A report of mesothelial/monocytic incidental cardiac excrescences and a literature review

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.

Cardiac Excrescences of Unusual Origin

Mesothelial/monocytic incidental cardiac excrescences (cardiac MICE) are a rare finding that are most often discovered incidentally either upon echocardiography or invasive cardiovascular procedures. In total, less than 50 known cases have been reported since first being discovered over 30 years ago. They are typically benign lesions; however, there has been a reported case of cardiac MICE being responsible for severe cardiopulmonary compromise and another case of the lesion embolizing leading to cerebral infarctions and ultimately death. Cardiac papillary fibroelastomas are also uncommon lesions found in the heart though they are not as rare as cardiac MICE. They are also benign and are typically attached to valvular surfaces; however, they also can be found as mobile masses. Just as cardiac MICE, they are capable of causing turbulent flow and thrombus formation and have been reported as the cause of ischemic events due to their ability to embolize. We present a case of cardiac MICE and cardiac papillary fibroelastoma in an individual who initially presented with neurologic symptoms concerning for a cerebrovascular accident. The patient was found to have a left ventricular mass composed of both cardiac MICE and cardiac papillary fibroelastomas.

Nodular histiocytic/mesothelial hyperplasia as consequence of chronic mesothelium irritation by subphrenic abscess

PURPOSE

Pleural nodular histiocytic/mesothelial hyperplasia is a nodular histiocytic/mesothelial proliferation, often delimiting cystic cavities, due to irritation by a pulmonary noxa. Case report results: The patient had right pleural parietal and diaphragmatic thickness, with pleural effusion, without lung alterations. He previously underwent left hemicolectomy and liver resection, due to a diverticulitis and a liver histiocytes-rich abscess. Video-assisted thoracoscopy biopsy showed a double population of reactive mesothelial cells and histiocytes.

CONCLUSION

Nodular histiocytic/mesothelial hyperplasia represents a potential pitfall for pathologists. Immunohistochemistry is crucial for the differential diagnosis with some malignancies. We suggest that in our patient, a chronic mesothelium inflammation happened by transdiaphragmatic involvement as a consequence of the liver abscess. Some pathogenetic mechanisms are hypothesized.

Heterotopic breast epithelial inclusion of the heart: report of a case

We report a case of heterotopic breast epithelial inclusion of the heart incidentally found on a native heart in a 73-year-old man who received orthotopic heart transplantation for ischemic cardiomyopathy. The lesion could not be recognized on gross inspection. Histologic sections from the left anterior atrium to interatrial septum showed focally microcystic ductal/tubular structures lined by a biphasic pattern of cuboidal to columnar apical epithelial cells with an outer layer of flattened basal cells. These glandular structures were arranged in vaguely lobular and focally infiltrative patterns in the epicardium and interstitium. No architectural or cytologic atypia or mitotic or apoptotic figures were seen. The apical epithelial cells were immunoreactive for pankeratin, cytokeratin (CK) 7, estrogen receptor, progesterone receptor, gross cystic disease fluid protein-15, and negative for CK20, calretinin, Wilms' tumor suppressor gene (WT1), CD31, suggestive of mammary epithelial differentiation. The basal cells were immunoreactive for pankeratin, CK7, CK5/6, D2-40, smooth-muscle actin and focally S100, suggestive of myoepithelial differentiation. Although the heterotopic breast tissue on the skin along the milk line is well recognized, it has not been described to involve internal organs including the heart.

Cardiovascular pseudoneoplasms

CONTEXT

Primary cardiac tumors are rare and the great majority are benign neoplasms. Mass-forming reactive and pseudoneoplastic growths are less common, but recognizing and distinguishing these lesions from the neoplasms they resemble is critical to appropriate patient care.

OBJECTIVE

The general clinical, imaging, gross pathologic, and histologic features of 5 important pseudoneoplasms (inflammatory myofibroblastic tumor, hamartoma of mature cardiac myocytes, mesothelial/monocytic cardiac excrescences, calcified amorphous tumor, and lipomatous hypertrophy of the atrial septum) are discussed, with an emphasis on features differentiating them from other benign and malignant tumors.

DATA SOURCES

Pertinent citations of the literature and observations from the authors' experience are drawn upon.

