The brown tumor is a bone lesion that arises in settings of excess

osteoclast An osteoclast () is a type of bone cell that breaks down bone tissue. This function is critical in the maintenance, repair, and remodeling of bones of the vertebral skeleton. The osteoclast disassembles and digests the composite of hydrated pro ...

activity, such as

hyperparathyroidism Hyperparathyroidism is an increase in parathyroid hormone (PTH) levels in the blood. This occurs from a disorder either within the parathyroid glands (primary hyperparathyroidism) or as response to external stimuli (secondary hyperparathyroidism). ...

. They are a form of

osteitis fibrosa cystica Osteitis fibrosa cystica ( ) is a skeletal disorder resulting in a loss of bone mass, a weakening of the bones as their calcified supporting structures are replaced with fibrous tissue ( peritrabecular fibrosis), and the formation of cyst-like br ...

. It is not a

neoplasm A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

, but rather simply a mass. It most commonly affects the maxilla and mandible, though any bone may be affected. Brown tumours are

radiolucent Radiodensity (or radiopacity) is opacity to the radio wave and X-ray portion of the electromagnetic spectrum: that is, the relative inability of those kinds of electromagnetic radiation to pass through a particular material. Radiolucency or hypod ...

on x-ray.

Pathology

Brown tumours consist of

fibrous tissue Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...

, woven bone and supporting

vasculature The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

, but no

matrix Matrix most commonly refers to: * ''The Matrix'' (franchise), an American media franchise ** ''The Matrix'', a 1999 science-fiction action film ** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...

. The osteoclasts consume the

trabecular bone A trabecula (plural trabeculae, from Latin for "small beam") is a small, often microscopic, tissue element in the form of a small beam, strut or rod that supports or anchors a framework of parts within a body or organ. A trabecula generally has ...

that

osteoblasts Osteoblasts (from the Greek combining forms for "bone", ὀστέο-, ''osteo-'' and βλαστάνω, ''blastanō'' "germinate") are cells with a single nucleus that synthesize bone. However, in the process of bone formation, osteoblasts function ...

lay down and this front of reparative bone deposition followed by additional resorption can expand beyond the usual shape of the bone, involving the

periosteum The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones. Structu ...

thus causing bone pain. The characteristic brown coloration results from

hemosiderin Hemosiderin image of a kidney viewed under a microscope. The brown areas represent hemosiderin Hemosiderin or haemosiderin is an iron-storage complex that is composed of partially digested ferritin and lysosomes. The breakdown of heme gives rise ...

deposition into the osteolytic cysts. Hemosiderin deposition is not a distinctive feature of brown tumors; it may also be seen in giant cell tumors of the bone. Brown tumors may be rarely associated with ectopic parathyroid adenomas or end stage

renal osteodystrophy Renal osteodystrophy/adynamic bone disease is currently defined as an alteration of bone morphology in patients with chronic kidney disease (CKD). It is one measure of the skeletal component of the systemic disorder of chronic kidney disease-min ...

Diagnosis

Histologically, it is impossible to distinguish a Brown tumor of hyperparathyroidism from other giant cell lesions of bone. Rarely a focal collection of osteoclasts (brown tumor) may occur in relation to periosteum and be indistinguishable from a peripheral giant cell granuloma (giant cell epulis). The possibility of hyperparathyroidism should be considered in patients with recurrent or multiple giant cell epulides. ; Radiographically, brown tumor may show no detectable changes or a generalized osteoporosis. Partial loss of lamina dura around the teeth may occur but is not a constant feature. Focal Lesions (Brown Tumor) present as sharply defined, round or oval radiolucent areas which may appear multilocular. Such lesions occur more frequently in mandible than maxilla

Treatment

Treatment of hyperparathyroidism is required. Parathyroidectomy usually leads to spontaneous healing of Brown tumors in primary cases.

Calcitriol Calcitriol is the active form of vitamin D, normally made in the kidney. It is also known as 1,25-dihydroxycholecalciferol. It is a hormone which binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the ...

(Rocaltrol) and

cinacalcet Cinacalcet, sold under the brand name Sensipar among others, is a medication used to treat tertiary hyperparathyroidism, parathyroid carcinoma, and primary hyperparathyroidism. Text was copied from this source which is © European Medicines Agenc ...

calcimimetic A calcimimetic is a pharmaceutical drug that mimics the action of calcium on tissues, by allosteric activation of the calcium-sensing receptor that is expressed in various human organ tissues. Calcimimetics are used to treat secondary hyperparathy ...

) are used as pharmacologic treatments.

Epidemiology

Age and gender have an effect on the incidence of these lesions; they are more prevalent in women than men (though still common in both genders), and they appear more frequently with age. Due to the standard of medical care and screening in developed countries, it is increasingly rare for primary hyperparathyroidism to present with accompanying bone disease. This is not the case in less developed nations, however, and the two conditions are more often seen together.

References

External links