DNA analysis of cardiac myxomas: flow cytometry and image analysis

Cardiac Masses Discovered by Echocardiogram; What to Do Next?

Cardiac tumors are rare conditions, typically diagnosed on autopsy, but with the advancement of imaging techniques they are now encountered more frequently in clinical practice. Echocardiography is often the initial method of investigation for cardiac masses and provides a quick and valuable springboard for their characterization. While some cardiac masses can be readily identified by echocardiography alone, several require incorporation of multiple data points to reach diagnostic certainty. Herein, we will provide an overview of the main clinical, diagnostic, and therapeutic characteristics of cardiac masses within the framework of their location.

Detection of herplex simplex virus-1 and -2 in cardiac myxomas

The etiology of sporadic cardiac myxomas remains elusive. The tendency for these lesions to recur following resection, their immunopathological characteristics, along with their histological and molecular profile, may implicate the presence of an infective agent in this type of tumor. In this study, we investigated the presence of herpes simplex virus (HSV) DNA in a cohort of cardiac myxomas in a tertiary referral centre. Twenty-nine formalin-fixed paraffin-embedded (FFPE) sporadic cardiac myxomas were obtained, 17 of which were shown to be informative. These were compared to 19 macroscopically and microscopically normal heart tissue specimens. The detection of HSV-1 and -2 genomic sequences was achieved with the use of a combined nested PCR-Restriction Fragment Length Polymorphism methodology. The presence of HSV-1 and/or -2 DNA was demonstrated in 6 of 17 (35%) informative sporadic cardiac myxomas, whereas no HSV DNA was detected in normal heart tissues (P < 0.01). The existence of HSV-1/2 DNA in sporadic cardiac myxomas, along with its absence from normal heart tissues, reinforces the possibility that HSV infection might be involved in the development of these lesions. Our findings raise the point of anti-HSV medication postsurgically with a potential benefit in reducing the rate of recurrences.

Atrial myxomas: pathologic types, tumor location, and presenting symptoms

BACKGROUND

Atrial myxoma is the most common cardiac neoplasm. Although not widely reported, two anatomic types have been observed: solid and papillary. We examined whether differences in gross or microscopic appearance and location correlated with symptomatology, specifically congestive heart failure (CHF), neurologic symptoms, and embolic events.

METHODS

We performed a retrospective review of atrial myxomas removed from 1972 to 2002, recording the clinical presentation, diagnostic modality, tumor location, gross, and microscopic features for each patient. Twenty-six patients (16 females and 10 males) had atrial myxomas excised. Two patients (one female and one male) were excluded due to unavailable pathologic slides.

RESULTS

In 24 patients there were 15 solid and 9 papillary tumors. CHF was more prevalent in solid myxomas, while neurologic symptoms and embolic events were more common in papillary tumors. Tumor location further correlated with presenting symptoms. Ninety-two percent of patients presenting with CHF had tumors attached to the atrial septum. Extraseptal myxomas more frequently presented with neurologic (80% vs. 29%) and embolic features (50% vs. 25%). All patients exhibiting clefted tumor surface had a history of embolization. A higher percentage of solid myxomas (93%) showed hemorrhage within the tumor than with papillary (56%).

CONCLUSIONS

CHF was more common with solid myxomas, and neurologic and embolization events were more common in the papillary type. Septal tumor location showed strong association with CHF, while extraseptal location correlated with neurologic events. We speculate that the various gross and microscopic patterns reflect secondary changes within these neoplasms over the course of their natural history.

Clinicopathologic study and DNA analysis of 37 cardiac myxomas: a 28-year experience

PURPOSE

This study was performed to identify morphologic features of cardiac myxomas related to embolism and to provide a better understanding of the biology of these tumors, mainly in relation to their interleukin (IL)-6 expression and DNA content.

PATIENTS AND METHODS

A total of 37 cardiac myxomas were reviewed retrospectively in a clinicopathologic study that included the correlation of echocardiographic and pathologic findings in 25 cases, together with immunohistochemical evaluation of IL-6 expression and flow cytometric DNA analysis of 35 tumors.

