Unicameral bone cyst

Last updated
Unicameral bone cyst
Other namesSolitary bone cyst, [1] [2] unicameral bone cyst (not recommended) [1]
Cisti ossea semplice RM T2.jpg
MRI scan: simple bone cyst humerus of a 13 year old boy
Specialty Orthopedics
Symptoms Pain, swelling, reduced movement, pathological fracture or no symptoms [1]
CausesUnknown [1]
Diagnostic method Medical imaging [1]
FrequencyAge less than 20 years. M:F ratio: 2:1 [1]

A unicameral bone cyst, also known as a simple bone cyst, is a cavity filled with a yellow-colored fluid. [1] [3] It is considered to be benign since it does not spread beyond the bone. [4] Unicameral bone cysts can be classified into two categories: active and latent. [4] An active cyst is adjacent to the epiphyseal plate and tends to grow until it fills the entire diaphysis, the shaft, of the bone; depending on the invasiveness of the cyst, it can cause a pathological fracture or even destroy the epiphyseal plate leading to the permanent shortening of the bone. [4]

Contents

A latent cyst is located away from the epiphyseal plate and is more likely to heal with treatment. [4] It is typically diagnosed in under 20 year olds. [1] Although unicameral bone cysts can form in any bone structure, it is predominantly found in the proximal humerus and proximal femur; additionally, it affects males twice as often as females. [1] [3]

Treatment options for unicameral bone cysts include invasive approaches such as injections, curettage and surgical fixation, and non-invasive procedures including observation to see if it does not get worse or resolves on its own, plaster casting or restricted activity. [5]

Signs and symptoms

Most unicameral bone cysts do not cause any symptoms and are discovered as accidental findings on radiographs or CT scans made for other reasons. [1] Large lesions can cause nearby areas of bone to thin, which may result in a fracture and cause pain. [1] [6]

Cause

There is not a specific theory behind the etiology of the unicameral bone cyst, however, according to many researchers and doctors, there is a commonly known theory hypothesized by Jonathan Cohen in 1970. [3] Cohen studied interstitial fluid in six children undergoing treatment for unicameral bone cysts. [3] He believed that the chemical composition of the fluid found in the bone cyst was similar to the chemical make-up in serum. [6] Cohen theorized that the unicameral bone cyst occurs when interstitial fluids in cancellous bones quickly accumulate in one region from blockage. [6]

One of the other theories is that the cysts result from a disorder of the growth plate. Another is that the cysts result from problems with circulation that are caused by a developmental anomaly in the veins of the affected bone. The role trauma plays in the development of these cysts is unknown. Some speculate that repeated trauma puts the bone at risk for developing a bone cyst. This, however, has not been proven. [3]

Recently, some of these tumors have been found to contain cells that express the FUS-NFATC2 or EWSR1-NFATC2 fusion gene. [7] (Fusion genes are formed from two previously independent genes that become united due to a chromosome translocation, deletion of some genetic material in a chromosome, or chromosomal inversion. [7] [8] These two fusion genes are described in FET gene family.) A recent study reported that the neoplastic cells in these cysts expressed a FUS-NFATC2 fusion gene in four and a EWSR1-NFATC2 fusion gene in two of nine test cases. [9] It is suggested that the presence of these fusion genes indicates that SEC is a true neoplasm. [7]

Diagnosis

X-rays

Unicameral bone cysts are found incidentally on X-rays. About 90 to 95% of the lesion is found in metaphysics of long bones. The cyst is centered, oblong in shape along the long axis of a long bone. Rarely, they are large and multicameral and are found in diaphysis. When fracture is present, there may be a small bone fragment migrated in the cystic fluid. This is called "fallen fragment sign" which is diagnostic of unicameral bone cyst. Besides, a bubble migrating upwards (known as "rising bubble sign") is another feature suggesting of unicameral bone cyst. [10]

Computerized tomography (CT) Scan

CT scan shows a thin-walled lesion with pseudo septum (incomplete septum or a septum with perforations that allows communications between two chambers). CT scan is used to assess cyst wall thickness and risk of fracture. [10]

Magnetic Resonance Imaging (MRI)

Magnetic resonance imaging scans are used to identify the precise location of the cyst, to see how aggressive the disease is, and to determine the actual shape and size. [4] The MRI uses a combination of magnets and radio-frequencies to produce various detailed, computerized images of the cyst and its surrounding body structures. [4]

