Focal nodular marrow hyperplasia
Updates to Article Attributes
Focal nodular marrow hyperplasia is a rare, benign condition where there is a localised conversion of red/haematopoietic from yellow bone marrow. Its main relevance is of being of having a pseudotumour appearance mimicking skeletal metastases on MRI 1.
Pathology
Location
Most commonly located in the spine (~60%) but can also commonly occur in the femora, sacrum and ilium 2.
Radiographic features
Plain radiograph
Focal nodular marrow hyperplasia is occult 3.
CT
CT can demonstrate mild medullary sclerosis but can often appear normal 2,3.
MRI
Focal nodular marrow hyperplasia appears as an ill-defined, solitary or multifocal round-to-oval lesion without marrow oedema. The average size is ~20 mm (range 8-55 mm) 1,2.
Signal characteristics
- T1: iso to mild high signal to skeletal muscle; low signal to marrow
- T2: low signal compared to skeletal muscle and marrow
- STIR: variable including isointense to yellow marrow
- T1C+: no enhancement 1-3
Quantitative chemical shift imaging (e.g. Dixon method) demonstrate signal intensity drop of >20% between in-phase and out-of-phase imaging is shown in most (~90%) cases 2.
Nuclear medicine
Bone scintigraphy
Normal uptake is demonstrated 2.
PET-CT
Focal nodular marrow hyperplasia demonstrates mild increased uptake 2.
Differential diagnosis
- skeletal metastases: T2 signal tenders to be higher, no signal drop on chemical shift imaging 2
-<p><strong>Focal nodular marrow hyperplasia</strong> is a rare, benign condition where there is a localised conversion of red/haematopoietic from yellow <a href="/articles/bone-marrow">bone marrow</a>. Its main relevance is of being of having a pseudotumour appearance mimicking <a href="/articles/bone-metastases-1">skeletal metastases</a> on MRI <sup>1</sup>.</p><h4>Pathology</h4><h5>Location</h5><p>Most commonly located in the <a href="/articles/spinal-anatomy-1">spine</a> (~60%) but can also commonly occur in the <a href="/articles/femur">femora</a>, <a href="/articles/sacrum">sacrum</a> and <a href="/articles/ilium">ilium</a> <sup>2</sup>.</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Focal nodular marrow hyperplasia is occult <sup>3</sup>.</p><h5>CT</h5><p>CT can demonstrate mild medullary sclerosis but can often appear normal <sup>2,3</sup>.</p><h5>MRI</h5><p>Focal nodular marrow hyperplasia appears as an ill-defined, solitary or multifocal round-to-oval lesion without marrow oedema. The average size is ~20 mm (range 8-55 mm) <sup>1,2</sup>. </p><h6>Signal characteristics</h6><ul>- +<p><strong>Focal nodular marrow hyperplasia</strong> is a rare, benign condition where there is a localised conversion of red/haematopoietic from yellow <a href="/articles/bone-marrow">bone marrow</a>. Its main relevance is of being of having a pseudotumour appearance mimicking <a href="/articles/bone-metastases-1">skeletal metastases</a> on MRI <sup>1</sup>.</p><h4>Pathology</h4><h5>Location</h5><p>Most commonly located in the <a href="/articles/spinal-anatomy-1">spine</a> (~60%) but can also commonly occur in the <a href="/articles/femur">femora</a>, <a href="/articles/sacrum">sacrum</a> and <a href="/articles/ilium">ilium</a> <sup>2</sup>.</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Focal nodular marrow hyperplasia is occult <sup>3</sup>.</p><h5>CT</h5><p>CT can demonstrate mild medullary sclerosis but can often appear normal <sup>2,3</sup>.</p><h5>MRI</h5><p>Focal nodular marrow hyperplasia appears as an ill-defined, solitary or multifocal round-to-oval lesion without marrow oedema. The average size is ~20 mm (range 8-55 mm) <sup>1,2</sup>. </p><h6>Signal characteristics</h6><ul>
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