Pycnodysostosis. Report of a case and review of the Japanese literature, with emphasis on oral and maxillofacial findings

Clinical and radiographic characteristics of pycnodysostosis: A systematic review

Purpose

Pycnodysostosis (PYCD), an autosomal recessive syndrome, is characterized by an imbalance in bone remodeling that produces various clinical and radiographic craniofacial manifestations. This review represents a systematic examination of these manifestations, as well as oral features associated with PYCD.

Materials and Methods

A systematic review was conducted across 8 databases from February to March 2023. The search strategy focused on studies reporting cases of PYCD that examined the clinical and radiographic craniofacial and oral characteristics associated with this syndrome.

Results

The review included 84 studies, encompassing a total of 179 cases of PYCD. More than half of the patients were female (55.3%), and the mean age was 14.7 years. Parental consanguinity was reported in 51.4% of the cases. The most common craniofacial clinical manifestation was a prominent nose, observed in 57.5% of cases. Radiographically, the most frequently reported craniofacial characteristics included the presence of an obtuse mandibular angle (84.3%) and frontal cranial bosses (82.1%). Clinical and radiographic examinations revealed oral alterations, with micrognathia present in 62.6% of patients and malocclusion in 59.2%. Among dental anomalies, tooth agenesis was the most commonly reported, affecting 15.6% of patients.

Conclusion

Understanding the clinical and radiographic craniofacial features of PYCD is crucial for dental professionals. This knowledge enables these clinicians to devise effective treatment plans and improve patient quality of life.

Surgical treatment of pycnodysostosis associated with pathological tibial fracture : Case report and review of the literature

BACKGROUND

Pycnodysostosis is a rare autosomal recessive lysosomal disorder of bone characterized by diffuse skeletal condensation with thickening of the cortex and narrowing of the medullary canal.

CASE PRESENTATION

We present the case of a 4-year-old girl diagnosed with pycnodysostosis and associated pathological tibial fracture. The tibia had an absence of medullary canal. Surgery included reduction and reaming of the canal with placement of a 5 mm diameter telescopic growing nail.

CONCLUSION

The presentation of pycnodysostosis as tibial fracture is rare and there is limited literature on its management. We showed its approach focusing mainly on the management of the absent medullary canal.

Pycnodysostosis: a case report and literature review concerning oral and maxillofacial complications and their management

OBJECTIVE

There is a lack of knowledge regarding pycnodysostosis (PYCD), which is commonly misdiagnosed as other, similar malformations. This study aims to report a patient with PYCD and conjointly present a comprehensive literature review regarding oral complications after oral surgery procedures.

STUDY DESIGN

This study aims to report a noteworthy case of a 40-year-old woman with PYCD who suffered from a midface defect after iatrogenic fracture during extraction of the upper right molars. A comprehensive electronic search was carried out in January 2020 for detection and analysis of the most commonly encountered dentoalveolar PYCD-related complications. The study was granted an exemption from the local institutional review board.

RESULTS

The electronic search yielded 35 articles reporting 41 PYCD cases with 62 various reported dentoalveolar complications. The survey reported a prevalence of osteomyelitis (n = 39) followed by pathologic fracture (n = 17), iatrogenic fracture (n = 5), and oronasal communication (n = 1).

CONCLUSIONS

This study advocates handling patients with PYCD with care through the use of extensive clinical and radiographic examinations, giving priority to any conservative treatment modalities, atraumatic surgical procedures, prophylactic antibiotic prescriptions, and a regular follow-up schedule to tackle any anticipated complications.

Three-dimensional analysis of craniofacial morphology in patients with pycnodysostosis

OBJECTIVE

To perform a 3D cephalometric analysis of the craniofacial characteristics of patients with pycnodysostosis and compare this with a matched control group.

SETTING AND SAMPLE POPULATION

This cross-sectional descriptive study assessed eight CBCTs obtained in patients with pycnodysostosis (4 males, 4 females, mean age: 31.8 years).

MATERIALS AND METHODS

Eight Danish patients with pycnodysostosis were seen at the University's Orthodontic Clinic. All CBCTs were analysed using the Mimics 21.0 software (Materialise®, Belgium) and compared with a control group (6 males, 8 females, mean age: 33.6 years).

