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 Table of Contents  
CASE REPORT
Year : 2013  |  Volume : 1  |  Issue : 1  |  Page : 25-29

A case report of pyknodysostosis with cleidocranial dysplasia: Computed tomography and panoramic imaging


Department of Radio-Diagnosis, Government Medical College and Associated Group of Hospitals, Kota, Rajasthan, India

Date of Web Publication3-May-2013

Correspondence Address:
Dharmraj Meena
Department of Radio-Diagnosis, Government Medical College and Associated Group of Hospitals, Kota - 324 001, Rajasthan
India
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Source of Support: None, Conflict of Interest: None


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  Abstract 

Pyknodysostosis is an extremely rare autosomal recessive genetic osteosclerotic disorder caused by cathepsin K deficiency leading to decrease in the bone turnover. It is characterized by short stature, brachycephaly, short and stubby fingers, open cranial sutures and fontanelle, and diffuse osteosclerosis. Multiple fractures of long bones and osteomyelitis of the jaw are frequent complications. We describe a 28-year-old male with clinically as well as radiologically multislice computed tomography (CT) and panoramic studies of pyknodysostosis. The purpose of multislice CT of the jaw was to understanding of the complete abnormal facial anatomy and is useful for planning of tooth extraction and/or implantation of prosthetics as well as to know earlier changes of dental abscess and/or carries development.

Keywords: Acro-osteolysis, cleidocranial dysplasia, osteochondrodysplasia, pyknodysostosis


How to cite this article:
Meena D, Zuber M, Pawar S, Rani S. A case report of pyknodysostosis with cleidocranial dysplasia: Computed tomography and panoramic imaging. J Oral Maxillofac Radiol 2013;1:25-9

How to cite this URL:
Meena D, Zuber M, Pawar S, Rani S. A case report of pyknodysostosis with cleidocranial dysplasia: Computed tomography and panoramic imaging. J Oral Maxillofac Radiol [serial online] 2013 [cited 2019 Feb 19];1:25-9. Available from: http://www.joomr.org/text.asp?2013/1/1/25/111349


  Introduction Top


The pyknodysostosis name derives from the Greek "pyknos," meaning dense. The disorder is also known as Toulouse-Lautrec syndrome, named for the famous French artist who was thought to be afflicted with pyknodysostosis. [1]

Pyknodysostosis is an autosomal recessive disorder of osteoclast dysfunction causing osteosclerosis. Some features of pyknodysostosis overlap the common osteopetrosis and cleidocranial dysostosis. [2] It is believed that the first case description was in 1923 by Montanari; however, it was not until 1962 that Maroteaux and Lamy defined the characteristic features of pyknodysostosis. [3] Its incidence estimated to be 1.7/1 million births. [4] It is usually diagnosed at an early age, made as a result of bone fracture, because of the severe bone fragility. Oral and maxillofacial manifestations of this disease are remarkably clear. The head is usually large, frontal bossing, the nose beaked, the mandibular angle obtuse, and both maxilla and mandible hypoplastic. Dental abnormalities and impaction are observed, as well as alterations in eruption and frequent dental crowding seen. [5]

Multislice computed tomography (CT) with multiplanar reformatted 3D surface-shaded and volume-rendered images demonstrated detailed anatomic and pathologic features of the teeth and facial bones in this patient with pyknodysostosis. Excellent delineation of unerupted and partially erupted teeth was obtained. [6]


  Case Report Top


A 28-year-old man came to our Department of Radiodiagnosis for an orthopentogram, and CT of the face and upper thorax. The patient had presented to the oral-maxillofacial surgery clinic with the complaint of numerous unerupted teeth and pus discharge from gum. Panorex radiograph revealed multiple disorganized crowded deciduous and permanent teeth within the expanded maxillary, and mandibular alveolar processes [Figure 1]. Many of the teeth were unerupted or only partially erupted. Precise evaluation of anatomic relationships among teeth was difficult secondary to overlap. This problem was worst in the areas of teeth crowding. Lucencies around the unerupted teeth, possibly representing normal follicles, were present; however, ill-defined borders may have indicated a superimposed inflammatory/infectious process. The gonial angle of the mandible was obtuse.
Figure 1: Panorex radiograph revealed multiple disorganized crowded deciduous and permanent teeth within the expanded maxillary and mandibular alveolar processes

