or dental infection and intravenous bisphosphonate administration; in addition, the extent and duration of exposure to bisphosphonates also seem to correlate with the risk. Although a direct causal relationship with bisphosphonates cannot be assumed, these agents may possibly contribute to the development of ONJ by suppression of bone remodeling in the jaw which leads to increased rates of bone mineralisation and accumulation of microfractures. Clodronate, a non-aminobisphosphonate, appears to have a different mechanism of suppressing bone remodeling compared with aminobisphosphonates, and this may explain why few cases of ONJ have been reported with clodronate despite extensive use over the past 20 years; however, the potential of clodronate to reduce the risk of ONJ while providing equivalent clinical benefit to the aminobisphosphonates needs to be substantiated in controlled clinical trials. Use of bisphosphonate therapy should be carefully planned in patients with metastatic bone disease who have risk factors for ONJ, and appropriate preventive measures taken to avoid the development of this condition.