Myxoma

For the atrial subtype, see Atrial myxoma. For the virus, see Myxoma virus.

"Myxomatous" redirects here. It is not to be confused with Myxomatosis.

Myxoma
Classification and external resources
Micrograph of an atrial myxoma. H&E stain.
ICD-10	D21.9d
ICD-9	212.7
ICD-O:	M8840/0
OMIM	255960
DiseasesDB	30736
eMedicine	med/186
MeSH	D009232

A myxoma (New Latin from Greek 'muxa' for mucus) is a tumor of primitive connective tissue.^[1] It is the most common primary tumor of the heart in adults, but can also occur in other locations. The phrase "myxomatous degeneration" refers to the process in which connective tissue becomes filled with mucus.

Animated image of an MRI of the heart, showing a large myxoma plunging to and fro from atrium to ventricle across the mitral valve.

A Myxoma. A gelatinous tumor can be seen attached by a narrow pedicle to the atrial septum. The myxoma has an irregular surface and nearly fills the left atrium.

Location

Myxomas are usually located in either the left or right atrium of the heart; about 86 percent occur in the left atrium.^[2]

Myxomas are typically pedunculated, with a stalk that is attached to the interatrial septum. The most common location for attachment of the stalk is the fossa ovalis region of the interatrial septum.

Diagnosis

An atrial myxoma may create an extra heart sound, audible to auscultation just after S2.

It is most seen on echocardiography, as a pedunculated mass that is heterogeneous in appearance.

A left atrial myxoma will cause an increase in Pulmonary Capillary Wedge Pressure.

The differential diagnosis include other cardiac tumors such as lipomas and rhabdomyomas (and rarely teratomas). These other tumors of the heart are typically not pedunculated, however, and are more likely to infiltrate the muscle of the heart. Cardiac magnetic resonance imaging (MRI) can help non-invasively diagnose cardiac tumors. However, diagnosis usually requires examination of a tissue sample by a pathologist.

Types^[3]

Myxoma	Margin	Vascular pattern	Cellularity	Stroma	Staining characteristics	Recurrence rate	Image (see Histology)
Cutaneous myxoma or Superficial angiomyxoma	Poor to moderately circumscribed, multilobular	Scattered thin-walled vessels	Moderately cellular, bland spindled and stellate cells, variable inflammatory cell infiltrate	Abundant mucin with clefts. Up to 30% have an associated epithelial component	Vimentin; variable staining with CD34, factor XIIIA, SMA1, MSA2 and S-100	20–30%
Intramuscular myxoma	Poorly circumscribed merges with surrounding muscle	Hypovascular variant; hypervascular variant	Hypocellular variant; hypercellular variant; bland spindle cells	Abundant mucin with cystic spaces. Hypercellular variant has strands of collagen	Vimentin; variable staining with actin, desmin, CD34	None
Juxta-articular myxoma	Poorly circumscribed infiltrates surrounding tissue	Focally vascular	Focally hypercellular, peripheral spindle cells with occasional atypical cells and mitoses	Abundant mucin, 89% of cases contain cystic spaces lined by fibrin or collagen	Vimentin; variable staining with actin, desmin, CD34	34%
Aggressive angiomyxoma	Infiltrative	Uniformly distributed medium-sized blood vessels often with prominent hyalinization	Low to moderately cellular, evenly distributed round, spindled or stellate cells	Loose myxoid to focally collagenous	Vimentin, desmin, SMA1, MSA2, estrogen and progesterone receptor	36–72%
Angiomyofibroblastoma	Well circumscribed	Abundant thin-walled blood vessels	Alternating hypercellular and hypocellular areas, perivascular condensations of spindled to epithelioid stromal cells	Collagenous to edematous with minimal mucin	Vimentin, desmin, CD34, estrogen and progesterone receptor	No recurrences reported, but rare cases of sarcomatous degeneration
Superficial acral fibromyxoma	Pushing to infiltrative	Mild to moderately accentuated vasculature	Moderately cellular, spindle and stellate cells with a storiform to fascicular pattern, variable mast cells	Myxoid to collagenous	CD34, EMA3, CD99	Recurrence rare and primarily for incompletely excised lesions
Neurothekeoma (Nerve sheath myxoma)	Well circumscribed, multilobular	Hypovascular	Moderately cellular, spindled cells in fascicles and whorls	Nests of cells separated by collagenous bundles	S-100, EMA3	47% if incompletely excised

1.^ SMA, smooth muscle actin. 2.^ MSA, muscle-specific actin. 3.^ EMA, epithelial membrane antigen.

Symptoms

Symptoms associated with cardiac myxomas are typically due to the effect of the mass of the tumor obstructing the normal flow of blood within the chambers of the heart. Because pedunculated myxomas are somewhat mobile, symptoms may only occur when the patient is in a particular position.

Some symptoms of myxoma may be associated with the release of interleukin 6 (IL-6) by the myxoma.^[4][5] High levels of IL-6 may be associated with a higher risk of embolism of the myxoma.^[6]

Symptoms of a cardiac myxoma include^[7]:

• Dyspnea on exertion
• Paroxysmal nocturnal dyspnea
• Fever
• Weight loss (see cachexia)
• Lightheadedness or syncope (Loss of consciousness)
• Hemoptysis
• Sudden death
• Tachycardia or milder heartrate, ie 75 - 100 cycl/min

Treatment

Myxomas are usually removed surgically. The surgeon removes the myxoma, along with at least 5 surrounding millimeters of atrial septum. The septum is then repaired, using material from the pericardium.

See also

• Cutaneous myxoma
• Carney complex
• Myxomatosis
• Primary tumors of the heart

References

1. ^ "Myxoma" at Dorland's Medical Dictionary
2. ^ Knepper LE, Biller J, Adams HP, Bruno A (1988). "Neurologic manifestations of atrial myxoma. A 12-year experience and review". Stroke 19 (11): 1435–40. PMID 3188128. 
3. ^ Solitary superficial angiomyxoma: an infrequent but distinct soft tissue tumor. Satter. Journal of Cutaneous Pathology, Vol 36, Issue s1, pages 56-59.
4. ^ Seino Y, Ikeda U, Shimada K. (1993). "Increased expression of interleukin 6 mRNA in cardiac myxomas". Br Heart J 69 (6): 565–7. doi:10.1136/hrt.69.6.565. PMC 1025174. PMID 8343326. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1025174. 
5. ^ Jourdan M, Bataille R, Seguin J, Zhang XG, Chaptal PA, Klein B (1990). "Constitutive production of interleukin-6 and immunologic features in cardiac myxomas". Arthritis Rheum 33 (3): 398–402. doi:10.1002/art.1780330313. PMID 1690543. 
6. ^ Wada A, Kanda t, Hayashi R, et al. (1993). "Cardiac myxoma metastasized to the brain: potential role of endogenous interleukin-6". Cardiology 83 (3): 208–11. doi:10.1159/000015180. PMID 8281536. 
7. ^ Fisher J. (1983). "Cardiac myxoma". Cardiovasc Rev Rep (4): 1195–9. 

External links

• -435814399 at GPnotebook
• 03-031b. at Merck Manual of Diagnosis and Therapy Home Edition
• Toronto General Hospital Department of Anesthesia VIRTUAL TEE pathology section: Cardiac Myxoma (with video)