Molecular genetic diagnosis of the familial myxoma syndrome (Carney complex)

Giant Right Ventricular Mass Protruding into the Pulmonary Artery during Systole

Myxomas are the most common primary cardiac tumors in adults and mainly originate in the left atrium with a slight female predominance. Only 3%–4% of myxomas are detected in the right ventricle. Although these tumors are histologically benign, they can lead to several catastrophic complications such as embolization or obstruction of blood flow at the mitral or tricuspid valve orifices. We report a rare case of right ventricular myxoma presented with near-syncope attacks and worsening dyspnea.

A rare case of right ventricular myxoma causing recurrent stroke

We present a 62-year-old lady admitted in our hospital with two episodes of acute ischemic stroke about 2 weeks apart. She was evaluated for acute ischemic stroke and was thrombolysed for recent stroke in right MCA territory first time. On further evaluation, she was found to have a RVOT mass. A transthoracic and transesophageal echocardiogram revealed a PFO and a large, 5.1 cm × 2.3 cm, ovoid, well circumscribed, echogenic mass in the right ventricle outflow tract attached by small pedicle to the ventricular side of anterior tricuspid leaflet, partly obstructing the right ventricular outflow tract and protruding through the pulmonic valve during systole. She was scheduled for surgery (right ventricular mass excision and PFO closure) after 3 weeks due to the risk of secondary hemorrhage in the infarcted area following thrombolysis and anticoagulation and so was discharged with medications after full neurologic recovery after about a week of hospital stay.

She was readmitted 7 days after discharge, before the scheduled date of surgery with history of weakness of right upper limb, slurred speech and mild breathing difficulty lasting for about 20 min following which she improved slowly (transient ischemic attack). The tumor was completely removed with the stalk using cardiopulmonary bypass support. The histopathological findings confirmed the diagnosis of myxoma.

[Carney complex. Clinical, pathological and genetic features in two generations of a family]

Clinical symptoms of Carney complex occurred in two female members of one family (mother and daughter). In addition to the clinical symptoms, we describe the pathological findings in the adrenals (pigmented nodular hyperplasia of the adrenal cortex), heart (myxoma) and skin/soft tissues (superficial angiomyxomas). Genetic investigation revealed a mutation on the long arm of chromosome 17 in both patients; this mutation had previously been described only in Carney complex type 1. Unilateral adrenalectomy was performed in both these cases, 13 years ago and 7 months ago, respectively. Lifelong cardiac surveillance is mandatory to prevent death from embolism or arrhythmia.

A huge obstructive myxoma located in the right heart without causing any symptom

Cardiac myxoma is unusual and mostly located in left atrium. Although it is a benign tumor of the heart, it may cause life-threatening cardiac problems like valvular obstruction, systemic or pulmonary massive embolism, infection, arrhythmia, malignance. We report a huge cardiac myxoma originated from right atrium. It was moving between right atrium and ventricle without any symptoms.

Dorsal dumb-bell melanotic schwannoma operated on by posterior and anterior approach: case report and a review of the literature

The schwannomas are benign tumors originating from Schwann cells which constitute the nerve sheath. The dorsal pigmented type of schwannomas is relatively rare (Goldstein in Am J Med Genet 86:62-65, 2004; Kurtkaya-Yapicier in Histol Histopathol 18(3):925-934, 2003). There are two distinct types of melanotic schwannoma: the sporadic melanotic schwannomas and the psammomatous melanotic schwannomas of Carney complex. We report a case of a patient harboring a right dorsal dumb-bell melanotic schwannoma and left adrenal mass. The patient underwent a surgical procedure for en bloc total removal of the mass by a posterior and anterior approach. Histopathological examination revealed the diagnosis of melanotic schwannoma. At present, we have no reliable marker of histopathological malignancy of melanotic schwannoma so the follow-up period ought to continue for a period of more than 5 years. As the total removal of the melanotic neurinomas is mandatory to prevent possible malignant transformation of the tumor recurrence or regrowth, we believe that the posterior and trans-thoracic approach are the most suitable one for the dorsal dumb-bell schwannoma.

Carney complex

We report an illustrated case of a 61-year-old woman with multiple atrial myxomas and cutaneous hyperpigmentation as part of the Carney complex. The case is notable for an unusually late presentation in life and a strong family history of atrial myxomas and sudden death. The importance of regular life-long echocardiographic screening and surveillance in all family members of affected cases is emphasized.

Clinical phenotypes and molecular genetic mechanisms of Carney complex

Carney complex is a familial multiple neoplasia disorder with characteristic features such as cardiac and cutaneous myxomas and spotty pigmentation of the skin. Clinical genetic analyses have shown that Carney complex is transmitted in an autosomal dominant way and can present with a wide array of other tumours, such as psammomatous melanotic schwannoma, testicular Sertoli-cell tumours, and pituitary adenomas. Molecular genetic studies show that mutations in the PRKAR1A gene, encoding the R1alpha regulatory subunit of cyclic-AMP-dependent protein kinase A, are the cause of Carney complex in most patients. Investigation of genetically engineered animal models confirms the role of PRKAR1A as a tumour suppressor and has begun to elaborate mechanisms underlying tumorigenesis in this disorder. Further genetic studies in human beings have highlighted novel variant phenotypes, such as congenital contractures, which are potentially associated with Carney complex, and have identified alternative genetic pathways to cardiac tumorigenesis, including mutation of the MYH8 gene that encodes perinatal myosin.

