Cardiac Myxoma: Review and Update of Contemporary Immunohistochemical Markers and Molecular Pathology

From the archives of MD Anderson Cancer Center. Mesothelial/monocytic incidental cardiac excrescence with a review of the literature

Mesothelial/monocytic incidental cardiac excrescence (MICE) is a rare benign lesion composed of monocytes and mesothelial cells that is most often encountered during cardiothoracic surgery. We describe a case in a 71-year-old man with known aortic valve stenosis who presented with gradual onset dyspnea over a few weeks, made worse with minimal exertion. A transesophageal echocardiogram revealed severe aortic stenosis and mild pericardial effusion. The patient underwent aortic valve replacement, coronary artery bypass, and amputation of the left atrial appendage. Histological examination of a 0.8 cm blood clot received along with the atrial appendage showed an aggregation of bland cells with features of monocytes associated with small strands and nodules of mesothelial cells, fat cells, fibrin and a minute fragment of bone. Immunohistochemical analysis showed that the monocytic cells were positive for CD4 and CD68 (strong) and negative for calretinin and keratin. By contrast, the mesothelial cells were positive for calretinin and keratin and negative for all other markers. In sum, the morphologic and immunohistochemical findings support the diagnosis of MICE. Based on our review of the literature, about 60 cases of MICE have been reported previously which we have tabulated. We also discuss the differential diagnosis.

Two cases of atrial myxoma with calcification and ossification as the main features

BACKGROUND

Cardiac myxomas are the most common type of primary cardiac tumors in adults, but they can have variable features that make them difficult to diagnose. We report two cases of atrial myxoma with calcification or ossification, which are rare pathological subgroups of myxoma.

CASE PRESENTATION

A 47-year-old woman and a 35-year-old man presented to our hospital with different symptoms. Both patients had a history of chronic diseases. Transthoracic and transesophageal echocardiography revealed a mass in the left or right atrium, respectively, with strong echogenicity and echogenic shadows. The masses were suspected to be malignant tumors with calcification or ossification. Contrast transthoracic echocardiography(cTEE) showed low blood supply within the lesions. The patients underwent surgical resection of the atrial mass, and the pathology confirmed myxoma with partial ossification or massive calcification.

CONCLUSION

We report two rare cases of atrial myxoma with calcification or ossification and analyze their ultrasonographic features. Transthoracic echocardiography and cTEE can provide valuable information for the diagnosis and management of such mass. However, distinguishing calcification and ossification in myxoma from calcification in malignant tumors is challenging. More studies are needed to understand the pathogenesis and imaging characteristics of these myxoma variants.

A case of cardiac undifferentiated pleomorphic sarcoma in late pregnancy: A case report

Cardiac tumors are uncommon and most of them are benign. Although cases of malignant cardiac tumors are rare, it is still necessary to improve awareness in both clinical and pathological diagnosis. Since cardiac tumors often have a high degree of malignancy, it is vital to determine what form of intervention can increase recurrence-free survival and overall survival. In this paper, we report on a 42-year-old woman in the third trimester of pregnancy who had a cardiac undifferentiated pleomorphic sarcoma. According to her medical history, the patient had never had a cardiac tumor or any other disease. She was treated surgically and a left atrial mass was removed immediately after cesarean section. No other treatments were applied after the surgery, and, unfortunately, the tumor reoccurred 6 months later. We reviewed some literature and found one case in which the patient was treated using radiotherapy and survived for another 2 years after the third tumor recurrence. This suggests that neoadjuvant therapy effectively improves the survival rates of such patients.

Myxoma with rich blood supply in the left atrium

Cardiac myxoma is the most common primary benign cardiac tumors, mostly found in the left atrium. It was previously reported that the main component of myxoma was myxoid stroma riched in acid-mucopolysaccharide, the blood vessels in which were sparsely distributed, being characterized as hypovascular tumor by contrast echocardiography (CE) and computed tomography angiography (CTA). There are few reports of myxoma with rich blood supply and we report one in the left atrium.

Resolving the heterogeneous tumour microenvironment in cardiac myxoma through single-cell and spatial transcriptomics

BACKGROUND

Cardiac myxoma (CM) is the most common (58%-80%) type of primary cardiac tumours. Currently, there is a need to develop medical therapies, especially for patients not physically suitable for surgeries. However, the mechanisms that shape the tumour microenvironment (TME) in CM remain largely unknown, which impedes the development of targeted therapies. Here, we aimed to dissect the TME in CM at single-cell and spatial resolution.

