Evaluation of Bone Metabolism Biomarkers in Paget's Disease of Bone

A rare case of asymptomatic Paget's disease of the skull in a 60-year-old Asian female

Background and Aim

Paget's disease of the bone refers to a chronic cumulative disorder characterized by enhanced osteoclastic function followed by a secondary surge in osteoblastic activity. The condition can manifest as a polyostotic or monostotic bone disease with most patients having an asymptomatic presentation, although some may complain of pain localized to the affected bone while others express symptoms of nerve compression. A pagetic bone is predisposed to develop pathological fractures, bony deformities, and a rare yet detrimental transformation into osteosarcoma. Detection is often accidental when performing radiographic tests for other indications or when elevated blood levels of alkaline phosphatase (ALP) are detected. Treatment with third-generation bisphosphonates is helpful in preventing further bone resorption and, additionally, reduces bony pains that are believed to be caused by excessive metabolic activity. Here, we present a case of a middle-aged asymptomatic female with elevated serum ALP levels up to 1537 IU/L (reference range 40-150 U/L) during her pre-operative evaluation for elective cholecystectomy.99m Tc-methylene diphosphonate bone scintigraphy revealed diffuse uptake in the skull and, hence, was diagnosed as a case of isolated Paget's disease of the skull.

Relevance for Patients

The rarity of this disease in Southeast-Asians, its uncontrived detection, and the isolated skull involvement, imparts high clinical relevance on this case. Early detection and management of this disease can help prevent the development of life-threatening complications in affected patients, hence decreasing the morbidity.

Serum Sclerostin and Its Association with Bone Turnover Marker in Metabolic Bone Diseases

Sclerostin is a secreted inhibitor of Wnt/β-catenin signaling that is mainly produced by osteocytes and is an important regulator of bone remodeling. Some studies have evaluated serum sclerostin levels in metabolic bone diseases, but the results have been contradictory. The profile of serum sclerostin levels in patients with osteogenesis imperfecta (OI), X-linked hypophosphatemia (XLH), and Paget's disease of bone (PDB) was obtained to determine their association with bone turnover marker. Serum sclerostin levels, biochemical parameters, and the bone turnover marker, β-CrossLaps of type 1 collagen containing cross-linked C-telopeptide (β-CTX), were measured in 278 individuals, comprising 71 patients with OI, 51 patients with XLH, 17 patients with PDB, and 139 age- and sex-matched healthy controls. A correlation analysis was performed between sclerostin and β-CTX concentration. The univariate logistic regression analysis was used to analyze factors associated with OI, XLH, and PDB. Patients with PDB (11 male 6 female), aged 44.47 ± 14.75 years; XLH (17 male, 34 female), aged 19.29 ± 15.65 years; and OI (43 male, 28 female), aged 19.57 ± 16.45 years, had higher sclerostin level than age- and sex-matched healthy controls [median(interquartile range): 291.60 (153.42, 357.35) vs. 38.00 (27.06, 68.52) pmol/L, 163.40 (125.10, 238.20) vs. 31.13 (20.37, 45.84) pmol/L, and 130.50 (96.12, 160.80) vs. 119.00 (98.89, 194.80) pmol/L, respectively; P < 0.001]. Patients with PDB had the highest level of serum sclerostin, followed by those with XLH and OI (P < 0.05). Sclerostin was positively correlated with β-CTX in OI and XLH (r = 0.541 and r = 0.661, respectively; P < 0.001). Higher β-CTX and sclerostin levels were associated with a higher risk of OI, XLH, and PBD. Sclerostin may be a biomarker of OI, XLH, and PDB. Whether sclerostin inhibitors can be used in these patients requires further analysis using additional cohorts.

Molecular Mechanisms Leading from Periodontal Disease to Cancer

Periodontitis is prevalent in half of the adult population and raises critical health concerns as it has been recently associated with an increased risk of cancer. While information about the topic remains somewhat scarce, a deeper understanding of the underlying mechanistic pathways promoting neoplasia in periodontitis patients is of fundamental importance. This manuscript presents the literature as well as a panel of tables and figures on the molecular mechanisms of Porphyromonas gingivalis and Fusobacterium nucleatum, two main oral pathogens in periodontitis pathology, involved in instigating tumorigenesis. We also present evidence for potential links between the RANKL–RANK signaling axis as well as circulating cytokines/leukocytes and carcinogenesis. Due to the nonconclusive data associating periodontitis and cancer reported in the case and cohort studies, we examine clinical trials relevant to the topic and summarize their outcome.

Long-Term Efficacy of Intensive Zoledronate Therapy and Predictors of Retreatment in Paget's Disease of Bone

Despite the current debate on the best therapeutic approach, i.e. symptomatic vs intensive strategy, one zoledronate (Zol) infusion is effective in most patients with Paget's disease of bone (PDB), whereas few need retreatment, whose predictors are not well established. We aimed to evaluate long-term efficacy of intensive Zol therapy and predictors of retreatment in PDB. Pagetic complications, clinical and biochemical response to Zol together with frequency of retreatment were retrospectively assessed in forty-seven PDB patients (age, mean ± SD: 72.5 ± 8.9 years, M/F: 24/23; symptomatic/asymptomatic: 16/31). Statistical analysis for retreatment prediction were based on Mann-Whitney U test, Pearson's Χ2 and ROC curve analysis. During seven-year follow-up, all patients achieved pain relief and only one underwent arthroplasty. Bone alkaline phosphatase (BAP) detected three non-responder (6%) and six relapsing (13%) patients needing retreatment. Retreated patients had less old age (66.1 ± 11.2 vs 74.0 ± 7.7 years), higher frequency of polyostotic disease (78% vs 40%) and higher baseline (96.5 ± 24.8 vs 44.9 ± 27.7 mcg/l) and post-Zol nadir BAP levels (24.7 ± 24.1 vs 8.1 ± 4.1 mcg/l) than patients treated once (p < 0.05 for all comparisons). In multivariate analysis both serum baseline and post-Zol nadir BAP significantly predicted retreatment (OR 1.09, 95%CI 1.01-1.17 and 1.29, 1.03-1.62, respectively), with ROC curve analysis showing the greatest accuracies for threshold values of 75.6 and 9.9 mcg/l (sensitivity 88 and 90%, specificity 94 and 86%, AUC 0.92 and 0.93, respectively). Our data in mostly asymptomatic, metabolically active PDB patients treated with intensive Zol therapy show a negligible incidence of pagetic complications and long-term optimal disease control, with BAP being the best predictor of retreatment.