Clinical History
A 16-year-old male presented with a difficulty in walking (gait disturbance) and a deformity of both lower limbs. On examination, the patient was found to be free of H/O pain, anaemia. A plain X-ray
investigation showed that he did not have hepatosplenomegaly.
Imaging Findings
A 16-year-old male presented with a difficulty in walking (gait disturbance) and a deformity of both lower limbs. There was no history of associated pain. On examination, it was noted that he had
neither anaemia nor organomegaly. An X-ray examination of the knee joint revealed splaying of the distal femur and the proximal tibia. Successive X-rays of the upper limbs were taken and the films
revealed metaphyseal flaring extending into the diaphysis, which suggested he had Erlenmeyer Flask deformity. Splaying of the proximal and the distal end of the long bones with a thinned out cortex
and relative constriction of the central portions of the shaft were seen. The X-ray photographs of his skull appeared to be normal.
Discussion
An Erlenmeyer flask appearance is seen in Gaucher's disease, certain anaemias, fibrous dysplasia, the Niemann–Pick disease, craniometaphyseal dysplasia, Pyle's (or metaphyseal) dysplasia, heavy
metal poisoning and osteopetrosis. Pyle's (metaphyseal) dysplasia is known to be a rare disorder that shows either recessive or dominant transmission. This disorder may manifest at any age and
usually presents with mild clinical symptoms or is at times asymptomatic. Clinical symptoms include joint pain, muscular weakness, scoliosis, genu valgum, dental malocclusion and bone fragility. It
has a characteristic radiologic appearance as described above. The skull is virtually spared although minor alterations in the skull such as prominent supra orbital ridges, obtuse angle of the jaw,
mild sclerosis of the cranial vault may be seen. The ribs and medial portions of the clavicles may also show expansion. Radiological changes in the spine varying from moderate platyspondyly to bodies
having the appearance of a biconcave lens have been reported. Important differentials include the other types of metaphyseal dysplasia such as the Jansen, Schmid and McKusick types which are
associated with a short stature, skull changes, vertebrae and rib changes and cartilage hair hypoplasia. Cartilage hair hypoplasia (CHH) is an autosomal recessive inherited disorder that results in
short limb dwarfism, sparse hair and is predominantly associated with T-cell immunodeficiency. Craniometaphyseal dysplasia is the most commonly confused condition. The basic features of both the
autosomal dominant and the recessive forms are facial deformity, cranial hyperostosis and the failure of normal modelling of tubular bones. Radiologically, progressive sclerosis of the base of the
skull and about the cranial sutures, obliteration of the paranasal sinuses and a loss of lamina dura about the teeth are seen. Remodelling defects in the long bones manifested as metaphyseal
expansion, cortical thinning and club shaped epiphyses are also seen. Gaucher's disease is characterized by hepatosplenomegaly with widespread osteopenia with a coarsened trabecular pattern. Focal
osteosclerosis, ischemic necrosis of the proximal capital femoral epiphyses, periosteal reaction and endosteal scalloping are also noted in Gaucher's disease. Fibrous dysplasia and osteopetrosis have
characteristic radiological findings. Patients with anaemia and heavy metal poisoning commonly have irregular transverse radiodense lines near the ends of the long bones, which is however not
specific. The characteristic Erlenmeyer flask deformity with no changes in the skull radiograph would narrow down the diagnosis to Pyle's dysplasia.
Differential Diagnosis List
Pyle's metaphyseal dysplasia.
Final Diagnosis
Pyle's metaphyseal dysplasia.
