Case of the Week 105

Case of the Week 105Case of the Week 105

24 year old male presented to the practice of Daniel 24 year old male presented to the practice of Daniel Mühlemann, DC (Zürich) with an insidious onset of Mühlemann, DC (Zürich) with an insidious onset of

knee pain for the past 6 weeks. He also complained of knee pain for the past 6 weeks. He also complained of pain at night. The clinical question was pes anserine pain at night. The clinical question was pes anserine

bursitis vs. an osseous lesion. bursitis vs. an osseous lesion.

What are the abnormal findings? What is the What are the abnormal findings? What is the DDX? What should be done next?DDX? What should be done next?

AnswersAnswers Abnormal findings:Abnormal findings:

There is a multi-lobulated lytic There is a multi-lobulated lytic lesion in the proximal lesion in the proximal metaphysis of the tibia. In metaphysis of the tibia. In places it is well marginated places it is well marginated (superiorly) while in others the (superiorly) while in others the borders are not that sharp. borders are not that sharp. The cortex is intact, there is no The cortex is intact, there is no periosteal reaction and no soft periosteal reaction and no soft tissue mass.tissue mass.

DDX:DDX: Brodies abscess vs. Giant Cell Brodies abscess vs. Giant Cell

Tumour (GCT) vs. Aneurysmal Tumour (GCT) vs. Aneurysmal bone cyst (ABC) vs. low-grade bone cyst (ABC) vs. low-grade Osteosarcoma. However, a Osteosarcoma. However, a GCT typically extends into the GCT typically extends into the epiphysis to the articular epiphysis to the articular surface and an ABC is very surface and an ABC is very expansile.expansile.

What should be done next?What should be done next? Laboratory evaluation and Laboratory evaluation and

MRI.MRI.

MRI slices (and on next slide)MRI slices (and on next slide)T1 Coronal slice

T1 axial sliceContrast Enhanced fat supressed axial slice

What are the abnormal findings? What is the likely What are the abnormal findings? What is the likely Diagnosis?Diagnosis?

Contrast enhanced fat suppressed sagittal slice

T 2 weighted sagittal slices

AnswersAnswers Abnormal findings:Abnormal findings:

The multi-lobulated lesion The multi-lobulated lesion previously noted appears well previously noted appears well marginated on the MRI slices marginated on the MRI slices and is low signal intensity on and is low signal intensity on T1 with high signal on T2 T1 with high signal on T2 weighted images. weighted images.

It enhances with contrast, It enhances with contrast, particularly the border.particularly the border.

Bone marrow edema is noted Bone marrow edema is noted surrounding the lesion (low surrounding the lesion (low signal on T1 and high signal signal on T1 and high signal on the contrast enhanced fat on the contrast enhanced fat suppressed slices).suppressed slices).

Contrast enhancement of the Contrast enhancement of the soft tissues anterior and soft tissues anterior and medial to the proximal tibia is medial to the proximal tibia is noted.noted.

Likely Diagnosis:Likely Diagnosis: Brodies Abscess.Brodies Abscess.

Laboratory ResultsLaboratory Results

A CBC (complete blood count), Alkaline A CBC (complete blood count), Alkaline Phosphatase, LDH, and C-Reactive Phosphatase, LDH, and C-Reactive protein (CRP) were ordered.protein (CRP) were ordered.

The only abnormalities found were:The only abnormalities found were:CRP = 28 mg/l (normal is up to 5)CRP = 28 mg/l (normal is up to 5)ESR (sedimentation rate) = 36 mm/h (normal ESR (sedimentation rate) = 36 mm/h (normal

is up to 8)is up to 8)The WBC along with the differential were The WBC along with the differential were

within normal limits. within normal limits.

Follow UpFollow Up

The patient was referred to an The patient was referred to an Orthopaedic surgeon. Orthopaedic surgeon.

This was a proven case of Brodies This was a proven case of Brodies abscess. abscess.