Presentation
Pain and swelling over the left knee. Not keen to walk.
Patient Data
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Diffusely abnormal coarse appearances of the medulla of both the femur and distal tibia.
Associated periosteal reaction most pronounced at the proximal tibial diaphysis.
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Images of the left femur with florid periosteal reaction.
Parosteal soft tissue, appearing layered rather like an onion.
Two enlarged lymph nodes on the medial aspect of the knee.
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MRI LOWER LIMBS AND PELVIS - MSK - WITH CONTRAST
Plain films of the left tibia and fibula reviewed. Extensive femoral and tibial periosteal reaction and coarse, altered medullary bone.
Extensive bilateral parosteal soft tissue surrounding both femurs, most pronounced in the distal metaphyseal and epiphyseal regions. This extends along more than half of the diaphysis on the left femur and measures up to 1.5cm in depth at the left distal metaphysis. This gives a laminated onion skin'' appearance of the bones (on axial images).
The cortex of the femurs remains intact, but altered enhancing bone marrow in the left femur is evident.
Similar findings are present in both tibias with parosteal soft tissue up to 7 mm in depth and altered bone marrow signal. The cortex of the left tibia is irregular and breached. The distal left tibia is similarly involved.
Two morphologically abnormal lymph nodes on the medial aspect of the left knee measuring 2.8 cm and 1.1cm. 1 cm big left inguinal lymph node.
Normal pelvis.
Increased parosteal soft tissue surrounding the left distal radial and ulnar metaphyses on the localizer images.
In summary: The appearances are most suggestive of a hematological malignancy, such as leukemia.
The differential of stage IV nephroblastoma is unlikely as an ultrasound of the abdomen and both CXR/AXR has not identified a primary.
Well defined 4.5 cm hypoechoic mass in the right lobe of the liver.
The retroperitoneum is normal.
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The histology report for the surgical biopsy, taken from the tibia.
Case Discussion
Acute lymphoblastic leukemia (ALL) accounts for 15-20% of childhood leukaemias, commonly affecting young children (2-10 years of age).
In children it preferentially involves the long bones, the femur being the most common site. A variety of appearances of bony involvement may be identified on plain radiograph, one being permeative bone involvement, with a quarter having some form of periosteal reaction, which includes lamellar and sunburst types. Extramedullary soft tissue is a feature of chloroma.
The differential diagnoses initially proposed for this case include metastatic neuroblastoma, Langerhans cell histiocytosis, lymphoma, and osteomyelitis.