Abstract
Background
Cystic myxoma is a rare morphological variant of atrial myxomas, with atypical imaging features mimicking other cystic cardiac masses.
Case Summary
A 54-year-old woman presented with palpitations and dyspnea. Echocardiography revealed a left atrial mass with a cystic component causing moderate mitral stenosis. Cardiac computed tomography and cardiac magnetic resonance confirmed a semimobile lobulated mass attached to the interatrial septum, with heterogeneous enhancement and a central cystic cavity. Surgical excision demonstrated broad-based septal attachment, and histopathology confirmed cystic myxoma. The postoperative course was uneventful, and the patient was asymptomatic at follow-up.
Discussion
Cystic myxomas are exceptionally rare and can pose diagnostic challenges given their atypical presentation and broad differential diagnosis. Multimodal imaging is essential for accurate diagnosis and surgical planning, particularly in lesions with unusual morphology.
Take-Home Messages
Multimodal imaging is pivotal in evaluating atypical cardiac masses. Early surgical excision prevents embolic and obstructive complications.
Key words: cardiac computed tomography, cardiac magnetic resonance, cystic myxoma, left atrial mass, multimodality imaging, transthoracic echocardiography
Visual Summary
History of Presentation
A 54-year-old woman was admitted with a 2-week history of palpitations and exertional dyspnea. On admission, her vital signs were within normal limits: heart rate 80 beats/min, respiratory rate 18 breaths/min, blood pressure 110/60 mm Hg, and peripheral oxygen saturation in room air of 94%. Physical examination revealed a diastolic murmur in the mitral area, more audible and intense in the left lateral decubitus position.
Electrocardiography demonstrated sinus rhythm, complete right bundle branch block, and biatrial enlargement (Figure 1A). Chest X-ray showed cardiomegaly due to left-sided chamber enlargement (Figure 1B). Blood tests revealed elevated N-terminal pro–B-type natriuretic peptide at 708 pg/mL (reference: <353 pg/mL).
Figure 1.
Comprehensive Evaluation
(A) Electrocardiogram: sinus rhythm, complete right bundle branch block, and biatrial enlargement. (B) Chest x-ray: cardiomegaly due to left-sided chamber enlargement. (C to E) Transthoracic echocardiography: well-defined mass in the left atrium with heterogeneous content and a focal cystic area, interfering with mitral valve flow and causing moderate mitral stenosis. (F to I) Cardiac computed tomography: mass located in the left atrium with hypoattenuated and heterogeneous density after contrast enhancement. (J to M) Cardiac magnetic resonance imaging: semimobile lobulated mass in the left atrium attached to the interatrial septum.
Transthoracic echocardiography (TTE) demonstrated a well-defined mass in the left atrium with heterogeneous content and a focal cystic area, which interfered with mitral valve flow, causing moderate mitral stenosis (Figures 1C to 1E, Videos 1 and 2).
Past Medical History
The patient's medical history included hypothyroidism, with no personal or family history of cardiac disease.
Differential Diagnosis
Cystic intracardiac masses include blood cysts, interatrial septal aneurysms, coronary artery aneurysms, intramural hematomas, hemangiomas, angiosarcomas, thrombi, metastatic lesions, and hydatid cysts in endemic regions.
Investigations
Cardiac computed tomography (CCT) showed a mass located in the left atrium with hypoattenuated and heterogeneous density after contrast enhancement (Figures 1F to 1I). Cardiac magnetic resonance imaging (CMR) revealed a semimobile lobulated mass measuring 6.4 × 5.3 cm in the left atrium, attached to the interatrial septum (IAS) (Figures 1J to 1M, Videos 3 to 5). The central part of the mass was cystic and hyperintense on T1 and T2 weighted, and T2 STIR sequences. The outer portion was isointense on T1-weighted sequence and hyperintense on T2-weighted and T2 STIR sequences. First-pass perfusion demonstrated partially heterogeneous enhancement within the cystic component. Late gadolinium enhancement sequences revealed a thick enhanced wall with heterogeneous peripheral enhancement, while the central portion remained largely unenhanced (Figure 2). Four-dimensional flow sequences corroborated the mass obstructing mitral inflow (Figure 3, Videos 6 to 8).
Figure 2.