RESULTS

Interclass correlation coefficient showed excellent intra-rater reliability (> 0.93). All measurements in the 3D cephalometric analysis revealed statistical significance (P < .05) when compared with controls. Patients with pycnodysostosis generally had significantly smaller maxilla in the transverse (P < .001), sagittal (P < .002) and vertical (P < .001) dimensions. Their mandibles were also smaller vertically (P < .001) and in length (P < .001). Gonial angle was significantly larger than controls (P < .001), while mandibular volumes were considerably smaller (P < .001).

CONCLUSION

Patients with pycnodysostosis have significantly smaller jaws in the vertical, sagittal and transverse dimensions compared with controls. Furthermore, the gonial angle was significantly larger, while the volume of the mandible was significantly smaller.

Osteomyelitis of the jaws in patients with pycnodysostosis: a systematic review

Introduction

Pycnodysostosis is a rare autosomal recessive syndrome that provides the abnormal bone metabolism that increases the susceptibility of patients to develop osteomyelitis.

Objective

This systematic review was conducted to analyze the risk factors associated with the development of complications in the jaws (fractures and osteomyelitis), as well as their clinical-pathological characteristics and therapeutic approaches in patients with pycnodysostosis.

Methods

Searches were performed in the PubMed, Web of Science, Scopus, Lilacs, and Cochrane databases. Case reports or case series that met the eligibility criteria according to the PRISMA statement were included. The full texts of 31 articles were retrieved. Twenty of these articles published between 1969 and 2018 were selected, which described 26 cases of osteomyelitis in patients with pycnodysostosis.

Results

The mean age of the patients was 37.84 years; the male-to-female was 1.36:1. The mandible was the most affected site (76.9%). Tooth extraction was the main risk factor for osteomyelitis (61.5%), followed by infection (26.8%) and mandibular fracture (23.0%). Antibiotic therapy alone or combined with some surgical procedure was the treatment used in most cases (80.7%).

Conclusion

The findings of this review showed that patients with pycnodysostosis are more likely to develop osteomyelitis of the jaws after surgical procedures, especially tooth extraction which remains the main risk factor for its establishment. In addition, prophylactic antibiotic-therapy in the pre- and postoperative periods may prevent the development of osteomyelitis in pycnodysostosis.

Pyknodysostosis: Report of a Rare Case and its Dental Management

Aim

This is a case report of a 16-year-old girl visiting MR Ambedkar Dental College and Hospital (Department of Pedodontics and Preventive Dentistry) for dental treatment.

Background

Osteopetrosis acroosteolytica or Toulouse-Lautrec syndrome or pyknodysostosis is a rare autosomal recessive bone dysplasia, characterized by osteosclerosis, and short stature. Montanari described a patient with an unusual variation of achondroplasia, which in retrospect was the first case of pyknodysostosis to be reported.¹

Case description

A 16-year-old girl reported to the Department of Pediatric and Preventive Dentistry with a chief complaint of pain in the lower left back region of the jaw since past 2 weeks.

Conclusion

Pyknodysostosis is a rare condition that is diagnosed basically on its clinical and radiographic features.

Clinical significance

It is important to recognize these features so that correct diagnosis can be made. This allows the treatment and prevention of future complications and ensures a better quality of life to the patient.

How to cite this article

Jawa A, Setty JV, Vijayshankar LV, et al. Pyknodysostosis: Report of a Rare Case and its Dental Management. Int J Clin Pediatr Dent 2020;13(2):192–195.

The Genetic Architecture of High Bone Mass

The phenotypic trait of high bone mass (HBM) is an excellent example of the nexus between common and rare disease genetics. HBM may arise from carriage of many 'high bone mineral density [BMD]'-associated alleles, and certainly the genetic architecture of individuals with HBM is enriched with high BMD variants identified through genome-wide association studies of BMD. HBM may also arise as a monogenic skeletal disorder, due to abnormalities in bone formation, bone resorption, and/or bone turnover. Individuals with monogenic disorders of HBM usually, though not invariably, have other skeletal abnormalities (such as mandible enlargement) and thus are best regarded as having a skeletal dysplasia rather than just isolated high BMD. A binary etiological division of HBM into polygenic vs. monogenic, however, would be excessively simplistic: the phenotype of individuals carrying rare variants of large effect can still be modified by their common variant polygenic background, and by the environment. HBM disorders-whether predominantly polygenic or monogenic in origin-are not only interesting clinically and genetically: they provide insights into bone processes that can be exploited therapeutically, with benefits both for individuals with these rare bone disorders and importantly for the many people affected by the commonest bone disease worldwide-i.e., osteoporosis. In this review we detail the genetic architecture of HBM; we provide a conceptual framework for considering HBM in the clinical context; and we discuss monogenic and polygenic causes of HBM with particular emphasis on anabolic causes of HBM.

