CASE 8499 Published on 30.08.2010

Acromesomelic dysplasia; Maroteaux type

Section

Paediatric radiology

Case Type

Clinical Cases

Authors

Gokalp G, Yildirim N, Yazici Z, Eren E

Patient

9 months, female

Clinical History
Twin girls with growth retardation - first noticed when they were seven months old - were referred for assessment at the age of nine months, because of short stature and head-body disproportion.
Imaging Findings
Twin girls with growth retardation (first noticed when they were seven months old), were referred at the age of nine months to the paediatric outpatient clinic, for assessment of short stature and head-body disproportion. The clinical features had become more pronounced in more recent months. The twins were the third pregnancy of a 28-year-old woman, and had been born by Caesarean section. Each had a birth weight of 1250g. The child from the first pregnancy was now a healthy 12-year-old, however, the second child had died at the age of 2-days, due to congenital heart disease and hydocephalus.

The twins had disproportionately big heads, with frontal bossing, midfacial flattening and small noses, with depressed nasal bridges. The forearms and hands were short compared to the other extremities (Figs. 1, 2), and there was laxity of hand and wrist joints. Neuromotor development was normal. A skeletal survey series of radiographs was performed, to evaluate for a possible skeletal dysplasia.


X-ray findings (Fig. 3-8):

1. Hands: Phalanges and metacarpal bones were short and thick. Epiphyses were cone-shaped. Carpal bones were normal and appropriate to age.
2. Long tubular bones: Radius and ulna were disproportionately shorter than humerus, and radius was shorter than ulna. Lower extremities were normal.
3. Spine: Vertebral body height were decreased, and central protrusion of body anterior portion (beaking) was seen. Interpedicular distance was normal. Mild kyphosis was present at lower thoracic region.
4. Calvarium: Dolicocephaly with prominent frontal and occipital bones was seen. There was frontal bossing. Facial bones were normal.
Discussion
Skeletal dysplasias comprise a group of hereditary disorders characterised with growth and development disturbances of cartilage and bones. They can be epiphyseal, metaphyseal or diaphyseal. The disease results in abnormal, and disproportionate shape and length of affected bones. Though molecular tests are available for some of its variants, radiological and clinical findings are very important for the diagnosis [1-5].

Acromesomelic dysplasia is a rare form of skeletal dysplasia, with autosomal recessive inheritance pattern. The disease is characterised by both acro- and mesomelia. Other bone abnormalities affecting calvarium or vertebrae may also be present [6, 7].

The condition was initially described by Maroteaux et al. [4] in three children. Skeletal manifestations were widely described by Langer and Garrett in 28 cases [1]. Maroteaux, Hunter-Thompson and Grebe are the three sub-types of the disease. Diagnosis depends on clinical and radiological findings. Mental capacity and motor development are normal, and other organ systems are not affected [1].

Maroteaux type is the least severe form of condition. It occurs due to the mutation of NPR2 gene on chromosome 9 [2, 3]. Disproportionate shortness of forearm, short and large hands, disproportion of head and body, flattened face and small nose should suggest this diagnosis. Lower extremity findings such as short calves, small and broad feet may also be found [1].

Characteristic radiological findings occur within the first or second year of life: cone-shaped epiphyses of hands, shortness of radius comparing to ulna, short and broad phalanges, oval-shaped vertebrae with anterior beaking, and frontal bossing of calvarium are the radiological characteristics of the diagnosis. Hypoplasia of the base of the iliac bone, irregular ossification of superior acetabulum and superior inclination of clavicles may also accompany. Fusion of growth plate in hands, bending deformity of radius, dorsal subluxation of radial head, widening of central protrusion of vertebrae, posterior wedging and increase in severity of kyphosis may occur or become more pronounced during the following years [1, 7].


The most important feature which helps to distinguish Maroteaux sub-type from the other two, is the presence of vertebral abnormalities. Hunter-Thompson type affects the lower extremities, and large joint dislocations are frequently seen. Dwarfism and hypomelia are more severe in Grebe type. Deformation of long bones, fusion of carpal and tarsal bones, and absence of proximal and middle phalanges may also accompany. Calvarium and facial shape are normal in both of them [1-3].


The differential diagnosis includes pseudohypoparathyroidism and acrodysostosis, which have similar hand findings. Lack of dwarfism and normal vertebrae helps to make the differentiation. Pseudoachondroplasia form of spondylo-epiphyseal dysplasia may also present with similar beaking of vertebrae, whilst epiphyseal irregularity of long bones is significant and calvarium is normal. Cone shaped epiphyses may be a feature of achondroplasia, chondro-ectodermal dysplasia, tricorhinophalangeal dysplasia, acrodysostosis and cleidocranial dysplasias [8]. These entities are easily distinguished from acromesomelic dysplasia by their other clinical and radiological features.

Acromesomelic dysplasia is a rarely seen disorder, with typical radiological and clinical findings. Maroteaux type is distinguished from other sub-types by the presence of vertebral abnormalities.
Differential Diagnosis List
Acromesomelic dysplasia; Maroteaux type
Final Diagnosis
Acromesomelic dysplasia; Maroteaux type
Case information
URL: https://www.eurorad.org/case/8499
DOI: 10.1594/EURORAD/CASE.8499
ISSN: 1563-4086

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