CONCLUSIONS

While lacking malignant potential, these lesions can be associated with considerable morbidity and occasional mortality. Their recognition is important in guiding patient management, providing both guidance for appropriate therapy and avoidance of inappropriately aggressive and toxic treatments.

Mesothelial/monocytic incidental cardiac excrescence

Mesothelial/monocytic incidental cardiac excrescence (MICE) is a very uncommon lesion. Diagnosis is incidental and may simulate thrombotic lesions. One of the hypotheses with regard to the etiology of this lesion is a previous cardiac procedure especially mitral valve repair or commissurotomy. Herein, we describe a MICE incidentally found in a patient who underwent mitral valve replacement, as a thrombotic lesion on the left atrial auricle. Histopathologic examination suggested MICE lesions and immunohistochemical stains confirmed it.

Mesothelial/monocytic incidental cardiac excrescences of the heart: case report and literature review

Mesothelial/monocytic incidental cardiac excrescences (MICE) of the heart are rare benign entities that have only been diagnosed incidentally, following cardiac surgical procedure. To date, totally 35 cases have been reported in the English literature. We describe an additional case of cardiac MICE presenting with severe aortic regurgitation for aortic valve replacement in a 20-year-old Chinese male patient. On microscopic examination, the findings initially were confused with true neoplasm. However, the related gross appearance, clinical history and further immunohistochemical staining enabled an accurate diagnosis. We review the relevant literature and found that immunohistochemical staining, especially the anti-cytokeratin antibody (AE1/AE3) and KP1 (CD-68) that were used by most investigators previously, was significant while making the diagnosis, because the two components of the cells show a contrast immunoreactivity to these two makers. The pathologists should always be alert to this entity while diagnose a cardiac surgery specimen.

A Case of Mesothelial/Monocytic Cardiac Excrescence Causing Severe Acute Cardiopulmonary Failure

Mesothelial/monocytic incidental cardiac excrescence (MICE) is a benign lesion composed of a haphazard mixture of mesothelial cells, histiocytes, and fibrin, often found incidentally during cardiac valve replacement. Its pathogenesis is controversial with some authors favoring an artifactually produced amalgam while others espoused a reactive phenomenon. Clinically, this entity is important because of potential misdiagnoses as malignancies. We report a case in a 65-year-old man with severe acute aortic regurgitation. A 2.0-cm mobile aortic valve vegetation was documented by transesophageal echocardiography prior to any cardiac instrumentation. At surgery, the lesion was immediately visualized together with free-floating vegetation in the left ventricular outflow tract. Routine and immunohistochemical examination showed a nodule composed of predominantly histiocytes and mesothelial cells, together with fibrin and scattered neutrophils. To our knowledge, this is the first reported case of a mesothelial/monocytic cardiac excrescence causing acute cardiopulmonary failure. The literature on MICE is reviewed with discussion of its etiology.

Establishment of permanent cell lines purified from human mesothelioma: morphological aspects, new marker expression and karyotypic analysis

This study reports the establishment of three major subtypes of human mesothelioma cells in tissue culture, i.e. the epithelioid, sarcomatoid and biphasic forms, and compares their phenotypic and biological characteristics. Primary cells isolated from biopsies or pleural exudates were subcultured for over 50 passages. We evaluated immunoreactivity using various mesothelial markers related to histological patterns of these cell lines. For epithelioid cells, calretinin and cytokeratin were found to be useful and easily interpretable markers as for control mesothelial cells. The biphasic form was only partially positive and the sarcomatoid type negative. Vimentin was expressed by all cell lines. BerEP4, a specific marker for adenocarcinoma, was negative. Interestingly, while the macrophage marker CD14 was negative, immunoreactivity for a mature macrophage marker (CD68) was expressed by all cell types, suggesting that this marker might constitute an additional tool useful in the differential diagnosis of mesothelioma. At the ultrastructural level, a cell surface rich in microvilli confirmed their mesothelial origin. PCR analysis revealed that none of the cell lines contained SV40 DNA. Karyotypic analyses showed more complex abnormalities in the epithelioid subtype than in the sarcomatoid form. These cell lines may be useful in the study of cellular, molecular and genetic aspects of the disease.