Case A rare case of polycarpyly in a patient with Ellis - van Creveld syndrome: plain film findings and additional value of MRI.

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1 Case A rare case of polycarpyly in a patient with Ellis - van Creveld syndrome: plain film findings and additional value of MRI. M. Mespreuve 1, 2 F. Vanhoenacker 1, 2 F. Malfait 3 D. Mortier 4 G. Mertens 5 Section: Musculoskeletal System Published: 2015, Apr. 9 Patient: 11 year(s), male Authors' Institution (1) Department of Radiology, St.-Maarten General Hospital, Leopoldstraat 2, 2800 Mechelen, Belgium (2) Department of Radiology, University Hospital Ghent, Ghent, Belgium, (3) Center for Medical Genetics, University Hospital Ghent, Ghent, Belgium, (4) Department of Orthopedic Surgery, St.-Maarten General Hospital, Mechelen, Belgium, (5) Department of Pediatrics, St.-Maarten General Hospital, Mechelen, Belgium. marc.mespreuve@skynet.be Clinical History A posttraumatic radiography in an 11-year-old boy with known postaxial polydactyly in the context of an Ellis - van Creveld syndrome, revealed - besides the radial fracture - at the ulnar side of the distal carpal row a fifth bone and at its radial side an abnormal large carpal bone. Imaging Findings

2 A fifth distal carpal bone (FDCB) was present at the ulnar side, articulating with the V-VIsynmetacarpal. The adjacent large bone resembled at its radial side a capitate bone with a rounded head proximally articulating with the lunate bone and the long flexor tendons were running radially of the hamulus at its ulnar-palmar side, hallmarks of a ham-shaped hamato-capitate fusion bone (HCFB). The more centrally located bone articulated with the 3rd metacarpal distally, extended to the scapholunate joint and had a rounded head proximally communicating with a smaller facet at the radial side of the lunate bone. The radioscaphocapitate ligament and part of the thumb adductor muscle were attached to it, a deep groove at the radial side formed its neck and part of the thumb adductor muscle was running past it and the base of the 3rd metacarpal. This was considered as a smaller capitate bone (C). Discussion The autosomal recessive Ellis-van Creveld syndrome (EvC) is reported in 1 in births with an equal sex ratio. About 300 cases have been reported. Bilateral postaxial polydactyly is a constant finding in the hands and is present in about 10% of the feet [1, 2]. There are two types (A: well formed digit and B: rudimentary skin tag). Short limbs (mesomelic) are responsable for a disproportionate dwarfism. The short ribs cause a narrow thoracic cage with vital capacity reduction. Congenital heart defects occur in about 60%. A third of EvC die of cardiac or respiratory distress in infancy. The surviving patients have a normal life expectancy [1], psychomotor and cognitive development [3]. Previously, polydactylies were considered duplication defects. In 1/600 newborns present with an upper limb abnormality [4]. They have a high perinatal mortality rate [5]. Most congenital defects of the hand have a monogenic basis, especially when they are bilateral [2]. EvC is caused by loss-of-function mutations in the genes EVC or EVC2. Plain radiography and MRI of the hand show a constant bilateral hexadactyly [1]. Five subtypes of postaxial polydactyly are identified in type A [6]. All metacarpals are shortened and broad. The extra digit has only two phalanges. The proximal phalanx of the 6th digit is hypertrophic. The other proximal and middle phalanges are dumbbell shaped with a coned epiphyseal ossification center. The middle and distal phalanges are shorter (acromesomelia). The terminal phalanges are hypoplastic. Fusion of carpal bones is frequent, mostly of the hamate and capitate bone. The ham-shaped HCFB [3, 7] is present in about 25% [8]. All of the previous abnormalities were present in our patient. Accessory carpal bones may be seen, mostly at the ulnar side of the hamate, also known as the Fifth Distal Carpal Bone (FDCB) [7, 8]. When this FDCB, as in our case is not fused with the hamate bone, it articulates with the triquetral bone proximally, the bases of the 5 th and/or 6th metacarpals distally and the hamate bone laterally. The abnormalities of the carpal bones tend to be symmetrical [8]. A FDCB fused with HCFB may be unique for EvC [8]. MRI may moreover help to better assess the bony and associated soft tissue abnormalities. The presence and the path of the tendons and ligaments may be clearly demonstrated. Oedema of carpal bones may be present in case of malfunctioning of an aberrant bony configuration. Final Diagnosis A rare case of polycarpyly in a patient with Ellis - van Creveld syndrome.