METHODS

We performed single-cell transcriptomic sequencing and Visium CytAssist spatial transcriptomic (ST) assays on tumour samples from patients with CM. A comprehensive analysis was performed, including unsupervised clustering, RNA velocity, clonal substructure inference of tumour cells and cell-cell communication.

RESULTS

Unsupervised clustering of 34 759 cells identified 12 clusters, which were assigned to endothelial cells (ECs), mesenchymal stroma cells (MSCs), and tumour-infiltrating immune cells. Myxoma tumour cells were found to encompass two closely related phenotypic states, namely, EC-like tumour cells (ETCs) and MSC-like tumour cells (MTCs). According to RNA velocity, our findings suggest that ETCs may be directly differentiated from MTCs. The immune microenvironment of CM was found to contain multiple factors that promote immune suppression and evasion, underscoring the potential of using immunotherapies as a treatment option. Hyperactive signals sent primarily by tumour cells were identified, such as MDK, HGF, chemerin, and GDF15 signalling. Finally, the ST assay uncovered spatial features of the subclusters, proximal cell-cell communication, and clonal evolution of myxoma tumour cells.

CONCLUSIONS

Our study presents the first comprehensive characterisation of the TME in CM at both single-cell and spatial resolution. Our study provides novel insight into the differentiation of myxoma tumour cells and advance our understanding of the TME in CM. Given the rarity of cardiac tumours, our study provides invaluable datasets and promotes the development of medical therapies for CM.

Crosstalk between KIF1C and PRKAR1A in left atrial myxoma

Cardiac myxoma (CM) is the most common benign cardiac tumor, and most CMs are left atrial myxomas (LAMs). Six variations of KIF1C, c.899 A > T, c.772 T > G, c.352 A > T, c.2895 C > T, c.3049 G > A, and c.*442_*443dup in left atrial myxoma tissues are identified by whole-exome sequencing (WES) and Sanger sequencing. RNA-seq and function experiments show the reduction of the expression of KIF1C and PRKAR1A caused by rare variations of KIF1C. KIF1C is observed to be located in the nucleus, bind to the promoter region of PRKAR1A, and regulate its transcription. Reduction of KIF1C decreases PRKAR1A expression and activates the PKA, which causes an increase in ERK1/2 phosphorylation and SRC-mediated STAT3 activation, a reduction of CDH1, TP53, CDKN1A, and BAX, and eventually promotes tumor formation both in vitro and in vivo. The results suggest that inhibition of KIF1C promotes the pathogenesis of LAM through positive feedback formed by the crosstalk between KIF1C and PRKAR1A.

Atrial Myxoma Presenting With Hemorrhage and Multifocal Infarcts in the Brain of a 59-Year-Old Man: An Uncommon Outcome for the Most Common Primary Heart Neoplasm

Atrial myxomas are the most common primary neoplasm of the heart. Due to their mass effect, they may lead to dysfunction of the heart or mitral valve. Rarely, neoplastic fragments may embolize or a thrombus secondary to stasis may form, which can infarct downstream structures (e.g., the brain). We report the case of a 59-year-old man presenting with headaches, visual changes, and word-finding difficulty secondary to multifocal brain lesions that were identified on computed tomography and magnetic resonance imaging. After an extensive workup, the etiology of the patient's neurological symptoms was determined to be embolization from a large atrial myxoma (2.3x3.5 cm). Histologic and immunohistochemical examination of the atrial myxoma and largest brain lesion yielded similarities, including the presence of spindle-shaped and stellate cells, myxoid regions, Alcian blue pH 2.5 positivity, calretinin positivity, cluster of differentiation 34 (CD34) positivity, and cluster of differentiation 68 (CD68) negativity. This case was remarkable due to the patient's late presentation, the large size of the atrial myxoma, the presence of abundant cerebral hemisphere and cerebellar lesions, and the histologic comparison of the heart and brain lesions. Atrial myxomas have been reported from childhood to late adulthood and when symptoms typically present clinically due to the mass effect. However, neurologic manifestations from embolization or thrombus formation can occur, as in the present case. Therefore, considering the presence of atrial myxomas is important in patients with neurologic manifestations and heart murmurs.

Massive hemoptysis as a sole presentation of left atrial myxoma

Diagnosis of myxoma can be difficult given its variable presentation and while adopting common sense in diagnosing this condition, physicians should also be aware of atypical presentations. Herein we present a 47-year-old heavy smoker presented with massive blood-stained expectoration. He was later diagnosed with cardiac myxoma and managed accordingly.