Cardiac Magnetic Resonance Imaging
(A) Cine axial view showing a mass in the left atrium with a central cystic component. (B) T1-weighted image: central portion hyperintense, outer portion isointense. (C) Native T1 mapping: central portion with low values (467 ms) and outer portion with high values (2,272 ms). (D) Postcontrast T1 mapping: extracellular volume of 1% in the central portion and 47% in the outer portion. (E) T2 STIR sequence: hyperintense central and outer portions. (F) T2-weighted images: hyperintense central and outer portions. (G) T2 mapping: central portion with high values (121 ms) and outer portion with high values (220 ms). (H) T2∗ mapping: normal values in both central (64 ms) and outer (64 ms) portions. (I) First-pass perfusion: partially heterogeneous enhancement within the cystic component. (J) Late gadolinium enhancement sequence: thickened wall with heterogeneous peripheral enhancement, with the central portion largely unenhanced.
Figure 3.
4-Dimensional Flow Cardiac Magnetic Resonance Sequence
Mass obstructing mitral inflow: (A) 4-chamber view, (B) 2-chamber view, and (C) 3-chamber view.
Management
Surgical resection demonstrated broad-based attachment of the mass to the IAS. The histopathological examination revealed myxoid areas within a thick, fibrous, and compact capsule containing myxoid tissue with focal fibrinohemorrhagic changes and chronic inflammation, findings consistent with a diagnosis of cystic myxoma (Figure 4).
Figure 4.
Cystic Myxoma
(A) Macroscopic examination: mass of tumor tissue with areas of myxoid appearance, predominantly soft, gelatinous, and friable (left), with cystic tissue of myxoid characteristics (right). (B) Microscopic examination of the outer portion: spindle-shaped cells in myxoid stroma, arranged in cords. (C) Microscopic examination of the cystic wall: myxoid tissue with focal fibrinohemorrhagic changes, areas of chronic inflammation, recent hemorrhage, and hemorrhagic necrosis.
Outcome and Follow-Up
On hospitalization day 7, the patient was discharged without symptoms and remained stable throughout the follow-up surveillance.
Discussion
Cardiac myxomas represent the most common benign heart tumors, characterized by solid, round-to-oval masses attached to the IAS derived from mesenchymal cells of the septal endocardium, with the composition of a myxoid matrix that imparts a characteristic gelatinous appearance.1 Typical myxomas are masses with regular margins adherent to the left side of the IAS at the fossa ovalis level, whereas an atypical myxoma includes any morphology or location that differs from a typical lesion.2
Myxomas generally present as solid masses, although friable and cystic areas may occasionally be observed, which represent zones of necrosis and hemorrhage, particularly in polypoid variants; despite the acknowledgment of the possibility of cystic components, cystic myxomas remain atypical and infrequently reported3 given the limited number of cases in which multimodal imaging has been used for diagnosis and treatment.4,5
Cystic cardiac tumors are extremely rare, with clinical diagnosis generally based on echocardiography, although in certain circumstances this modality may prove inconclusive. Currently, the most widely accepted mechanism for cyst formation involves degeneration of the myxomatous stroma accompanied by intratumoral hemorrhage.6 Cystic myxoma represents an exceptionally rare morphological variant, differing from the typical solid, round, or polypoid mass arising from the interatrial septum.1,7 Published reports described its incidental identification on TTE, with only a handful of cases documented in the literature.7
Clinical presentation is often nonspecific, and embolic events remain a concern for up to 50% of myxoma cases regardless of morphology. Coronary steal syndrome may result from feeding arteries from coronary vessels. The stability of the cystic cavity, often filled with blood, may depend on the presence of a drainage orifice allowing outflow.7
In cystic myxoma, TTE typically reveals an echolucent, well-defined mass with anechoic content attached to the atrial septum by a narrow stalk, which may prolapse into the mitral valve during diastole, causing partial obstruction.7 Transesophageal echocardiography has superior resolution, enabling an accurate assessment of mass attachment and valve involvement, as well as dynamic behavior.2,7 Nevertheless, cystic morphology can mimic other entities such as congenital blood cyst or hydatid cysts, particularly when multiple cavities are present.5,8 Contrast echocardiography may assist in distinguishing vascular tumors from thrombi, though it cannot reliably determine their histological subtype.2
