Cardiac myxoma cells exhibit embryonic endocardial stem cell features.

The origin of myxoma, the most frequent tumour of the heart, remains uncertain. Previous phenotypic characterizations have shown heterogeneous results and the most recent hypothesis suggests that cardiac myxoma originates from a primitive pluripotential cardiogenic cell. We investigated the expression of actin isoforms in 30 left atrial myxomas by immunohistochemistry and in eight consecutive tumours by RT-PCR. alpha-Smooth muscle actin (alpha-SMA) protein and/or transcripts were detected in all cases, whereas alpha-cardiac actin was observed in few cases and alpha-skeletal actin was always absent. Besides classical features, vessel-like structures were characterized by cells expressing CD34 and, less frequently, alpha-SMA. Confocal microscopy showed focal co-expression of CD34 and alpha-SMA in myxoma cells, suggesting a gradual loss of stem endothelial markers and the acquisition of myocytic antigens. In order to confirm this hypothesis, early cardiac differentiation markers were also investigated. RT-PCR documented the presence of transcripts for Sox9 (100%), Notch1 (87.5%), NFATc1 (37.5%), Smad6, metalloproteinases 1 and 2 alone or in variable combinations and the absence of ErbB3 and WT1. Myxoma cells maintained phenotypic heterogeneity in vitro, including the expression of alpha-SMA and the presence of stress fibres. These findings document in cardiac myxoma cells phenotypic markers of the embryonic endothelial-to-mesenchymal transformation that precedes terminal differentiation of endocardial cushions, supporting the hypothesis that cardiac myxoma cells may derive from adult developmental remnants.

[Cardiac tumors]. / I tumori cardiaci.

Primary cardiac tumors are rare and their subdivision often difficult because of their unknown origin. In the most recent classification, cardiac tumors are divided into benign (about 75% and malignant neoplasms in relationship to their tissue differentiation (rhabdomyoma, haemangioma, etc.) or uncertain aetiology (myxoma, papillary fibroelastoma). Primary malignant tumors are maimly represented by sarcomas. The most frequent tumor is cardiac myxoma, which by itself represents about 50% of all primary cardiac neoplasms. Although non-invasive technologies as trans-esophageal ecocardiography allow the detection and exact localization of cardiac mass, clinical diagnosis is often tardive. This is due, besides the intrinsic rarity, to two main factors: first, the tumor is often asymptomatic (incidental autopic finding) or; alternatively, it may show aspecif symptoms mimicking heart failure or other pathologies. In this article, clinicopathological features of main primary cardiac tumors are presented. Investigation of the histogenesis of some of these neoplasms is still a primary field of research.

Unusual cardiac tumour with perivascular myoid differentiation: a case report.

A previously healthy 70 year old woman was admitted for fatigue and dyspnoea on exertion and cough. A two dimensional echocardiography revealed a mass in the right atrium, which obstructed filling and infiltrated the cardiac chamber wall. Postsurgical histological examination revealed an unusual tumour with prevalent myoid glomangiopericytoma-type and haemangiopericytoma-like patterns. Mitosis and necrosis were absent. A computed tomography scan excluded the presence of metastasis to distant organs or, conversely, metastatic involvement of the heart. Therefore, a diagnosis of tumour with perivascular myoid differentiation was made. This new entity, recently described in soft tissues, can easily recur. Its recognition helps to differentiate from metastasis and other primitive cardiac tumours sharing some morphological features but a different clinical behaviour, with consequent improvement to the management of patient care.

Cellular retinol-binding protein-1 expression in endometrial stromal cells: physiopathological and diagnostic implications.

AIMS: Cellular retinol-binding protein-1 (CRBP-1) contributes to the maintenance of the differentiated state of the endometrium through retinol bioavailability regulation. The aim was to analyse CRBP-1 expression in endometrial stromal cells at eutopic and ectopic sites in different physiopathological conditions. METHODS AND RESULTS: Antibodies to CRBP-1, CD10 and alpha-smooth muscle actin were applied to proliferative (n = 10), secretory (n = 9) and atrophic (n = 7) endometrium, decidua (n = 4), adenomyosis (n = 5), endometriosis (n = 10), endometrial polyps (n = 9), simple endometrial hyperplasia (n = 6), well-differentiated endometrioid carcinoma (n = 6) and submucosal leiomyomas (n = 5). In some cases, Western blotting and reverse transcription-polymerase chain reaction were also applied. CRBP-1 was expressed by eutopic and ectopic endometrial stromal cells more markedly during the late secretory phase and in decidua of pregnancy. CRBP-1 expression was low in the stroma of atrophic endometrium and absent in myometrium, leiomyomas and cervical stroma. CD10 immunoreactivity was weak in atrophic endometrium and in decidua. CONCLUSIONS: CRBP-1 expression characterizes endometrial stromal cells at eutopic and ectopic sites and appears to be more specific than CD10. The level of CRBP-1 varies in intensity according to hormonal variations, reaching its maximum in predecidua and decidua. Thus, immunodetection of CRBP-1 may help to elucidate the physiopathological changes which occur in endometrial stroma and can also be applied as an adjuvant stromal marker.