Genetic study of eight Egyptian patients with pycnodysostosis: identification of novel CTSK mutations and founder effect

This is the first Egyptian study with detailed clinical and orodental evaluation of eight patients with pycnodysostosis and identification of four mutations in CTSK gene with two novel ones and a founder effect.

INTRODUCTION

Pycnodysostosis is a rare autosomal recessive skeletal dysplasia due to mutations in the CTSK gene encoding for cathepsin K, a lysosomal cysteine protease.

METHODS

We report on the clinical, orodental, radiological, and molecular findings of eight patients, from seven unrelated Egyptian families with pycnodysostosis.

RESULTS

All patients were offspring of consanguineous parents and presented with the typical clinical picture of the disorder including short stature, delayed closure of fontanels, hypoplastic premaxilla, obtuse mandibular angle, and drum stick terminal phalanges with dysplastic nails. Their radiological findings showed increased bone density, acro-osteolysis, and open cranial sutures. Mutational analysis of CTSK gene revealed four distinct homozygous missense mutations including two novel ones, c.164A>C (p. K55T) and c.433G>A (p.V145M). The c.164A>C (p. K55T) mutation was recurrent in three unrelated patients who also shared similar haplotype, suggesting a founder effect.

CONCLUSION

Our findings expand the mutational spectrum of CTSK gene and emphasize the importance of full clinical examination of all body systems including thorough orodental evaluation in patients with pycnodysostosis.

Fracture Management in Pyknodysostosis - A Rare Case Report

Introduction:

Pyknodysostosis is congenital osteosclerotic skeletal dysplasia of a rare entity. It is an autosomal recessive disease which presents with short stature and generalized osteosclerosis of skeleton as result of decreased bone turnover. Here, the authors report a case of pyknodysostosis who presented to our emergency room with a pathological fracture in the shaft of the femur for which operative intervention was carried out.

Case Report:

A 30-year-old female presented to our emergency room with a history of trivial injury to right thigh region and was diagnosed as fracture in her right femur shaft region. After a detailed clinical, radiological, and blood investigations, the patient was taken up for operative modality of intervention in the form of plate osteosynthesis. As the medullary canal was narrow and bone was osteosclerotic, the option of closed intramedullary interlocking nailing was ruled out. Hence, we proceeded with open reduction and internal fixation with plate osteosynthesis using a board dynamic compression plate. Post-operative period was uneventful. Patient underwent non-weight bearing mobilization for 2 months. At 10-week post-operative follow-up, the patient presented with pain over surgical site and radiological examination showed no signs of union. The patient underwent additional plating augmented with bone grafting using grafts harvested from iliac crest and synthetic bone graft. The patient developed deep-seated infection immediate post-operative period for which she was treated with wound debridement, and appropriate intravenous antibiotics were given 2 weeks and orally for 4 weeks. At 6-month follow-up, the patient is able to carry her day-to-day activity with complete recovery and radiological signs of union. The patient had classical clinical features suggestive of pyknodysostosis. Patient has 2 siblings of same family (one brother and sister) with similar clinical and radiological features.

Conclusion:

Recognition of these clinical and radiological signs is important to make the diagnosis of pyknodysostosis and prevent possible complications. Additional care must be taken in treating these patients.

Clinical and radiographic features of pycnodysostosis: A case report

Pycnodysostosis is a rare disorder that was first described in 1962; however, it was only in 1996 that the defective gene was discovered, which led to a better understanding of this disease. This study reports and discuss a case of pycnodysostosis. In addition, a search of articles published in PubMed-Medline was performed. The case was a 13-year-old girl who was referred to a private clinic for dental treatment. Clinical examination showed midface hypoplasia, prominent cheeks, a high nasal bridge, beaked nose, spoon-shaped fingers, frontal bossing, open fontanelles and dental alterations, findings compatible with pycnodysostosis. Patients with this disease also suffer from fractures because of bone hardness with almost no elasticity, a fact that requires special care particularly in the case of children and adolescents. The diagnosis of pycnodysostosis is made based on clinical and radiographic findings. Clinicians should be aware of this disorder to provide adequate dental treatment.

