Focal nodular marrow hyperplasia
Disclosures
- updated 16 Jan 2023:
- Integral Diagnostics, Shareholder (ongoing)
- Micro-X Ltd, Shareholder (ongoing)
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Focal nodular marrow hyperplasia is is a rare, benign condition where there is a localised conversion of red/haematopoietic from yellow/fatty bone marrow. Its main relevance is 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
Focal nodular marrow hyperplasia can have 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;
lowlow signal to marrow - T2: low signal compared to skeletal muscle and marrow
- T2FS/STIR: variable including isointense to yellow marrow
- T1C+: no enhancement 1-3
Signal intensity drop of >20% between in-phase and out-of-phase quantitative chemical shift imaging (e.g. Dixon method) is shown in most (~90%) cases 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 tends to be higher, <20% 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/fatty <a href="/articles/bone-marrow">bone marrow</a>. Its main relevance is 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>Focal nodular marrow hyperplasia can have 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/fatty <a href="/articles/bone-marrow">bone marrow</a>. Its main relevance is 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>Focal nodular marrow hyperplasia can have 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>
-<strong>T1</strong>: iso to mild high signal to skeletal muscle; low signal to marrow</li>- +<strong>T1</strong>: iso to mild high signal to skeletal muscle; low signal to marrow</li>
-</ul><p>Signal intensity drop of >20% between in-phase and out-of-phase quantitative <a href="/articles/chemical-shift">chemical shift</a> imaging (e.g. <a href="/articles/dixon-method">Dixon method</a>) is shown in most (~90%) cases <sup>2</sup>.</p><h4>Nuclear medicine</h4><h5>Bone scintigraphy</h5><p>Normal uptake is demonstrated <sup>2</sup>. </p><h5>PET-CT</h5><p>Focal nodular marrow hyperplasia demonstrates mild increased uptake <sup>2</sup>. </p><h4>Differential diagnosis</h4><ul><li>- +</ul><p>Signal intensity drop of >20% between in-phase and out-of-phase quantitative <a href="/articles/chemical-shift">chemical shift</a> imaging (e.g. <a href="/articles/dixon-method">Dixon method</a>) is shown in most (~90%) cases <sup>2</sup>.</p><h4>Nuclear medicine</h4><h5>Bone scintigraphy</h5><p>Normal uptake is demonstrated <sup>2</sup>. </p><h5>PET-CT</h5><p>Focal nodular marrow hyperplasia demonstrates mild increased uptake <sup>2</sup>. </p><h4>Differential diagnosis</h4><ul><li>
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Focal nodular haematopoietic marrow hyperplasia
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focal-nodular-haematopoietic-marrow-hyperplasia.
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