Cardiac Myxomas As Chameleons: A Scoping Review of Their Paraneoplastic Presentations

This scoping review aims to explore the relationship between cardiac myxomas (CMs) and paraneoplastic syndromes (PS). CMs are the most common tumors in the heart, with the majority located in the left atrium, and are often associated with a triad of obstructive, embolic, and constitutional symptoms. However, they can also present with unrelated symptoms that are part of a PS. This study performed a thorough literature search of 11 databases and included 12 papers in the final review. All of the patients were diagnosed with atrial myxoma, which initially presented as a PS. Surgery was the curative measure in all cases and resulted in remission in every case, with patients reporting resolution of symptoms at follow-up. The majority of patients in the study were female, with comorbid rheumatologic conditions often present. This study highlights the heterogeneity of presentations of CMs and their associated PS.

Case report: Multiple brain metastases of atrial myxoma: Clinical experience and literature review

Myxoma is the most common type of benign cardiac tumor in adults, and it has a strong tendency to embolize or metastasize to distant organs. Patients with multiple brain metastases have rarely been seen in clinics; hence, standard treatment protocols for multimyxoma metastasis in the brain have not been established. We present the case of a 47-year-old female who had convulsions in the right hand and repeated seizures. Computed tomography revealed multiple tumor sites in her brain. Craniotomy was conducted to remove the tumor sites. However, recurrent brain tumors and unexpected cerebral infarctions occurred frequently shortly after the treatment because the cardiac myxoma had not been treated due to the patient's personal concerns. The myxoma was resected by gamma knife radiosurgery, and temozolomide was given prior to cardiac surgery. There has been no evidence of tumor recurrence from the 2 years following the surgery until the present. This case highlights the importance of prioritizing cardiac lesions over cerebral lesions; if a cerebral metastasis has been found, it is likely that the cardiac myxoma is already unstable, with high rates of spread and metastasis. Therefore, it is unwise to treat metastasis sites before the cardiac myxoma. Additionally, the case suggests that gamma knife radiosurgery combined with temozolomide is effective as treatment for multiple myxoma metastasis in the brain. Compared with conventional cerebral surgery, gamma knife radiosurgery is safer, causes less bleeding, and requires a shorter time for recovery.

Resection of Orbital Myxoma With Magnetic Resonance Imaging Evidence of Ethmoid Sinus Origin: Case Report and Review of 20 Patients in the Literature

A 41-year-old woman showed a palpable mass at the superonasal orbital edge on the right side. Magnetic resonance imaging demonstrated a lobulated fluid-containing tubular mass which extended anteriorly to posteriorly along the medial orbital wall, nasal to the eyeball. She was followed once a year for 8 years until the age of 49 years when she decided to undergo surgical resection because of the enlarged mass. The lobulated large mass was resected and the pathology showed sparsely distributed spindle cells, positive for CD34, in alcian blue-positive mucous substances, indicative of myxoma. Postoperative magnetic resonance imaging showed residual lobulated tubular mass along the optic nerve on the medial side and superior to the eyeball. The residual orbital mass showed stable structure with more evident connection with the ethmoid sinus lesion, suggestive of the ethmoid origin, in 12 years until the age of 61 years. In the review of 20 patients with orbital myxomas in the literature, in addition to this case, roughly classified locations in the orbit were retrobulbar in 8 patients, on the lateral side of the orbit in 4, on the superior side in 6, on the medial side in 1 (this patient), and in the orbit with no specific description in 2. In pathological examinations, immunohistochemistry was not done in 8 patients, done but all negative in 2, and positive in 11 patients: nerve sheath myxoma was diagnosed in 3 patients based on positive S100 staining. Orbital myxoma is rare but considered in differential diagnosis of orbital masses.

Case Report: Atrial myxoma combined with hyperthyroidism in an adolescent with literature review

The most common primary cardiac tumors in adults are atrial myxomas, with adolescent-onset being uncommon. In this case report, a 15-year-old female was hospitalized with cerebrovascular embolism and later diagnosed with a left atrial myxoma. She had previously shown signs of distal vascular micro thrombosis, including recurring bilateral lower extremity rash, which are crucial for the early diagnosis and differential diagnosis of atrial mucinous neoplasm. We reviewed the various clinical symptoms and diagnostic approaches to identify left atrial mucinous neoplasm. This patient also had a combination of endocrine-related diseases. We reviewed the diagnostic approach for the Carney Complex (CNC) and discussed the role of thyroid disease in diagnosing CNC.

A rare left ventricular cardiac myxoma mimicking fibroma

BACKGROUND

In most cases, it is not difficult to differentiate common left ventricular (LV) cardiac myxomas from fibromas because they are different disease entities and have different imaging findings. Herein, we present a case of a tumor with histological characteristics of a LV cardiac myxoma even though its imaging and macroscopical views were similar to that of fibroma.

