Brown tumor
Updates to Article Attributes
Brown tumour, also known as osteitis fibrosa cystica or, rarely osteoclastoma, is one of the manifestations of hyperparathyroidism. It represents a reparative cellular process, rather than a neoplastic process. Histologically brown tumours are identical to giant cell tumor (both are osteoclastomas), and therefore, this entity can easily be misdiagnosed as such if elevated blood calcium and/or parathormone levels are not assessed for and identified.
Epidemiology
Brown tumours have a slightly greater frequency in primary than in secondary hyperparathyroidism (3% versus 2%). However, secondary hyperparathyroidism is much more common than primary hyperparathyroidism, therefore most of brown tumours that are seen are associated with secondary hyperparathyroidism.
Pathology
In chronic renal disease, continual and excessive urinary calcium excretion can lower serum calcium level and lead to a rise in parathyroid hormone secretion. This results in moblisationmobilisation of skeletal calcium through rapid osteoclastic turnover of bone to maintain normal serum calcium levels.
In localised regions where bone loss is particularly rapid, haemorrhage, and reparative granulation tissue, with active, vascular, proliferating fibrous tissue may replace the normal marrow contents, resulting in a brown tumour.
Haemosiderin imparts the brown colour (hence the name of the lesions).
Radiographic features
Plain radiograph
Well-defined, purely lytic lesions that provoke little reactive bone. The cortex may be thinned and expanded, but will not be penetrated.
CT
Attenuation values on CT will be in the range of blood and fibrous tissue.
MRI
The MRI appearance depends on the relative proportion of its components. The lesions, therefore, may be solid, cystic, or mixed. Solid components are intermediate to low intensity on T1- and T2-weighted images, while the cystic components are hyperintense on T2-weighted images and may have fluid-fluid levels.
- T1 C+ (Gd): there can be enhancement of the solid component and septa
Angiography
- lesions are usually hypervascular
Nuclear medicine
Bone scan often shows intense uptake.
Differential diagnosis
- mnemonic for the differential diagnosis of a benign, lytic bone lesion: FEGNOMASHIC
-<p><strong>Brown tumour</strong>, also known as <strong>osteitis fibrosa cystica </strong>or, rarely <strong>osteoclastoma</strong>, is one of the manifestations of <a href="/articles/hyperparathyroidism">hyperparathyroidism</a>. It represents a reparative cellular process, rather than a neoplastic process. Histologically brown tumours are identical to <a href="/articles/giant-cell-tumour-of-bone">giant cell tumor</a> (both are osteoclastomas), and therefore, this entity can easily be misdiagnosed as such if elevated blood calcium and/or parathormone levels are not assessed for and identified. </p><h4>Epidemiology</h4><p>Brown tumours have a slightly greater frequency in primary than in secondary hyperparathyroidism (3% versus 2%). However, secondary hyperparathyroidism is much more common than primary hyperparathyroidism, therefore most of brown tumours that are seen are associated with secondary hyperparathyroidism.</p><h4>Pathology</h4><p>In <a href="/articles/chronic-kidney-disease">chronic renal disease</a>, continual and excessive urinary calcium excretion can lower serum calcium level and lead to a rise in <a href="/articles/parathyroid-hormone">parathyroid hormone</a> secretion. This results in moblisation of skeletal calcium through rapid osteoclastic turnover of bone to maintain normal serum calcium levels.</p><p>In localised regions where bone loss is particularly rapid, haemorrhage, and reparative granulation tissue, with active, vascular, proliferating fibrous tissue may replace the normal marrow contents, resulting in a brown tumour.</p><p>Haemosiderin imparts the brown colour (hence the name of the lesions).</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Well-defined, purely lytic lesions that provoke little reactive bone. The cortex may be thinned and expanded, but will not be penetrated.</p><h5>CT</h5><p>Attenuation values on CT will be in the range of blood and fibrous tissue.</p><h5>MRI</h5><p>The MRI appearance depends on the relative proportion of its components. The lesions therefore may be solid, cystic, or mixed. Solid components are intermediate to low intensity on T1- and T2-weighted images, while the cystic components are hyperintense on T2-weighted images and may have fluid-fluid levels.</p><ul><li>- +<p><strong>Brown tumour</strong>, also known as <strong>osteitis fibrosa cystica </strong>or, rarely <strong>osteoclastoma</strong>, is one of the manifestations of <a href="/articles/hyperparathyroidism">hyperparathyroidism</a>. It represents a reparative cellular process, rather than a neoplastic process. Histologically brown tumours are identical to <a href="/articles/giant-cell-tumour-of-bone">giant cell tumor</a> (both are osteoclastomas), and therefore, this entity can easily be misdiagnosed as such if elevated blood calcium and/or parathormone levels are not assessed for and identified. </p><h4>Epidemiology</h4><p>Brown tumours have a slightly greater frequency in primary than in secondary hyperparathyroidism (3% versus 2%). However, secondary hyperparathyroidism is much more common than primary hyperparathyroidism, therefore most brown tumours that are seen are associated with secondary hyperparathyroidism.</p><h4>Pathology</h4><p>In <a href="/articles/chronic-kidney-disease">chronic renal disease</a>, continual and excessive urinary calcium excretion can lower serum calcium level and lead to a rise in <a href="/articles/parathyroid-hormone">parathyroid hormone</a> secretion. This results in mobilisation of skeletal calcium through rapid osteoclastic turnover of bone to maintain normal serum calcium levels.</p><p>In localised regions where bone loss is particularly rapid, haemorrhage, and reparative granulation tissue, with active, vascular, proliferating fibrous tissue may replace the normal marrow contents, resulting in a brown tumour.</p><p>Haemosiderin imparts the brown colour (hence the name of the lesions).</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Well-defined, purely lytic lesions that provoke little reactive bone. The cortex may be thinned and expanded, but will not be penetrated.</p><h5>CT</h5><p>Attenuation values on CT will be in the range of blood and fibrous tissue.</p><h5>MRI</h5><p>The MRI appearance depends on the relative proportion of its components. The lesions, therefore, may be solid, cystic, or mixed. Solid components are intermediate to low intensity on T1- and T2-weighted images, while the cystic components are hyperintense on T2-weighted images and may have fluid-fluid levels.</p><ul><li>