Bone scans

a nuclear imaging method to evaluate any degenerative and/or arthritic changes in the joints; to detect bone diseases and tumors; to determine the cause of bone pain or inflammation. This test is to rule out other cysts (which are quite unusual) [3]

Treatment

If there is a high probability of a fracture resulting from the unicameral bone cyst, then surgical treatment is necessary. [4] Specific methods can be determined by the physician based upon the patient's age, medical history, tolerance for certain medical procedures or medicine, health, and extremity of the disease, [4] however, the evidence to support one treatment option over another is very weak. [5] The treatment can involve or incorporate one or more of the following surgical methods, which are performed by a pediatric orthopedic surgeon: [4]

Surgeons create an incision or opening in the bone to drain out the fluids inside the cyst. [4] After the fluid is drained, a curette is used to scrape the lining tissue out of the lesion. [4]
Bone grafting is proceeded with after curettage; the empty cavity is transplanted with donor bone tissue, bone chips taken from another bone, or artificial material. [4]
An injection of methylprednisolone acetate into the lesion helps reduce the levels of prostaglandin. [4] Prostaglandin is a fatty acid that reduces cyst's ability to be reabsorbed into the bone. [4] To begin an operation using steroids, biopsy needles are placed into the cyst and the interstitial fluids are drained. [4] The cyst is then filled with radiographic contrast to determine the volume and shape of the cyst. [4] If the cyst can be filled, it will be injected with methylprednisolone acetate in several intervals for a time span of six to twelve months. [4] Once the level of prostaglandin decreases, the cyst will be reabsorbed into the bone and disappear. [4] Treatments using steroid injections are preferred over curettage, but there are few risks from the method, which are limited to infection, fracture, and reappearance of the cyst. [4]

If a person needs to be treated with surgery, a standard surgical procedure would be called for; the person would be resting in Fowler's position, a semi-sitting position, under general anesthesia. [11] The exact size, shape, and distance between the acromion to the midpoint of the cyst are measured by a digital radiograph or MRI scan. [11] A small, longitudinal skin incision, about 1 cm long, is made at the center of the cyst. [11] Next, by using a trephine or drill bit, a small aperture is made inside the incision. [11] Fluids contained in the cyst are drained and curved, metal impactors are used to break any septa, or membranes, within the cyst. [11] Curettes are then used to remove the entire cyst from the diaphysis. [11] After the removal of the cystic membrane, a 95% ethanol solution is injected into the cavity to produce a chemical cauterization to burn away any residual active membrane for 30 seconds and then aspirated. [11] Saline solution is then immediately injected into the cavity to wash out any residual ethanol solution and to mitigate any damage to healthy tissue; this irrigation process of ethanol and saline solutions is repeated for another 2 to 3 times. [11] A curved impactor is inserted into the cavity and used to penetrate the boundary between the cyst and bone marrow; the intentional penetrations will allow bone marrow cells to migrate into the cavity to produce a source of osteoinductive cells, cells that induce bony growth. [11] Furthermore, the cavity is completely filled with bone graft substitute, such as calcium sulfate. [11] Finally, one cannulated screw is placed into the aperture. [11]

Related Research Articles

<span class="mw-page-title-main">Metaphysis</span> Neck portion of a long bone between the epiphysis and the diaphysis

The metaphysis is the neck portion of a long bone between the epiphysis and the diaphysis. It contains the growth plate, the part of the bone that grows during childhood, and as it grows it ossifies near the diaphysis and the epiphyses. The metaphysis contains a diverse population of cells including mesenchymal stem cells, which give rise to bone and fat cells, as well as hematopoietic stem cells which give rise to a variety of blood cells as well as bone-destroying cells called osteoclasts. Thus the metaphysis contains a highly metabolic set of tissues including trabecular (spongy) bone, blood vessels, as well as marrow adipose tissue (MAT).

<span class="mw-page-title-main">Ameloblastoma</span> Medical condition

Ameloblastoma is a rare, benign or cancerous tumor of odontogenic epithelium much more commonly appearing in the lower jaw than the upper jaw. It was recognized in 1827 by Cusack. This type of odontogenic neoplasm was designated as an adamantinoma in 1885 by the French physician Louis-Charles Malassez. It was finally renamed to the modern name ameloblastoma in 1930 by Ivey and Churchill.