Key words:Pycnodysostosis, developmental bone disease, imaging diagnosis.

Pycnodysostosis with Special Emphasis on Dentofacial Characteristics

Pycnodysostosis is an autosomal recessive disorder that manifests as osteosclerosis of the skeleton due to the defective osteoclasts mediated bone turnover. The diagnosis of this disorder is established on the basis of its characteristic features and must be differentially diagnosed with other bone disorders. Dental surgeons should be aware of the limitations and possible adverse oral complications such as osteomyelitis of bone in these patients. This will guide them in planning realistic treatment goals. This paper reports the clinical and radiographic features of pycnodysostosis with the great emphasis on its dentofacial characteristics. The aim of this case report is to give an insight into the etiology, pathogenesis, and differential diagnosis of this disorder and to prepare the dentists and maxillofacial surgeons to overcome the challenges in treating these patients.

Management of chronic suppurative osteomyelitis in a patient with pycnodysostosis by intra-lesional antibiotic therapy

Pycnodysostosis is a rare sclerosing bone disorder characterized by short stature, brachycephaly, short/stubby fingers, open cranial sutures/fontanelle, and diffuse osteosclerosis, where multiple fractures of long bones and osteomyelitis of the jaw are common complications. We present a rare case of pycnodysostosis with chronic suppurative osteomyelitis of the mandible in a 36-year-old woman; which was nonsurgically managed by a conservative approach involving a novel protocol referred to as intra-lesional antibiotic therapy.

Upper airway surgery of obstructive sleep apnea in pycnodysostosis: case report and literature review

Pycnodysostosis is an autosomal recessive disorder due to a mutation in the cathepsin K gene, which causes a decrease of the bone turnover; a review of the literature suggests that pycnodysostosis is frequently associated with severe respiratory obstruction, which needs surgical treatment. The aim of this paper is to describe the surgical treatment of a 3½-year-old girl affected by Pycnodysostosis complicated by a severe sleep-related respiratory disorder. The surgical treatment, consisting of adenotonsillectomy and palatoplasty, resulted in a striking amelioration of respiratory parameters and increased posterior airway space, and allowed the patient to avoid tracheotomy while awaiting for maxillo-mandibular surgery.

Challenges in the orthodontic treatment of a patient with pycnodysostosis

Pycnodysostosis is a rare, autosomal recessive syndrome characterized by osteosclerosis, brittle bones, stunting, and significant craniofacial changes. The objective of this study was to report a case of a 6-year-old patient with pycnodysostosis orthodontically treated and followed up until age 10 years and to discuss the risk factors, options for orthodontic treatment, and limitations involving this type of treatment, which has not yet been performed. Prevention through counseling and periodic follow-up visits is essential in eliminating factors that predispose patients to infections and fractures. New studies are necessary to establish safe and efficient orthodontic treatment plans.

Friend or foe: high bone mineral density on routine bone density scanning, a review of causes and management

A finding of high BMD on routine DXA scanning is not infrequent and most commonly reflects degenerative disease. However, BMD increases may also arise secondary to a range of underlying disorders affecting the skeleton. Although low BMD increases fracture risk, the converse may not hold for high BMD, since elevated BMD may occur in conditions where fracture risk is increased, unaffected or reduced. Here we outline a classification for the causes of raised BMD, based on identification of focal or generalized BMD changes, and discuss an approach to guide appropriate investigation by clinicians after careful interpretation of DXA scan findings within the context of the clinical history. We will also review the mild skeletal dysplasia associated with the currently unexplained high bone mass phenotype and discuss recent advances in osteoporosis therapies arising from improved understanding of rare inherited high BMD disorders.