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Noncontrast CT of the maxillofacial and upper thoracic regions was performed on a multislice CT scanner (Somatom Sens 40, Siemens Medical Systems). Axial images were obtained by using 1.5-mm collimation, and multiplanar and 3D reconstructions were generated on a workstation (Syngo CT 2007S). The reconstructed maxillofacial and upper thoracic regions soft tissue inspace image revealed characteristic short stature, frontal bossing, and depressed nasal bridge and hypoplastic midface abnormalities [Figure 2]. The inspace bony reconstructed images were demonstrated clavicular and craniofacial dysplasia and dorsal kyphoscoliosis [Figure 3]a, b, Axial [Figure 4]a and sagittal [Figure 4]b reformatted images demonstrated multiple dental abnormalities. There was persistence of the deciduous teeth within the maxilla, causing marked crowding. The teeth were misaligned and disorganized, and multiple teeth were unerupted or only minimally erupted. Unerupted teeth were surrounded by well-defined lucent areas, consistent with normal follicles. Poorly marginated lucencies in this location suggested inflammation and/or infection. Along with the dental abnormalities, marked hypoplasia of the maxillary and sphenoid sinuses with undeveloped frontal sinuses was noted. Unerupted maxillary teeth were seen in the floor of the hypoplastic maxillary sinus, with a few teeth protruding into the antrum. The hard palate was relatively deep and grooved. At the level of base of skull axial [Figure 5]a and sagittal [Figure 5]b reformatted image shown thickened and sclerotic bones, nonpneumatization of temporal and mastoid air cells, hypoplastic sphenoid sinuses and undeveloped frontal sinuses. Axial images [Figure 6]a, b of skull bones revealed open fontanelles, and sutures along with wormian bones in the lambdoidal region. Wormian bones within the lambdoid suture, a finding often associated with pyknodysostosis
Figure 2: The surface-rendered 3D soft tissue reconstructed (inspace) image of maxillofacial and upper thoracic regions revealed characteristic short stature, frontal bossing, depressed nasal bridge and hypoplastic midface abnormalities

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Figure 3: (a) The surface-rendered 3D bony reconstructed (inspace) anterior posterior (AP) image was demonstrated clavicular-craniofacial dysplasia and dorsal kyposcolisis (b) The surface-rendered 3D bony reconstructed (inspace) posterior anterior (PA) image was demonstrated clavicular-craniofacial dysplasia
and dorsal kyposcolisis


Click here to view
Figure 4: (a) The axial reformatted image demonstrated numerous unerupted, misaligned and disorganized deciduous teeth within the maxilla, causing marked crowding; (b) The sagittal reformatted image demonstrated numerous unerupted, misaligned and disorganized deciduous teeth within the maxilla, causing
marked crowding


Click here to view
Figure 5: (a) The axial reformatted image shown thickened and sclerotic bones, nonpneumatization of temporal and mastoid air cells and hypoplastic sphenoid sinuses; (b)The sagittal reformatted image shown thickened and sclerotic bones, hypoplastic sphenoid sinuses and undeveloped frontal sinuses

Click here to view
{Figure 6}

The surface-rendered 3D image gave an overview of these deformities. Irregular dentition was best delineated with volume-rendered display. Interactive review at the workstation with rotation in any axis bony to soft tissue and simultaneous orthogonal/oblique multiplanar reconstructions allowed a thorough understanding of all the abnormalities.


