1. Which best describes the location of the most significant abnormality:
a. Patella
b. Femur
c. Tibia
d. Soft tissue
There is mild marrow edema within the tibial epiphysis in the region of the lateral eminence. However, the most significant finding is the oval lesion in the medial proximal metaphysis of the tibia. A large baker cyst is also noted as well as a tear at the anterior horn and body of the lateral meniscus.
2. Which descriptor does not apply to the tibial lesion?
a. Geographic
b. Expansile
c. Periostitis
d. Fracture
e. Soft tissue mass
f. More than 1 of the above
The oval lesion within the tibia is oval and well demarcated, or geographic. The cortex is thinned and mildly expanded along the medial edge but remains intact with no evidence of a fracture. No soft tissue mass is noted. While there may be a thin layer of subperiosteal fluid along the anteromedial surface of the lesion seen on the coronal STIR, there is no aggressive periosteal reaction.
3. What is not in the differential diagnosis of a metaphyseal lesion:
a. Fibrous dysplasia
b. Bone infarct
c. Giant cell tumor
d. Geode
e. Simple bone cyst
All can appear in a metaphyseal location with the exception of a geode. These are cyst-like fluid collections, often related to osteoarthritis and occur in the epiphysis in a subchondral location. While bone infarct would not be considered based on the appearance and location of this particular lesion, they can be metaphyseal in location.
Below are representative post contrast images of the tibial metaphyseal lesion.
a. Patella
b. Femur
c. Tibia
d. Soft tissue
There is mild marrow edema within the tibial epiphysis in the region of the lateral eminence. However, the most significant finding is the oval lesion in the medial proximal metaphysis of the tibia. A large baker cyst is also noted as well as a tear at the anterior horn and body of the lateral meniscus.
2. Which descriptor does not apply to the tibial lesion?
a. Geographic
b. Expansile
c. Periostitis
d. Fracture
e. Soft tissue mass
f. More than 1 of the above
The oval lesion within the tibia is oval and well demarcated, or geographic. The cortex is thinned and mildly expanded along the medial edge but remains intact with no evidence of a fracture. No soft tissue mass is noted. While there may be a thin layer of subperiosteal fluid along the anteromedial surface of the lesion seen on the coronal STIR, there is no aggressive periosteal reaction.
3. What is not in the differential diagnosis of a metaphyseal lesion:
a. Fibrous dysplasia
b. Bone infarct
c. Giant cell tumor
d. Geode
e. Simple bone cyst
All can appear in a metaphyseal location with the exception of a geode. These are cyst-like fluid collections, often related to osteoarthritis and occur in the epiphysis in a subchondral location. While bone infarct would not be considered based on the appearance and location of this particular lesion, they can be metaphyseal in location.
Below are representative post contrast images of the tibial metaphyseal lesion.
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Enhancement is seen along the periphery of the lesion. There are also peripheral nodular or frond-like foci of enhancement.
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!A list of possible differential diagnoses for a metaphyseal based lesion in the tibia in a 45 year old patient would include:
Diagnosis: Undetermined
This patient was unfortunately lost to follow up and no definitive diagnois is available. Unfortunately radiographs or other additional imaging was available. The MRI appearance suggests the lesion on radiography would most likely be lytic in appearance with a thin sclerotic rim, with fibrous dysplasia, simple bone cyst, or chondromyxoid fibroma as a probable diagnosis.
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- fibrous lesion (fibrous dysplasia, osteofibrous dysplasia, non healed NOF) - FD can have a wide range of appearance on MR and variable contrast enhacement patterns, NOF should resolve before 40 yoa and would be unusual at this age
- giant cell tumor (GCT) - tend to involve both the epiphysis and metaphysis concurrently
- aneurysmal bone cyst (ABC) - no fluid-fluid levels which is a MR characteristic of many ABC's
- metastasis
- plasmacytoma/myeloma
- simple bone cyst - often resolved by 45 yoa and more centrally located, though can occur and be eccentric and mildy expansile
- adamantinoma - tend to be more diaphyseal in location
- chondromyxoid fibroma and osteoblastoma - most occur under 30 yoa
- low grade chondrosarcoma
- osteoid osteoma - unlikely in this patient's presentation as they tend to be smaller in size with more sclerosis and a
Diagnosis: Undetermined
This patient was unfortunately lost to follow up and no definitive diagnois is available. Unfortunately radiographs or other additional imaging was available. The MRI appearance suggests the lesion on radiography would most likely be lytic in appearance with a thin sclerotic rim, with fibrous dysplasia, simple bone cyst, or chondromyxoid fibroma as a probable diagnosis.
Comments about this months case? Is your differential different? Share your thoughts!