Osteopetrosis

Osteopetrosis ("marble bone disease") is a descriptive term that refers to a group of rare, heritable disorders of the skeleton characterized by increased bone density on radiographs. The overall incidence of these conditions is difficult to estimate but autosomal recessive osteopetrosis (ARO) has an incidence of 1 in 250,000 births, and autosomal dominant osteopetrosis (ADO) has an incidence of 1 in 20,000 births. Osteopetrotic conditions vary greatly in their presentation and severity, ranging from neonatal onset with life-threatening complications such as bone marrow failure (e.g. classic or "malignant" ARO), to the incidental finding of osteopetrosis on radiographs (e.g. osteopoikilosis). Classic ARO is characterised by fractures, short stature, compressive neuropathies, hypocalcaemia with attendant tetanic seizures, and life-threatening pancytopaenia. The presence of primary neurodegeneration, mental retardation, skin and immune system involvement, or renal tubular acidosis may point to rarer osteopetrosis variants, whereas onset of primarily skeletal manifestations such as fractures and osteomyelitis in late childhood or adolescence is typical of ADO. Osteopetrosis is caused by failure of osteoclast development or function and mutations in at least 10 genes have been identified as causative in humans, accounting for 70% of all cases. These conditions can be inherited as autosomal recessive, dominant or X-linked traits with the most severe forms being autosomal recessive. Diagnosis is largely based on clinical and radiographic evaluation, confirmed by gene testing where applicable, and paves the way to understanding natural history, specific treatment where available, counselling regarding recurrence risks, and prenatal diagnosis in severe forms. Treatment of osteopetrotic conditions is largely symptomatic, although haematopoietic stem cell transplantation is employed for the most severe forms associated with bone marrow failure and currently offers the best chance of longer-term survival in this group. The severe infantile forms of osteopetrosis are associated with diminished life expectancy, with most untreated children dying in the first decade as a complication of bone marrow suppression. Life expectancy in the adult onset forms is normal. It is anticipated that further understanding of the molecular pathogenesis of these conditions will reveal new targets for pharmacotherapy.

Cephalometric characteristics and dentofacial abnormalities of pycnodysostosis: report of four cases from Brazil

Pycnodysostosis (PKND) is a human autosomal recessive genetic disorder characterized mainly by osteosclerosis of the skeleton, severe bone fragility, and short stature. This syndrome usually presents very typical craniofacial deformities, such as beaked nose, micrognathia, hypoplastic midface, open mouth posture, grooved palate, anterior cross-bite, dental crowding, and over-retained deciduous teeth. Early diagnosis and intervention are of the utmost importance. Four cases from the northeast of Brazil are reported including 2 siblings. Features included maxillary retrusion, reduced facial height, open bite, and bone fracture history. Very poor oral hygiene, severe dental caries, and periodontal disease were also present.

Multiple developmental dental anomalies and hypermobility type Ehlers-Danlos syndrome

Concurrent existence of multiple developmental dental anomalies: hypodontia of permanent mandibular incisors, dentin dysplasia, transmigration, root dilaceration, ectopic eruption and delayed eruption combined with systemic abnormalities including joint hyperlaxity and skin hyperextensibility aided in diagnosis of a sporadic case of hypermobility type of Ehlers-Danlos syndrome in a Jordanian Arab male. In dental practice the presence of multiple developmental dental anomalies expressing simultaneous defects in different stages of tooth development should raise suspicion of possible of manifestation of an underlying systemic abnormality.

Pharyngeal narrowing as a common feature in pycnodysostosis—a cephalometric study

We report on pycnodysostosis presenting as severe snoring caused by pharyngeal narrowing in two siblings. Cephalograms showed pharyngeal narrowing at the level of the soft palate and the base of the tongue caused by the long soft palate and mandibular hypoplasia. From the literature review and our results, we suggest that respiratory insufficiency such as snoring or obstructed sleep apnea are common and under-appreciated symptoms of pycnodysostosis.

Mandibular osteomyelitis and fracture successfully treated with vascularised iliac bone graft in a patient with pycnodysostosis

Pycnodysostosis is a rare sclerosing bone disorder. Complications such as osteomyelitis and fracture of the jaws are not uncommon and difficult to treat. Treatment by reconstruction with a reconstruction plate and an iliac bone graft fails in most cases. We report a case of pycnodysostosis with osteomyelitis and fracture of the mandible that was successfully treated with vascularised iliac bone graft. We believe that this procedure is the best method for the treatment of this condition.