CASE PRESENTATION

A 65-year-old woman was admitted to the hospital with chest tightness and palpitations which persisted for 2 years. Transthoracic echocardiogram and transesophageal echocardiography revealed a 23 mm × 8 mm, polyp-like-shaped, homogeneous, firm, solitary, mobile and solitary LV mass, which protruded into the left atrium during systole, resulting in mild mitral regurgitation. LV contrast-enhanced echocardiography revealed that there was little contrast agent filling in the LV mass. To further clarify the nature of the mass, non-enhanced and contrast-enhanced coronary computed tomography (CT) angiograms showed a 19 mm × 8 mm relatively homogeneous low density with punctate calcifications mass and no significant enhancement. Thus, we preoperatively diagnosed her condition as a LV fibroma and performed excision of the tumor under cardiopulmonary by-pass by using port-access approach through right mini-thoracotomy. The postoperative pathological diagnosis of the tumor was in fact a LV myxoma.

CONCLUSIONS

LV cardiac myxomas mimicking fibroma makes diagnosis difficult, and sonographers should be aware of this imaging changes.

Point-of-Care Ultrasound Diagnosis of a Giant Left Atrial Mass

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Cardiac myxomas can cause cardiac, embolic, and/or constitutional symptoms.

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POCUS augments emergency care and assists in clinical decision-making.

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Multimodality imaging can help discern CMs from thrombi and other tumors.

Cardiac myxomas: A narrative review

Cardiac myxomas are common primary neoplasms of the heart. They are biologically benign but “functionally malignant” because of the potential for embolization. They arise most commonly from the left atrium, but no chambers of the heart are immune. They may be sporadic in the majority but also familial as a part of the Carney complex. Two morphological forms exist: polypoid and papillary. Polypoid myxomas often present with obstructive features, while the papillary forms are more prone to embolization. Histogenesis is still controversial; the current view centres around origin from the primitive pluripotent mesenchymal cells. They may be of giant proportion, be calcified or get infected. Clinical presentation typically involves the triad of intracardiac obstruction, embolic events and constitutional symptoms. Precordial examination findings may simulate those of mitral or tricuspid stenosis. The presence of tumour plop and change of the physical findings with changing position may help differentiation between the two. Echocardiography is the investigation of choice. Echogenic polypoid or papillary mobile mass within the atrial cavity remaining attached to the interatrial septum through a stalk are the tell-tale echocardiographic features. Cardiac magnetic resonance and computed tomographic scanning may have incremental diagnostic value. Histopathological examination reveals abundant loose myxoid stroma with scattered round, polygonal or stellate cells with dense irregular nuclei. Genetic testing may detect mutations in the PRKAR1A gene in the familial form of cardiac myxoma, i.e. the Carney complex. Surgical excision is the mainstay of treatment with low operative mortality, excellent postoperative survival and low recurrence rate. The current trend favours minimal-access surgery with or without robotic assistance. Physicians should have appropriate preparedness to make a timely diagnosis and enthusiastic treatment to avoid potentially fatal complications.

Cardiac myxomas: clinical presentation, diagnosis and management

Cardiac myxomas (CM) are the most common type of primary cardiac tumours in adults, which have an approximate incidence of up to 0.2% in some autopsy series. The purpose of this review is to summarise the literature on CM, including clinical presentation, differential diagnosis, work-up including imaging modalities and histopathology, management, and prognosis. CM are benign neoplasms developed from multipotent mesenchyme and usually present as an undifferentiated atrial mass. They are typically pedunculated and attached at the fossa ovalis, on the left side of the atrial septum. Potentially life-threatening, the presence of CM calls for prompt diagnosis and surgical resection. Infrequently asymptomatic, patients with CM exhibit various manifestations, ranging from influenza-like symptoms, heart failure and stroke, to sudden death. Although non-specific, a classic triad for CM involves constitutional, embolic, and obstructive or cardiac symptoms. CM may be purposefully characterised or incidentally diagnosed on an echocardiogram, CT scan or cardiac MRI, all of which can help to differentiate CM from other differentials. Echocardiogram is the first-line imaging technique; however, it is fallible, potentially resulting in uncommonly situated CM being overlooked. The diagnosis of CM can often be established based on clinical, imaging and histopathology features. Definitive diagnosis requires macroscopic and histopathological assessment, including positivity for endothelial cell markers such as CD31 and CD34. Their prognosis is excellent when treated with prompt surgical resection, with postsurgical survival rates analogous to overall survival in the age-matched general population.