Myxoma of the small bowel in a 47-year-old woman with a left atrial myxoma

Although atrial myxoma is the most common primary tumor of the heart, the synchronous occurrence of myxomas of the intestine and the heart has not been reported in the English literature. We report a case of a 47-year-old woman who presented with small bowel obstruction by a pedunculated mass that was found to be a myxoma after resection. A left atrial mass was found incidentally by a computed tomographic scan, and a diagnosis of atrial myxoma was confirmed after a second surgery. The cardiac myxoma showed classic histologic features, with tumor cells layered around vascular channels in an abundant myxoid matrix, while the small bowel lesion was less cellular. Immunohistochemical stains yielded identical results in both. No vascular involvement was noted at either site. This case supports the recommendation that a search for a cardiac lesion should be performed when a myxoma is identified at an unusual location.

Cardiocutaneous syndromes and associations

Multiple cardiocutaneous syndromes and associations are described and reviewed with the emphasis on syndromes that are likely first to be recognized by dermatologists, thereby creating awareness of potential significant cardiovascular disease. Multiple lentigines syndrome, the Carney complex, and Marfan syndrome are examples of syndromes with embryologic and genetic overlap between the cardiac and cutaneous systems. An exhaustive, complete listing of every known disorder or syndrome with combined cardiac and cutaneous findings is beyond the scope of this review. However, all the common associations, both acquired and inherited, including connective tissue, autoimmune, infiltrative, and endocrine disorders are discussed. Because of the serious nature of many of the cardiac defects, early recognition of these conditions by dermatologists and appropriate referrals to colleagues is essential; in addition, when appropriate, genetic counseling is recommended for known heritable disorders.

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be familiar with the embryology of the neural crest, specifically the development of melanocytes and the heart with its vessels, leading to shared abnormalities of the two systems; the major syndromes and associations producing both cutaneous changes, especially of the pigment systems, and cardiovascular abnormalities; the role of the dermatologist in recognizing these changes; and the need to be cognizant and alert in helping screen for associated systemic disease.

Tumors and the heart: molecular genetic advances

Recent molecular genetic investigations of primary cardiac tumors (myxomas, lipomas, rhabdomyomas, and fibromas) have provided insight into fundamental mechanisms of cardiac cell growth. Myxomas are the most common adult cardiac tumor, and familial cardiac myxomas are now appreciated to be caused by mutations in the PRKAR1alpha gene that encodes a regulatory subunit of protein kinase A. Cytogenetic studies have targeted candidate chromosomal loci that may be perturbed during cardiac lipoma pathogenesis. Rhabdomyomas, the most common pediatric cardiac neoplasm, are frequently associated with tuberous sclerosis, caused by mutations in the TSC-1 and TSC-2 genes. The study of Gorlin syndrome has shed light on the etiology of cardiac fibromas. This disorder is caused by mutation of the PTC gene, which regulates cell growth, commitment and differentiation. In the future, manipulation of PRKAR1alpha-, TSC-, and PTC-dependent pathways may foster new strategies to regenerate myocardium in the ischemic or myopathic heart.

Mutations in the protein kinase A R1alpha regulatory subunit cause familial cardiac myxomas and Carney complex

Cardiac myxomas are benign mesenchymal tumors that can present as components of the human autosomal dominant disorder Carney complex. Syndromic cardiac myxomas are associated with spotty pigmentation of the skin and endocrinopathy. Our linkage analysis mapped a Carney complex gene defect to chromosome 17q24. We now demonstrate that the PRKAR1alpha gene encoding the R1alpha regulatory subunit of cAMP-dependent protein kinase A (PKA) maps to this chromosome 17q24 locus. Furthermore, we show that PRKAR1alpha frameshift mutations in three unrelated families result in haploinsufficiency of R1alpha and cause Carney complex. We did not detect any truncated R1alpha protein encoded by mutant PRKAR1alpha. Although cardiac tumorigenesis may require a second somatic mutation, DNA and protein analyses of an atrial myxoma resected from a Carney complex patient with a PRKAR1alpha deletion revealed that the myxoma cells retain both the wild-type and the mutant PRKAR1alpha alleles and that wild-type R1alpha protein is stably expressed. However, in this atrial myxoma, we did observe a reversal of the ratio of R1alpha to R2beta regulatory subunit protein, which may contribute to tumorigenesis. Further investigation will elucidate the cell-specific effects of PRKAR1alpha haploinsufficiency on PKA activity and the role of PKA in cardiac growth and differentiation.

Surgery for cardiac myxomas

Myxomas, particularly left-atrial myxomas, are the most common primary tumors of the heart that cardiac surgeons will be called upon to remove. Although some tumors are discovered incidentally during echocardiographic examination, many produce symptoms caused by the release of inflammatory cytokines, obstruction to intracardiac blood flow, and/or embolization. With rare exception, cardiac myxomas are benign, and excision is safe and curative in most patients. In a 38-year experience at the Mayo Clinic, 100 patients have had 106 operations for myxoma, and there has been only 1 perioperative death. During follow-up extending to 25 years, postoperative survival is similar to that of an age- and sex-matched population, and at 20 years postoperatively, 94% of patients were free of recurrent myxomas. Recognition of familial and syndrome myxomas (eg, Carney's complex) is important in guiding surgical approach, planning follow-up, and predicting recurrence of these unusual neoplasms.