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Cardiac myxomas are rare tumors with a heterogeneous cell population including properly neoplastic (lepidic), endothelial and smooth muscle cells. The assessment of neoplastic (lepidic) cell differentiation pattern is rather difficult using conventional light microscopy immunohistochemistry and/or whole tissue extracts for mRNA analyses. In a preliminary study, we investigated 20 formalin-fixed and paraffin-embedded cardiac myxomas by means of conventional immunohistochemistry; in 10/20 cases, cell differentiation was also analyzed by real-time RT-PCR after laser capture microdissection of the neoplastic cells, whereas calretinin and endothelial antigen CD31 immunoreactivity was localized in 4/10 cases by double immunofluorescence confocal microscopy. Gene expression analyses of α-smooth muscle actin, endothelial CD31 antigen, alpha-cardiac actin, matrix metalloprotease-2 (MMP2) and tissue inhibitor of matrix metalloprotease-1 (TIMP1) was performed on cDNA obtained from either microdissected neoplastic cells or whole tumor sections. We found very little or absent CD31 and α-Smooth Muscle Actin expression in the microdissected cells as compared to the whole tumors, whereas TIMP1 and MMP2 genes were highly expressed in both ones, greater levels being found in patients with embolic phenomena. α-Cardiac Actin was not detected. Confocal microscopy disclosed two different signals corresponding to calretinin-positive myxoma cells and to endothelial CD31-positive cells, respectively. In conclusion, the neoplastic (lepidic) cells showed a distinct gene expression pattern and no consistent overlapping with endothelial and smooth muscle cells or cardiac myocytes; the expression of TIMP1 and MMP2 might be related to clinical presentation; larger series studies using also systematic transcriptome analysis might be useful to confirm the present results.

Objectives: To evaluate the role of histology in diagnosis and management of biologically benign heart tumors causing life-threatening symptoms and even death in children and fetuses. The clinical impact of a multidisciplinary approach including 2-D echocardiography, histology, genetics, and cardiac surgery has not yet been fully elucidated., Study Design: Forty-one consecutive antenatal (n = 17) or postnatal (n = 24) detected cardiac masses were evaluated by 2-D echocardiography (in alive patients) or at autopsy, and 12/41 cases with definite histologic diagnosis of primary and benign cardiac tumor were entered in this study., Results: Rhabdomyomas (n = 6), hemangiomas (n = 3), central fibrous body chondroma (n = 1), fibroma (n = 1), or left atrial myxoma (n = 1) were histologically diagnosed in 4 fetuses and in 8 children. Death occurred in 6 patients showing diffuse or infiltrative tumors, 2/6 experiencing intrauterine death or sudden and unexpected infant death. Seven patients underwent surgery, 4/7 are alive and well at >5 years follow-up, whereas 3 deaths followed partial tumor resection. Two fetuses with extensive tumor/s were aborted. Tuberous sclerosis complex gene mutations were seen in patients with rhabdomyomas., Conclusions: Histology represents the best diagnostic approach in life-threatening pediatric cardiac tumors allowing definite diagnosis in cases other than rhabdomyoma and in sudden deaths, influencing clinical management and counselling. 2-D echocardiography remains the main tool for early clinical diagnosis and follow-up. A multidisciplinary approach is advisable because of rarity, difficult management, and possible associations with inheritable diseases., (Copyright © 2013 Mosby, Inc. All rights reserved.)

We report a case of left atrial cardiac myxoma harbouring an incidental atypical B-cell lymphoid proliferation. Histology disclosed classic myxoma cells embedded in a mucopolysaccharide-rich matrix and a micronodular atypical lymphoid proliferation under the surface of the mass. Myxoma cells were immunoreactive for calretinin, while lymphoid cells expressed B lineage markers (CD 20+, CD79a), without evidence of clonality. Moreover, they were LMP1 positive; EBNA2 negative; KSHV/HHV8 negative; and, by in situ hybridization, EBER/Epstein-Barr virus (EBV) positive and Kappa and Lambda negative. According to the 2008 WHO schemes, the present case shares close similarities either with diffuse large B-cell lymphomas growing in the context of long-standing chronic inflammation or with primary effusion lymphomas, solid variant, both associated with EBV infection. This is the sixth case of incidental atypical lymphoid proliferation discovered in a cardiac myxoma reported so far. The optimal treatment of such lesions remains undefined, but their clinical course is indolent. After an accurate staging workup, without any postsurgical treatment, the patient we observed has been well with no recurrence of the disease at 6 years of follow-up., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Glandular cardiac myxomas are very rare tumors of uncertain histogenesis that display glandular structures within otherwise typical myxomatous tissue. The origin of the glands has been attributed to epithelial differentiation of a totipotent cardiomyogenic precursor cell or to entrapped embryonal rests in the tumor. We studied four cases of glandular myxomas (three sporadic and one familial) to define the immunophenotypic profile of the glandular elements. The glands were either single and located within the myxoma cell islands (three cases) or in groups embedded in the myxomatous matrix. In the latter case, the glands featured villous projections, irregular profile, active inflammation or focal reactive cellular atypia (case 3) and had acidic and neutral mucins (mostly sialomucins). The cytokeratin expression profile (cytokeratin 7 and 20 co-expression) was similar to that of foregut derivatives. Scattered chromogranin-positive neuroendocrine cells were observed in case 3. Our findings indicate that the glandular component in cardiac myxoma is morphologically heterogeneous. In some cases, the scattered glands may derive from a divergent (epithelial) differentiation of myxoma cells; in others, entrapment of embryonic gastrointestinal rests (with mature neuroendocrine and mucous cell populations) could be the case.

We report a rare case of complete embolization of a left atrial myxoma resulting in total occlusion of the suprarenal abdominal aorta. A 54-year-old man was admitted to hospital because of acute thoracic pain with paraplegia and acute renal failure. Abdominal computed tomography and angiography showed evidence of total occlusion of the suprarenal aorta. Intraoperatively, the aorta was found to be occluded by a hard neoformation, histologically defined as atrial myxoma. A diagnosis of atrial myxoma should be suspected in young patients suffering from acute thoracic pain and affected by paraplegia and acute renal failure. Early diagnosis may significantly abate the morbidity and mortality rates associated with this condition.