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| Discussion |
A five-year-old female child presented to our pediatric clinic with pain in both lower limbs since 20 days. There was no history of lower limb swelling or fever. The patient had been diagnosed as having ‘bilateral lower limb deep venous thrombosis’ on color Doppler examination done elsewhere and had already been started on heparin injections for the same.
On admission to our institution, the patient was referred for a color Doppler examination to look for recanalisation of the deep venous system and residual thrombosis so that heparin could be stopped.
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Fig. 1 |
On color Doppler examination, the entire deep venous system of both the lower limbs was patent with normal flow and respiratory phasic variations. No filling defect or evidence of recanalaised thrombus was seen in the deep venous system.
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Fig. 2 |
Fig. 3 |
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Fig. 4 |
Fig. 5 |
However on B mode, well defined hypoehoic lesions were seen extending along the shafts of long bones of both lower limbs. The lesions were peripherally limited by the periosteum. They did not reveal any internal vascularity. The overlying musculature was normal. A diagnosis of large subperiosteal hematomas involving both the femora and the tibia was made. An MRI examination was performed for confirmation.
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Fig.6 |
Fig. 7 |
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Fig. 8 |
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MRI scan revealed lesions along the shafts of both the femora and tibia. The lesions were periosteal in location and hyperintense on both T1 and T2 weighted images suggestive of large subacute subperiosteal hematomas. No soft tissue abnormality was seen. A possibility of scurvy was suggested. Radiographs of both the lower limbs were performed.
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Fig. 9 |
Fig. 10 |
These radiographs reveal severe osteopenia with non prominence of the trabecular pattern of the long bones with pencil thinning of the cortices. White line of Frenkel as well as Trummerfield’s zones of rarefaction are also seen.
Diagnosis: A final diagnosis of scurvy with large subperiosteal hematomas was made.
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Fig. 11 |
Scurvy is a disease caused due to deficiency of vitamin C(ascorbic acid) characterized by bone disease in growing children and haemorrhagic and healing defects.
Etiopathogenesis: Ascorbic acid functions in a variety of biosynthetic pathways by accelerating hydroxylation and amidation reactions. The most clearly established function is activation of prolyl and lysyl hydroxylases from inactive precursors providing for hydroxylation of procollagen. Inadequately hydroxylated precursors cannot acquire a stable helical configuration and cannot be adequately cross linked so that they are poorly secreted from the fibroblast. Those that are secreted lack tensile strength, are more soluble and are more vulnerable to enzymatic degradation. Collagen, which normally has the highest content of hydroxyproline is the most affected protein, particularly in the blood vessels. Proline hydroxylase is also required for the formation of osteocalcin.
Skeletal changes are seen in infants and children. The primary disturbance is in the formation of osteoid matrix rather than in mineralization or calcification as occurs in rickets. In scurvy, the palisade of cartilage cells is formed as usual and is provisionally calcified. However there is insufficient production of osteoid matrix by osteoblasts. Resorption of the cartilaginous matrix then fails or slows; as a consequence there is cartilaginous overgrowth, with long spicules and plates projecting into the metaphyseal region of marrow cavity and sometimes widening of the epiphysis. The scorbutic bone yields to the stresses of weight bearing and muscle tension with bowing of the long bones of the lower legs and abnormal depression of the sternum with outward projection of the ends of the ribs.
Clinical Features: Scurvy may occur at any age but is rare in the newborn infant. Majority of cases occur in infants 6-24 months of age. Clinical manifestations require time to develop; after a variable period of vitamin C depletion, vague symptoms of irritability, tachypnoea, digestive disturbances and loss of appetite appear. There is generalized tenderness especially noticeable in the legs when the infant is picked up or when the diaper is changed. The pain results in pseudo paralysis and the legs assume the typical ‘frog position’, in which the hips and the knees are semi flexed with the feet rotated outwards. Edematous swelling along the shafts of the legs may be present. In some cases a subperiosteal hemorrhage can be palpated at the end of the femur. Changes in the gums, most noticeable when the teeth are erupted, are characterized by bluish purple spongy swellings of the mucous membrane, usually over the upper incisors. There may be a ‘rosary’ at the costochondral junctions and a depression of the sternum. Petechial haemorrhages may occur in the skin and the mucous membranes. Low grade fever is usually present. Anemia may reflect inability to utilize iron or chronic blood loss.
Radiological findings:
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Fig. 12 |
The diagnosis of scurvy is usually based on roentgenographic changes in the long bones , especially at their distal ends. Changes are greatest as a rule in the region of the knee. In the early stages, the appearance resembles that of simple atrophy of the bone. The trabaculae of the shaft cannot be discerned, and the bone assumes a ‘ground glass’ appearance. The cortex is reduced to pencil point thinness. The white line of Frenkel , which represents the zone of well calcified cartilage can be clearly discerned as an irregular but thickened white line at the metaphysis. The epiphyseal centres of ossification also have a ground-glass appearance and are surrounded by a white ring (Wimberger’s sign). At this stage scurvy cannot be diagnosed with certainty from the radiograph unless the zone of rarefaction under the white line at the metaphysic becomes apparent. The zone of rarefaction (Trummerfeld’s zone of rarefaction) is a linear break in the bone proximal and parallel to the white line. Often, it does not traverse the shaft in its entire width and may be seen only in the lateral parts as a triangular defect. A spur (Pelkan’s spur), as a lateral prolongation of the white line may be present. Epiphyseal separation may occur along the line of destruction, with linear displacement or compression of the epiphysis against the shaft. Subperiosteal hemorrhages are not visible roentgenographically in active scurvy. During healing, however the elevated periosteum becomes calcified and the affected bone assumes a dumbbell or club shape.
This case illustrates how lack of clinical awareness of the disease can result in unindicated/misdirected radiologic investigations.
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Fig. 13 |