RESULTS

There were 24 female patients and 13 male patients. The mean (+/- SD) age was 52 +/- 15 years. Fifty-four percent of patients presented with dyspnea, 51% presented with increased erythrocyte sedimentation rate (ESR), and 27% presented with embolic episodes, which were significantly associated with villous surface tumors. Atrial fibrillation was registered in 19% of patients and was significantly associated with large left atrial myxomas. Echocardiography proved to be a reliable method for preoperative diagnosis and for predicting tumor size and morphology. There was no perioperative mortality or long-term recurrences. The frequency of early surgical complications was associated with a longer mean ischemic time. Seventeen percent of tumors had abnormal DNA content, and 74% of tumors showed immunohistochemical expression of IL-6. Neither of these factors showed a significant association with embolism or constitutional illness.

CONCLUSIONS

Villous surface myxomas are related to embolism, and large left atrial tumors are related to atrial fibrillation. Echocardiography is a reliable method with which to predict tumor size and morphology. Myxoma cells usually express IL-6, and some tumors have abnormal cellular DNA content. Surgical excision of the tumor is a safe and effective treatment.

[Cardiac myxoma. Clinical-pathological correlation]

INTRODUCTION AND OBJECTIVES

Myxomas are the most common type of primary cardiac tumors. The aim of this study was to analyze the clinical forms of presentation of cardiac myxoma, the postoperative evolution, and the possibility of recurrence and tumoral embolism.

PATIENTS AND METHOD

From July 1992 to March 1999, 31 patients with myxoma were studied. Cell cycles (ploidy pattern of the tumoral DNA) were studied in 12 patients to evaluate the risk of recurrence and tumoral embolism.

RESULTS

The most frequent clinical manifestations were constitutional symptoms (74%), dyspnea (45%), and embolism (41%). Smaller-diameter myxomas correlated independently with tumoral embolism (45%). The in-hospital mortality was 3.2%, no deaths were observed during follow-up (mean: 4.8 years). No patients had clinical or echocardiographic signs of tumoral recurrence. Patients with tumoral embolism (n = 8) were compared with patients without embolism (n = 4). Patients who suffered embolism had higher S phase > 7 and/or DNA index > 1.2 (4/4 patients [100%], p= 0.061) than patients without embolism (2/8 patients [25%]). Cytometry of the only recurrent tumor (second operation) revealed a diploid tumor with a significantly more frequent S phase (10%) than in sporadic myxomas (4.27 2.32%, p = 0.039).

CONCLUSIONS

Constitutional symptoms, dyspnea, and tumor embolism were the most frequent clinical manifestations. Clinical and anatomopathologic characteristics and the cell cycle were not significantly related to tumoral embolism, but there was a tendency toward a higher proportion of cells in S phase and a higher DNA index in tumors associated with embolism. The S phase was significantly more frequent in the only case of recurrent myxoma and could be a potential marker of recurrence.

Ras oncogenes and p53 tumor suppressor gene analysis in cardiac myxomas

Although ras oncogenes and p53 tumor suppressor gene mutations are implicated in the development of several human tumors, little is known about their role in the pathogenesis of primary cardiac tumors. Paraffin-embedded tissue from 19 cardiac myxomas were investigated for the presence of ras oncogenes and p53 tumor suppressor gene abnormalities. Immunohistochemical analysis was used to identify the accumulation of p21-ras and p53 proteins. A polymerase chain reaction was used to amplify exons 1 and 2 of the ras genes and exons 5 to 8 of the p53 gene. The PCR products were analyzed by single strand conformation polymorphism analysis and by direct DNA sequencing. Three of 19 myxomas showed strong positive staining for the ras p21 protein. In contrast, nuclear p53 was not detectable in any of the myxomas. Among the ras p21 immunopositive myxomas, 2 were heterozygous for a missense point mutation of the K-ras, Gly 12Asp. Further screening of the remaining myxomas showed no mutation or even silent polymorphism in any exon of the ras and p53. The results suggest that although genetic alterations of ras oncogenes and p53 are uncommon events in cardiac myxomas, ras mutations may be involved in the pathogenesis of a subgroup of this type of tumor.