<span class="mw-page-title-main">Enchondroma</span> Medical condition

Enchondroma is a type of benign bone tumor belonging to the group of cartilage tumors. There may be no symptoms, or it may present typically in the short tubular bones of the hands with a swelling, pain or pathological fracture.

<span class="mw-page-title-main">Giant-cell tumor of bone</span> Medical condition

Giant-cell tumor of the bone (GCTOB), is a relatively uncommon tumor of the bone. It is characterized by the presence of multinucleated giant cells. Malignancy in giant-cell tumor is uncommon and occurs in about 2% of all cases. However, if malignant degeneration does occur, it is likely to metastasize to the lungs. Giant-cell tumors are normally benign, with unpredictable behavior. It is a heterogeneous tumor composed of three different cell populations. The giant-cell tumour stromal cells (GCTSC) constitute the neoplastic cells, which are from an osteoblastic origin and are classified based on expression of osteoblast cell markers such as alkaline phosphatase and osteocalcin. In contrast, the mononuclear histiocytic cells (MNHC) and multinucleated giant cell (MNGC) fractions are secondarily recruited and comprise the non-neoplastic cell population. They are derived from an osteoclast-monocyte lineage determined primarily by expression of CD68, a marker for monocytic precursor cells. In most patients, the tumors are slow to develop, but may recur locally in as many as 50% of cases.

<span class="mw-page-title-main">Aneurysmal bone cyst</span> Medical condition

Aneurysmal bone cyst (ABC) is a non-cancerous bone tumor composed of multiple varying sizes of spaces in a bone which are filled with blood. The term is a misnomer, as the lesion is neither an aneurysm nor a cyst. It generally presents with pain and swelling in the affected bone. Pressure on neighbouring tissues may cause compression effects such as neurological symptoms.

<span class="mw-page-title-main">Central giant-cell granuloma</span> Medical condition

Central giant-cell granuloma (CGCG) is a localised benign condition of the jaws. It is twice as common in females and is more likely to occur before age 30. Central giant-cell granulomas are more common in the anterior mandible, often crossing the midline and causing painless swellings.

<span class="mw-page-title-main">Periapical cyst</span> Medical condition

Commonly known as a dental cyst, the periapical cyst is the most common odontogenic cyst. It may develop rapidly from a periapical granuloma, as a consequence of untreated chronic periapical periodontitis.

<span class="mw-page-title-main">Odontogenic keratocyst</span> Medical condition

An odontogenic keratocyst is a rare and benign but locally aggressive developmental cyst. It most often affects the posterior mandible and most commonly presents in the third decade of life. Odontogenic keratocysts make up around 19% of jaw cysts. Despite its more common appearance in the bone region, it can affect soft tissue.

<span class="mw-page-title-main">Glandular odontogenic cyst</span> Human jaw cyst

A glandular odontogenic cyst (GOC) is a rare and usually benign odontogenic cyst developed at the odontogenic epithelium of the mandible or maxilla. Originally, the cyst was labeled as "sialo-odontogenic cyst" in 1987. However, the World Health Organization (WHO) decided to adopt the medical expression "glandular odontogenic cyst". Following the initial classification, only 60 medically documented cases were present in the population by 2003. GOC was established as its own biological growth after differentiation from other jaw cysts such as the "central mucoepidermoid carcinoma (MEC)", a popular type of neoplasm at the salivary glands. GOC is usually misdiagnosed with other lesions developed at the glandular and salivary gland due to the shared clinical signs. The presence of osteodentin supports the concept of an odontogenic pathway. This odontogenic cyst is commonly described to be a slow and aggressive development. The inclination of GOC to be large and multilocular is associated with a greater chance of remission. GOC is an infrequent manifestation with a 0.2% diagnosis in jaw lesion cases. Reported cases show that GOC mainly impacts the mandible and male individuals. The presentation of GOC at the maxilla has a very low rate of incidence. The GOC development is more common in adults in their fifth and sixth decades.

<span class="mw-page-title-main">Chondroblastoma</span> Medical condition

Chondroblastoma is a rare, benign, locally aggressive bone tumor that typically affects the epiphyses or apophyses of long bones. It is thought to arise from an outgrowth of immature cartilage cells (chondroblasts) from secondary ossification centers, originating from the epiphyseal plate or some remnant of it.