3 Differential Diagnosis List Short limb syndrome with polydactyly, Mc Kusick Kaufmann syndrome, Asphyxiating thoracic dystrophy, Achondroplasia, Chondrodysplasia punctata, Morquio syndrome, Weyers acrodental dysostosis Figures Figure 1 Plain radiography of the right hand Postaxial polydactyly. V-VI-synmetacarpalism. Hypertrophic proximal and absent middle phalanx. Shortened and broader (white arrows) metacarpals. Dumbbell shaped phalanges (horizontal black arrows). Phalangeal acromesomelia (vertical black arrows). Hypoplastic terminal phalanges (oval). Figure 2 Plain radiography with detail of the right carpus

4 Polycarpyly: small Capitatum (C), Hamato-Capitate Fusion Bone (HC) and Fifth Distal Carpal Bone (FDCB). Figure 3 Plain radiography of the carpal bones of the right hand Hamulus (white arrow). Rounded head articulating with the lunate (small white arrow). The capitate: articulation with the 3rd metacarpal (small vertical black arrow), with a lunate facet (large black arrow). Neck groove (horizontal black arrow). (1) Department of Radiology, St.-Maarten General Hospital, Leopoldstraat 2, 2800 Mechelen, Belgium

5 Figure 4 Plain radiography of the left hand. Symmetrical findings, compared to the right side. Figure 5 MRI of the right hand. Coronal SE T1-WI The capitate bone (C), the hamato-capitate fusion bone (HC) an the fifth distal carpal bone (FDCB) are indicated.

6 Figure 6 MRI Axial SE-T1-WI (at the white line in fig. 4) The capitate bone (C), the hamato-capitate fusion bone (HC) an the fifth distal carpal bone (FDCB) are indicated. Figure 7 MRI of the right hand. Coronal SE T1-WI. Note the hamulus on the large fusion bone (white arrow) located at the ulnar side of all the long flexor tendons.

7 Figure 8 Coronal SE PD -WI of the right wrist The palmar radioscaphocapitate ligament (white arrows) helps to identify the capitate bone.no bone marrow oedema due to malfunctioning, despite of the abnormal configuration of the distal carpal row. Figure 9 Axial SE T1-WI of the right hand The attachment of the thumb adductor muscle (white arrows) is running - as normally - to the 3rd metacarpal base and capitate bone and also to the 4th metacarpal base and HC (argument in favor). Figure 10 Overview of clinical features of EvC

8 Cardinal features and additional features of EVC References [1] Da Silva EO, Janovitz D, Cavalcanti S (1980) Ellis-van Creveld syndrome: report of 15 cases in an inbred kindred J Med Genet 17: [2] Philip-Sarles N (2007) Malformations congénitales de la main et génétique Chirurgie de la main 27: [3] Muensterer O, Berdon W, Mc Manus C et al. (2013) Ellis-van Creveld syndrome: its history Pediatr Radiol 43: [4] Oberg KC, Feenstra JM, Manske PR et al. (2010) Developmental biology and classification of congenital anomalies of the hand and upper extremity J Hand Surg 35: [5] Koskimies E, Lindfors N, Gissler M et al. (2011) Congenital upper limb deformities and associated malformations in Finland: a population based study J Hand Surg 36: [6] Pritsh T, Ezaki M, Mills J et al. Type A ulnar polydactyly of the hand (2013) A classification system and clinical series J Hand Surg 38: [7] Poznanski AK, Holt JF (1971) The carpals in congenital malformation syndromes AJR 112: [8] Taylor GA, Jordan CE, Dorst SK (1994) Polycarpyly and other abnormalities of the wrist in chondroectodermal dysplasia: Ellis-van Creveld syndrome Radiology 151: Citation M. Mespreuve 1, 2

9 F. Vanhoenacker 1, 2 F. Malfait 3 D. Mortier 4 G. Mertens 5 (2015, Apr. 9) A rare case of polycarpyly in a patient with Ellis - van Creveld syndrome: plain film findings and additional value of MRI. {Online} URL: