Clinical features, diagnosis and treatment of Paget's disease of bone in mainland China: A systematic review

Radiological impact of oral bisphosphonate use on polyostotic Paget's disease of bone over a 2 year period

Paget's disease of bone is a disorder of osteoclasts which hampers the physiological process of bone remodeling. It is the most common metabolic orthopedic disease in the Caucasian populace; we report the diagnosis of Paget's disease of bone in a South-Asian male in his early 50s with a history of gastrointestinal symptoms, weight loss and back pain. An alkaline phosphatase level of 1104 IU/L was noted. A 3-phase bone scan showed noncontiguous heterogenous nuclear uptake. After exhaustive evaluation, the patient was diagnosed with Paget's disease of bone. Despite the disease activity being mitigated by alendronate and monitored by ALP levels within normal range per protocol, the patient had compression fractures of the vertebrae requiring early reinitiation of oral bisphosphonates. This raised doubts about the efficacy of metabolic marker-based management in Paget's disease of bone.

Update on the pathogenesis and genetics of Paget’s disease of bone

Studies over the past two decades have led to major advances in the pathogenesis of Paget’s disease of bone (PDB) and particularly on the role of genetic factors. Germline mutations of different genes have been identified, as a possible cause of this disorder, and most of the underlying pathways are implicated in the regulation of osteoclast differentiation and function, whereas other are involved in cell autophagy mechanisms. In particular, about 30 different germline mutations of the Sequestosome 1 gene (SQSTM1) have been described in a significant proportion of familial and sporadic PDB cases. The majority of SQSTM1 mutations affect the ubiquitin-binding domain of the protein and are associated to a more severe clinical expression of the disease. Also, germline mutations in the ZNF687 and PFN1 genes have been associated to severe, early onset, polyostotic PDB with increased susceptibly to neoplastic degeneration, particularly giant cell tumor. Mutations in the VCP (Valosin Containing Protein) gene cause the autosomal dominant syndrome “Inclusion Body Myopathy, PDB, Fronto-temporal Dementia,” characterized by pagetic manifestations, associated with myopathy, amyotrophic lateral sclerosis and fronto-temporal dementia. Moreover, germline mutations in the TNFRSF11A gene, which encodes for RANK, were associated with rare syndromes showing some histopathological, radiological, and clinical overlap with PDB and in two cases of early onset PDB-like disease. Likewise, genome wide association studies performed in unrelated PDB cases identified other potential predisposition genes and/or susceptibility loci. Thus, it is likely that polygenic factors are involved in the PDB pathogenesis in many individuals and that modifying genes may contribute in refining the clinical phenotype. Moreover, the contribution of somatic mutations of SQSTM1 gene and/or epigenetic mechanisms in the pathogenesis of skeletal pagetic abnormalities and eventually neoplastic degeneration, cannot be excluded. Indeed, clinical and experimental observations indicate that genetic susceptibility might not be a sufficient condition for the clinical development of PDB without the concomitant intervention of viral infection, in primis paramixoviruses, and/or other environmental factors (e.g., pesticides, heavy metals or tobacco exposure), at least in a subset of cases. This review summarizes the most important advances that have been made in the field of cellular and molecular biology PDB over the past decades.

Paget’s disease of bone: Report of 11 cases

BACKGROUND

Paget’s disease of bone (PDB) is a rare metabolic bone disease in China and is characterized by increased bone resorption and disorganized bone formation. The main clinical symptoms of PDB are focal or multiple bone pain and deformity with high disability. The disease has high missed diagnosis and misdiagnosis rates. This report summarizes the clinical manifestations, imaging and pathological features, and treatments of 11 patients with PDB at our hospital from 1993 to 2020 in order to improve the recognition and prognosis of PDB.

CASE SUMMARY

There were eight male and three female patients whose average age was 48.7 ± 11.0 years with a PDB course of 1-16 years. Nine patients had bone pain and bone deformities in different parts of the body, the majority of which involved the long bones. Laboratory examinations revealed elevated serum alkaline phosphatase (ALP) in all patients with an average of 618 ± 460 IU/L (normal range 0-130 IU/L), and serum calcium and phosphorus levels were in the normal range. Imageology showed that osteolysis was usually combined with osteosclerosis and/or bone deformities in single or multiple bones. ^99mTc-methylene diphosphonate bone scintigraphy revealed increased radionuclide uptake in the bone lesions. Six patients underwent bone tissue biopsy, and the typical pathological changes were a mosaic structure of the bone trabeculae with irregularly arranged cement lines and multinuclear osteoclasts. Ten of the 11 patients were effectively treated with bisphosphonates.

CONCLUSION

Early diagnosis of the rare disease PDB can be made through elevated ALP levels and typical presentations on bone X-ray and from bone tissue biopsy.

Paget's Disease of Bone in Patients under 40 Years: Two case reports and review of the literature

Paget’s disease of bone (PDB) is a focal disorder of accelerated skeletal remodelling that is uncommon in patients under the age of 40 years; it is more prevalent in older individuals. We report two cases of PDB diagnosed in early adulthood at the Mohamed Kassab Institute of Orthopedics, La Manouba, Tunisia. The first case was a 35-year-old male patient who presented in 2011 with a seven-month history of hip pain. The second case was a 39-year-old female patient who presented 2014 with chronic lower back pain. The PDB diagnosis was confirmed with clinical, biological and radiological investigations. Both patients were doing well on follow-up. Some previous cases have been reported in the literature, differing from the presented cases in some aspects; data of PDB features at differing ages is still insufficient. Early recognition of this clinical entity in young patients is important as early treatment can affect the progression of the disease.

Paget's Disease of Bone in Tunisia: A Study of 69 Patients

CONTEXT

Paget's disease of bone is a common bone disease with a striking variation in its incidence and characteristics in different parts of the world. It is uncommonly reported in African patients.

AIMS

Given the lack of studies describing the characteristics of patients with Paget's disease of bone in North Africa, we aimed to describe demographic, clinical, biochemical, and imaging characteristics, as well as treatment outcomes of Tunisian patients with Paget's disease of bone.

SUBJECTS AND METHODS

This bicentric and retrospective study included patients with Paget's disease of bone. Clinical, laboratory, radiological profile, and response to treatment were analyzed.

RESULTS

Sixty-nine patients were identified. The mean age was 64.9 ± 11.6 years and 52.2% were women. One patient reported a positive family history. Seven patients were asymptomatic. Bone pain was the most common presenting symptom. Eight patients had a history of malignancy. In three patients, Paget's disease of bone was diagnosed as part of a metastatic workup. Monostotic disease was found in half of the cases. The most commonly involved sites were pelvis (43.5%), femur (21.7%), and spine (21.7%). The mean serum alkaline phosphatase level at presentation was 591 U/L (68-8380). Two patients received salmon calcitonin (2.8%) and 47 patients (68.1%) received bisphosphonates. After a mean follow-up of 55 months (2-240 months), bone pain improved in 43.1% of patients and the serum alkaline phosphate levels had normalized in 22 of them (43.1%). During follow-up, there was no malignant transformation.

CONCLUSIONS

In this series of Tunisian patients, Paget's disease of bone had a female predominance and was usually monostotic. The clinical and radiological presentations were similar to the European series.