<span class="mw-page-title-main">Myxoid liposarcoma</span> Medical condition

A myxoid liposarcoma is a malignant adipose tissue neoplasm of myxoid appearance histologically.

<span class="mw-page-title-main">Clear cell sarcoma</span> Rare form of cancer

Clear cell sarcoma is a sub-type of a rare form of cancer called a sarcoma. It is known to occur mainly in the soft tissues and dermis. Rare forms were thought to occur in the gastrointestinal tract before they were discovered to be different and redesignated as gastrointestinal neuroectodermal tumors.

<span class="mw-page-title-main">Bone cyst</span> Medical condition

A bone cyst or geode is a cyst that forms in bone.

Extraskeletal myxoid chondrosarcoma (EMC) is a rare low-grade malignant mesenchymal neoplasm of the soft tissues, that differs from other sarcomas by unique histology and characteristic chromosomal translocations. There is an uncertain differentiation and neuroendocrine differentiation is even possible.

Pseudocyst of the auricle, also known as auricular pseudocyst, endochondral pseudocyst, cystic chondromalacia, intracartilaginous auricular seroma cyst, and benign idiopathic cystic chondromalacia, is a cutaneous condition characterized by a fluctuant, tense, noninflammatory swelling on the upper half of the ear, known as the auricle or pinna. Pseudocysts of the auricle are nontender, noninflammatory cystic lesions that progress over a 4- to 12-week period, ranging from 1 to 5 cm in diameter. They are usually unilateral, often on the right ear, but can also present bilaterally.

A cyst is a pathological epithelial lined cavity that fills with fluid or soft material and usually grows from internal pressure generated by fluid being drawn into the cavity from osmosis. The bones of the jaws, the mandible and maxilla, are the bones with the highest prevalence of cysts in the human body. This is due to the abundant amount of epithelial remnants that can be left in the bones of the jaws. The enamel of teeth is formed from ectoderm, and so remnants of epithelium can be left in the bone during odontogenesis. The bones of the jaws develop from embryologic processes which fuse, and ectodermal tissue may be trapped along the lines of this fusion. This "resting" epithelium is usually dormant or undergoes atrophy, but, when stimulated, may form a cyst. The reasons why resting epithelium may proliferate and undergo cystic transformation are generally unknown, but inflammation is thought to be a major factor. The high prevalence of tooth impactions and dental infections that occur in the bones of the jaws is also significant to explain why cysts are more common at these sites.

<span class="mw-page-title-main">Low-grade fibromyxoid sarcoma</span> Medical condition

Low-grade fibromyxoid sarcoma (LGFMS) is a rare type of low-grade sarcoma first described by H. L. Evans in 1987. LGFMS are soft tissue tumors of the mesenchyme-derived connective tissues; on microscopic examination, they are found to be composed of spindle-shaped cells that resemble fibroblasts. These fibroblastic, spindle-shaped cells are neoplastic cells that in most cases of LGFMS express fusion genes, i.e. genes composed of parts of two different genes that form as a result of mutations. The World Health Organization (2020) classified LGFMS as a specific type of tumor in the category of malignant fibroblastic and myofibroblastic tumors.

<span class="mw-page-title-main">Angiomatoid fibrous histiocytoma</span> Type of tumor which affects children and adolescents

Angiomatoid fibrous histiocytoma(AFH) is a rare soft tissue cancer that affects children and young adults.

Sclerosing epithelioid fibrosarcoma (SEF) is a very rare malignant tumor of soft tissues that on microscopic examination consists of small round or ovoid neoplastic epithelioid fibroblast-like cells, i.e. cells that have features resembling both epithelioid cells and fibroblasts. In 2020, the World Health Organization classified SEF as a distinct tumor type in the category of malignant fibroblastic and myofibroblastic tumors. However, current studies have reported that low-grade fibromyxoid sarcoma (LGFMS) has many clinically and pathologically important features characteristic of SEF; these studies suggest that LGSFMS may be an early form of, and over time progress to become, a SEF. Since the World Health Organization has classified LGFMS as one of the malignant fibroblastic and myofibroblastic tumors that is distinctly different than SEF, SEF and LGFMS are here regarded as different tumor forms.

