A 20-year-old female patient with disproportionate short stature and mild cognitive impairment presented with progressive joint stiffness and rapid onset of fatigue. Clinical evaluation revealed coarse face, and joint contractures. Echocardiography demonstrated cardiac valve thickening and ophthalmologic examination showed mild macular pigment changes. There was an excess excretion of urinary glycosaminoglycans.
A lateral skull radiograph (Fig. 1) showed thickened diploe, and J-shaped enlargement of the sella turcica. Small acetabular roofs, and irregular femoral heads were seen on the pelvic radiograph (Fig. 2). There was a V-shaped deformity of the wrist, with irregular carpal bones (Fig. 3). Chest radiograph (Fig. 4) revealed small clavicles and there was a canoe paddle appearance of the ribs. Lumbar (Fig. 5a) and cervical (Fig. 5b) radiographs showed anteroinferior beaking, and anterior vertebral wedging. These findings were consistent with “dysostosis multiplex congenita”. Based on the clinical and imaging features of “dysostosis multiplex congenita”, and additional laboratory findings, the diagnosis of Maroteaux-Lamy syndrome was made.
Mucopolysacharidosis (MPS) type VI, or Maroteaux-Lamy syndrome is a rare autosomal recessive disease, characterised by a deficient arylsulfatase B (ASB) activity, leading to accumulation of dermatan sulfate (DS), a glycosaminoglycan (GAG) in different tissue types . Typical clinical findings include short stature, coarse face, premature degenerative joint disease, corneal clouding, progressive hearing loss, impaired pulmonary and cardiac function, and organomegaly. There is usually normal mental development. Elevated intracranial pressure can lead to optic nerve atrophy and blindness . This wide spectrum of symptoms can be slowly or rapidly progressive, with the latter form already becoming apparent in the early years of life .
Plain radiographs may reveal variable features of “dysostosis multiplex congenita”. This is characterised by a scaphocephalic skull, enlargement of the cranial bones with widening of the diploe, J-shaped or omega-shaped sella turcica, variable deformities of vertebral bodies (either wedge-shaped flattening, oval-or bullet-shaped), canoe-paddle appearance of the ribs, short clavicles with a hypoplastic lateral part, small scapulae in an elevated position, small acetabular roofs, fragmented and widened femoral heads, bowed radii and ulnae, V-shaped deformity of the wrist with irregular carpal ossification, pointing base of the metacarpals, and widening of the metacarpals and phalanges. Unfortunately, dysostosis multiplex congenita is not pathognomonic for MPS VI and be seen in other types of MPS (e.g. Hurler syndrome), mucolipidoses, and other storage diseases [1, 2]. Therefore, the final diagnosis can only be made by combining radiological and clinical findings with laboratory results showing a reduced ASB activity in leukocytes, and an elevated urinary GAG excretion [1, 3].
Treatment consists of enzyme replacement therapy. The sooner this treatment is initiated, the better the prognosis [1, 4]. Without treatment, patients with rapidly progressing disease die early in the third decade of life between the age of 20 and 30 due to cardiopulmonary failure. Patients with the slowly progressive disease die between the age of 40 and 50 . The radiologist may have a pivotal role in recognising dysostosis multiplex, suggesting an underlying lysosomal storage disease.
Differential Diagnosis List
All types of MPS
Other storage diseases like multiple sulfatase deficiency
carbohydrate-deficient glycoprotein syndrome
and GM1 gangliosidosis