Calretinin as a marker for cardiac myxoma. Diagnostic and histogenetic considerations

To study the usefulness of calretinin as an immunohistochemistry marker in the diagnosis of cardiac myxoma (CM) and the origin of myxoma cells, we examined 24 CMs and 9 fetal hearts with immunohistochemical methods on formalin-fixed paraffin-embedded tissues. We compared 24 CMs with 10 mural thrombi, 6 jaw myxomas, and 2 papillary fibroelastomas. Calretinin expression was identified in 100% of CMs and was negative in all cases of mural thrombi, jaw myxoma, and papillary fibroelastoma. Calretinin expression by the neoplastic cells in CM was strong and diffuse and had a cytoplasmic and a nuclear pattern. Calretinin expression in fetal hearts was found in autonomic ganglia cells in the subepicardial tissue of the atria and atrial appendages, along the interatrial and atrioventricular sulci, and in the atrial septum. Results clearly indicate that calretinin can be used as a marker for the diagnosis of CM and that it is a powerful tool for the differential diagnosis, most importantly with mural myxoid thrombi. Furthermore, the positive expression of calretinin by the autonomic neurons in the fetal heart and CM supports the concept that myxoma cells may originate from endocardial sensory nerve tissue.

Phenotypic characterization of cellular components of cardiac myxoma: a light microscopy and immunohistochemistry study

Cardiac myxoma is the most common primary tumor of the heart. A detailed evaluation of cell types in 41 cardiac myxomas by light microscopy and in 30 cases by immunohistochemistry was made. Reactivity to the various antisera were observed in the surface lining cells, the stromal myxoma cells and the cells in the perivascular location. Factor VIII-related antigen (FVIIIR-Ag) and Ulex europaeus agglutinin (UEA-1), both endothelial markers, were positive in 23 cases each. UEA-1 was found to be a more sensitive marker than factor VIII. Desmin and myoglobin were positive in 16 and 24 cases, respectively. Reactivity for cytokeratin was noted in ten cases, one of which showed glandular differentiation. Vimentin and S-100 positivity was obtained in 16 and 14 cases respectively. Thus, cardiac myxoma appears to arise from multipotent cells which have the potential to differentiate along several mesenchymal cells or epithelial cells and may also concurrently exhibit reactivity for both mesenchymal and epithelial markers.

Ovarian myxoma: ultrastructural and immunohistochemical findings

The ultrastructural and immunohistochemical findings are reported in two ovarian myxomas, one of which was also associated with a sclerosing stromal tumor of the same ovary. Both neoplasms showed a myxoid, moderately cellular proliferation of spindle and stellate cells interspersed with areas of fibrosis and hemorrhage as well as delicate vascular spaces. Ultrastructurally, stellate neoplastic cells with irregular nuclei and occasional nucleoli were embedded in a mucinous and loose collagen matrix. Their cytoplasm showed abundant intracytoplasmic thin filaments that rarely condensed into poorly formed dense bodies. These thin filaments correlated with immunoreactivity for muscle-specific actin and vimentin. The neoplastic cells showed no immunoreactivity with antibodies to desmin, S-100 protein, cytokeratin AE1:AE3, factor VIII-related protein, or placental alkaline phosphatase. These ultrastructural and immunohistochemical findings are consistent with myofibroblastic differentiation. These ancillary studies exclude important, clinically more aggressive differential considerations such as myxoid rhabdomyosarcoma, myxoid liposarcoma, myxoid neural tumors, mucinous adenocarcinoma showing pseudomyxomatous change, and myxoid-appearing endodermal sinus (yolk sac) tumor.