The FET protein family consists of three similarly structured and functioning proteins. They and the genes in the FET gene family which encode them are: 1) the EWSR1 protein encoded by the EWSR1 gene located at band 12.2 of the long arm of chromosome 22; 2) the FUS protein encoded by the FUS gene located at band 16 on the short arm of chromosome 16; and 3) the TAF15 protein encoded by the TAF15 gene located at band 12 on the long arm of chromosome 7 The FET in this protein family's name derives from the first letters of FUS, EWSR1, and TAF15.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 WHO Classification of Tumours Editorial Board, ed. (2020). "3. Bone tumours: simple bone cyst". Soft Tissue and Bone Tumours: WHO Classification of Tumours. Vol. 3 (5th ed.). Lyon (France): International Agency for Research on Cancer. pp. 467–469. ISBN   978-92-832-4503-2.
  2. ↑ "ICD-11 - ICD-11 for Mortality and Morbidity Statistics". icd.who.int. Retrieved 25 June 2021.
  3. 1 2 3 4 5 6 Mehlman, Charles T. "Unicameral Bone Cyst". Medscape Reference. Retrieved 17 March 2012.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 "Simple Bone Cyst (unicameral)". Children's Hospital Boston. Retrieved 22 March 2012.
  5. 1 2 Zhao, Jia-Guo; Wang, Jia; Huang, Wan-Jie; Zhang, Peng; Ding, Ning; Shang, Jian (2017-02-04). "Interventions for treating simple bone cysts in the long bones of children". The Cochrane Database of Systematic Reviews. 2 (2): CD010847. doi:10.1002/14651858.CD010847.pub3. ISSN   1469-493X. PMC   6464391 . PMID   28158933.
  6. 1 2 3 Cohen, Jonathan (1970). "Etiology of Simple Bone Cyst". The Journal of Bone and Joint Surgery. 52 (7): 1493–97. doi:10.2106/00004623-197052070-00030. PMID   5472904 . Retrieved 23 March 2012.
  7. 1 2 3 Flucke U, van Noesel MM, Siozopoulou V, Creytens D, Tops BB, van Gorp JM, Hiemcke-Jiwa LS (June 2021). "EWSR1-The Most Common Rearranged Gene in Soft Tissue Lesions, Which Also Occurs in Different Bone Lesions: An Updated Review". Diagnostics (Basel, Switzerland). 11 (6): 1093. doi: 10.3390/diagnostics11061093 . PMC   8232650 . PMID   34203801.
  8. ↑ Boone MA, Taslim C, Crow JC, Selich-Anderson J, Watson M, Heppner P, Hamill J, Wood AC, Lessnick SL, Winstanley M (August 2021). "Identification of a novel FUS/ETV4 fusion and comparative analysis with other Ewing sarcoma fusion proteins". Molecular Cancer Research. doi:10.1158/1541-7786.MCR-21-0354. PMC   8568690 . PMID   34465585. S2CID   237373339.
  9. ↑ Pižem J, Šekoranja D, Zupan A, Boštjančič E, Matjašič A, Mavčič B, Contreras JA, Gazič B, Martinčič D, Snoj Ž, Limpel Novak KA, Salapura V (December 2020). "FUS-NFATC2 or EWSR1-NFATC2 Fusions Are Present in a Large Proportion of Simple Bone Cysts". The American Journal of Surgical Pathology. 44 (12): 1623–1634. doi:10.1097/PAS.0000000000001584. PMID   32991339. S2CID   222166961.
  10. 1 2 Mascard, E.; Gomez-Brouchet, A.; Lambot, K. (February 2015). "Bone cysts: Unicameral and aneurysmal bone cyst". Orthopaedics & Traumatology: Surgery & Research. 101 (1): S119–S127. doi: 10.1016/j.otsr.2014.06.031 . PMID   25579825.
  11. 1 2 3 4 5 6 7 8 9 10 11 Hou, Hsien-Yang; Karl Wu; Chen-Ti Wang; Shun-Min Chang; Wei-Hsin Lei; Rong-Sen Yang (2011). "Treatment of Unicameral Bone Cyst: Surgical Technique". The Journal of Bone and Joint Surgery. American Volume. 93: 92–99. doi:10.2106/JBJS.J.01123. PMID   21411690.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.