  Discussion Top


Pyknodysostosis is a rare hereditary disorder first described by Maroteaux and Lamy (1962). The syndrome was characterized by osteosclerosis of the skeleton, short stature, and bone fragility. Facial dysmorphology, hypoplasia of the mandible, dysplasia of the skull, bones with delayed closure of the cranial sutures, clavicular dysplasia, acroosteolysis or partial aplasia of the terminal phalanges, and abnormal tooth eruption have also been reported. The pyknodysostosis is uncommonly associated with craniosynosotosis. An autosomal recessive mode of inheritance has been also suggested, and the locus of the disease was initially mapped to human chromosome 1q21 by genetic linkage. [7]

Cranial and maxillofacial features of pyknodysostosis include frontoparietal bossing, thick calvaria, open fontanelles and sutures, hypoplastic paranasal sinuses, wormian bones in the lambdoidal region, beaked nose, and an obtuse mandibular gonial angle, often with relative prognathism. [3],[8],[9]

Patients may present with frequent fractures, recurrent dental abscesses, or obstructive sleep apnea. Parental consanguinity is recognized as a cause of this autosomal-recessive disorder, the responsible gene being located on chromosome 1q21. This gene encodes cathepsin K, a cysteine proteinase that is expressed in normal osteoclasts and is mutated in patients with pyknodysostosis. [10],[11]

Intraoral features include persistence of deciduous teeth, with premature or delayed rupture of permanent teeth, which can cause crowding. Teeth was misalignment with enamel hypoplasia, and a grooved palate. [3],[8] Dental abnormalities was the most impressive finding in this patient, with persistence of deciduous teeth and delayed rupture of permanent teeth. As mentioned previously, the follicles of these unerupted teeth may become infected, leading to abscess formation. [6]

Some features of pyknodysostosis overlap the common osteopetrosis and cleidocranial dysostosis. [2] In cleidocranial dysostosis open fontanels and cranial sutures are also observed at an advanced age, although in this case, the clavicle is also involved, a bone rarely affected in pyknodysostosis. Cleidocranial dysostosis is transmitted by autosomal dominant inheritance, whereas pyknodysostosis is autosomally recessive. [12] Bone fragility and a history of frequent fractures may suggest the possibility of diagnosing osteogenesis imperfecta, although the fractures are much more severe with other associated features like choanal atresia and blue sclera. [4]

CT findings are important in patients with cranio-maxillofacial abnormalities of pyknodysostosis. Which are including hypoplastic sinuses, poor dentition, and thickening of the calvaria have been described for osteopetrosis a similar but more common entity. [13]

Compared with panorex radiographs, CT with reconstructions demonstrates greater anatomic detail. Axial imaging defines exact relationships between the unerupted teeth, which is not possible on Panorex alone. Coronal and sagittal reformatting facilitates interpretation of anatomic relationships in the craniocaudal direction. Surface rendering gives an overall perspective of the underlying bony abnormalities, and volume rendering aids in determining the 3D relationships among the abnormal teeth by making the alveolar process less conspicuous. Demonstrating the exact relationships among abnormal teeth can aid the surgeon in planning extractions and/or reconstructions. Also, improved visualization of cortical bone can aid in distinguishing infected follicles and dental abscesses from the normal well-corticated follicles of unerupted teeth. This helps the surgeon gain a complete understanding of the abnormal anatomy and is useful for planning of tooth extraction and/or implantation of prosthetics. Magnetic resonance imaging findings in patients with pyknodysostosis reveal normal cortical thickness in the calvaria; however, there is increased trabecular bone within the medullary cavity, which causes decreased marrow signal intensity. [14]

Now latest multislice CT scan software reformatted and reconstructed 3D surface-shaded, volume-rendered and inspace images demonstrated detailed anatomic and pathologic features of the teeth and facial bones in this patient with pyknodysostosis. Very excellent delineation of unerupted and partially erupted teeth was obtained.