CMR is the reference standard for tissue characterization in cardiac masses.2 In cystic myxoma, the fluid component appears hypointense on T1-weighted images and hyperintense on T2-weighted images, while the solid portion is hypointense on both sequences. First-pass perfusion may demonstrate progressive enhancement within the cystic space, consistent with hemorrhagic content, without appreciable enhancement in the solid component. Late gadolinium enhancement sequences show persistent enhancement in cystic areas and no enhancement in solid tissue. High inversion time imaging excludes thrombus.1 CMR also accurately defines the tumor's attachment site and excludes myocardial infiltration, critical for surgical planning.2
CCT provides information complementary to CMR, including precise anatomical relationships, calcification detection, and coronary artery evaluation.2 In cystic myxoma, CCT may show a low-attenuation cavity and heterogeneous enhancement of the solid portion after contrast.2,7 CCT is particularly useful when CMR is contraindicated or unavailable, aiding in the exclusion of obstructive coronary disease before surgery and providing additional value in assessing extracardiac extension and guiding surgical planning when masses are adjacent to coronary vessels.2
Despite advances in multimodality imaging, preoperative diagnosis of cystic myxoma remains challenging given the absence of pathognomonic features.1,7 Histopathology remains essential for definitive diagnosis, demonstrating typical myxoma features in the cyst wall and absence of endothelial lining.7 Microscopy typically shows polygonal-to-stellate lepidic cells arranged in cords and nests within a myxoid stroma, with degenerative changes corresponding to cystic transformation.1
The management of cystic myxoma mirrors that of the typical form, with prompt surgical excision recommended to prevent complications such as embolism, valve obstruction, and sudden death.1 Complete resection is both diagnostic and therapeutic, eliminating the need for preoperative biopsy in resectable left atrial lesions.2 Postoperative follow-up with periodic TTE is advised, given recurrence rates of 5% to 15%, particularly in familial cases.9
From a broader perspective, the lack of standardized guidelines for the imaging work-up of cardiac masses has led to variability in clinical practice, with possible underuse of advanced modalities in smaller centers and overuse in tertiary centers. A structured algorithm for integrating echocardiography, CMR, and CCT according to lesion features, patient comorbidities, and institutional resources could improve diagnostic accuracy and optimize resource use.2
Conclusions
Cystic myxoma is a rare morphological variant of benign atrial tumors that poses diagnostic challenges owing to its atypical appearance and broad differential diagnosis. Multimodal imaging is essential for accurate evaluation, with echocardiography providing detection and hemodynamic assessment, CMR offering tissue characterization, and CCT defining anatomy and guiding surgical planning.
Visual Summary.
Giant Cystic Left Atrial Myxoma: Multimodal Imaging Assessment
Funding Support and Author Disclosures
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Take-Home Messages
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Cystic myxoma is an exceptionally rare variant of atrial myxomas.
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Multimodal cardiac imaging is essential for accurate diagnosis and surgical guidance.
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Early surgical excision prevents embolic and obstructive complications.
Acknowledgments
The authors express their sincere gratitude to A. Aranda-Fraustro and M.M. Mata-Pacheco of the Pathology Department at the Instituto Nacional de Cardiología Ignacio Chávez for kindly providing the macroscopic and microscopic pathology images.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
Appendix
For supplemental videos, please see the online version of this paper.
Appendix
Transthoracic Echocardiography Long-Axis View Showing Cystic Myxoma
Transthoracic Echocardiography 4-Chamber View Showing Cystic Myxoma With Mitral Inflow Acceleration on Color Doppler
CMR 4-Chamber Cine View
CMR 2-Chamber Cine View
CMR 3-Chamber Cine View
Four-Dimensional Flow CMR 3-Chamber Cine View Showing Cystic Myxoma With Mitral Inflow Acceleration
Four-Dimensional Flow CMR 4-Chamber Cine View Showing Cystic Myxoma With Mitral Inflow Acceleration
Four-Dimensional Flow CMR 2-Chamber Cine View Showing Cystic Myxoma With Mitral Inflow Acceleration
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Associated Data
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Supplementary Materials
Transthoracic Echocardiography Long-Axis View Showing Cystic Myxoma
Transthoracic Echocardiography 4-Chamber View Showing Cystic Myxoma With Mitral Inflow Acceleration on Color Doppler
CMR 4-Chamber Cine View
CMR 2-Chamber Cine View
CMR 3-Chamber Cine View
Four-Dimensional Flow CMR 3-Chamber Cine View Showing Cystic Myxoma With Mitral Inflow Acceleration
Four-Dimensional Flow CMR 4-Chamber Cine View Showing Cystic Myxoma With Mitral Inflow Acceleration
Four-Dimensional Flow CMR 2-Chamber Cine View Showing Cystic Myxoma With Mitral Inflow Acceleration