  Conclusion Top


Although few cases of pyknodysostosis of cranio-maxillofacial abnormalities were described in CT scan modality, but presented case we were described in multislice CT with reconstructed 3D surface-shaded, volume-rendered and inspace images. We also described clinically as well as panoramic studies of pyknodysostosis. The purpose of multislice CT was to understand the complete abnormal cranio-maxillofacial anatomy and was useful to plan tooth extraction and/or implantation of prosthetics as well as to know earlier changes of dental abscess and/or carries development. Here, we also highlighted overlap features of cleidocranial dysostosis, and dorsal kyposcolisis.

 
  References Top

1.Helms CA. Metabolic bone disease. In: Brant WE, Helms CA, editors. Fundamentals of Diagnostic Radiology. Philadelphia: Lippincott Williams & Wilkins; 1999. p. 1049-59.  Back to cited text no. 1
    
2.Beighton P, Horan F, Hamersma H. A review of the osteopetroses. Postgrad Med J 1977;53:507-16.  Back to cited text no. 2
    
3.Bathi RJ, Masur VN. Pyknodysostosis A report of two cases with a brief review of the literature. Int J Oral Maxillofac Surg 2000;29:439-42.  Back to cited text no. 3
    
4.Mujawar Q, Naganoor R, Patil H, Thobbi AN, Ukkali S, Malagi N.Pycnodysostosis with unusual findings: A case report. Cases J 2009;2:6544.  Back to cited text no. 4
    
5.Alves Pereira D, Berini Aytés L, Gay Escoda C. Pycnodysostosis. A report of 3 clinical cases. Med Oral Patol Oral Cir Bucal 2008;13:E633-5.  Back to cited text no. 5
    
6.Fleming KW, Barest G, Sakai O. Dental and facial bone abnormalities in pyknodysostosis: CT findings. AJNR Am J Neuroradiol 2007;28:132-4.  Back to cited text no. 6
    
7.Caracas HP, Figueiredo PS, Mestrinho HD, Acevedo AC, Leite AF. Pycnodysostosis with craniosynostosis: Case report of the craniofacial and oral features. Clin Dysmorphol 2012;21:19-21.  Back to cited text no. 7
    
8.Hunt NP, Cunningham SJ, Adnan N, Harris M. The dental, craniofacial, and biochemical features of pyknodysostosis: A report of three new cases. J Oral Maxillofac Surg 1998;56:497-504.  Back to cited text no. 8
    
9.Glass RB, Fernbach SK, Norton KI, Choi PS, Naidich TP. The infant skull: A vault of information. Radiographics 2004;24:507-22.  Back to cited text no. 9
    
10.Krane SM, Schiller AL. Hyperostosis, fibrous dysplasia, and other dysplasias of bone and cartilage. In: Fauci AS, Braunwald E, Isselbacher KJ, Wilson JD, Martin JB, Kasper DL, editors. Harrison's Principles of Internal Medicine. New York: McGraw-Hill; 1998. p. 2269-75.  Back to cited text no. 10
    
11.Gelb BD, Shi GP, Chapman HA, Desnick RJ. Pycnodysostosis, a lysosomal disease caused by cathepsin K deficiency. Science 1996;273:1236-8.  Back to cited text no. 11
    
12.Fratzl-Zelman N, Valenta A, Roschger P, Nader A, Gelb BD, Fratzl P, et al. Decreased bone turnover and deterioration of bone structure in two cases of pycnodysostosis. J Clin Endocrinol Metab 2004;89:1538-47.  Back to cited text no. 12
    
13.Elster AD, Theros EG, Key LL, Chen MY. Cranial imaging in autosomal recessive osteopetrosis. Part I. Facial bones and calvarium. Radiology 1992;183:129-35.  Back to cited text no. 13
    
14.Karkabi S, Reis ND, Linn S, Edelson G, Tzehoval E, Zakut V, et al. Pyknodysostosis: Imaging and laboratory observations. Calcif Tissue Int 1993;53:170-3.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 5]



 

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