Myxoma, Intracardiac

A number sign (#) is used with this entry because in some instances intracardiac myxoma is a solitary manifestation of heterozygous mutation in the PRKAR1A gene on chromosome 17q24.

Atrial myxoma is a component of the Carney complex (160980), which is also caused by mutation in the PRKAR1A gene.

Clinical Features

Krause et al. (1971) treated a 34-year-old patient with a pulmonic valve myxoma complicated by bacterial endocarditis. A brother of the patient had died at age 25 years of left atrial myxoma. Two other sibs had had rheumatic heart disease.

Heydorn et al. (1973) reported the occurrence of atrial myxoma in 2 teenaged brothers. Kleid et al. (1973) described left atrial myxoma in a 14-year-old boy and a right atrial myxoma in his 16-year-old brother. Farah (1975) reported affected brother and sister. Siltanen et al. (1976) reported myxoma in a mother and all 3 of her sons.

Powers et al. (1979) described myxoma in father and daughter. The daughter had an infected right ventricular myxoma that was mistaken for valvular bacterial endocarditis. The father had a right atrial myxoma associated with atrial septal defect and mitral valve prolapse, and findings suggestive of paradoxical emboli. Grauer and Grauer (1983) reported affected father and daughter.

Farah (1994) used 2-dimensional echocardiography to study relatives of 14 patients with cardiac myxoma. Four family members from 2 different families were found to have cardiac myxoma. The first family included a brother and a sister, both with acromegaly, suggesting a syndromal form of myxoma. Farah (1994) stated that 'none of the family members had skin tumors, abnormal pigmentation, other tumors or evidence of endocrine disease.' In the family in which a brother and sister had atrial myxoma and acromegaly, he also stated that 'a complete study of all members of this family was not possible because some members refused the echocardiographic studies provided free.' It should be noted that the association of acromegaly with familial myxoma was reported by Carney et al. (1985). Thus, it seems likely that the sibs in fact had Carney syndrome. Indeed, the sister would appear to have been case 14 of Carney et al. (1985). In that report, the brother was in fact said to have pigmented spots of the face and lips and had had nodular and pedunculated myxomas of the skin removed. The mother and 3 out of 7 children had cardiac myxoma. Farah (1994) concluded that cardiac myxoma was more frequently found in family members when the proband had right-sided or bilateral myxoma; that patients with familial cardiac myxoma are younger than the nonfamilial cases; and that long-term recurrence is more frequent. Cardiac myxomas of Carney complex are histologically indistinguishable from more common sporadic cardiac myxomas and, like the latter, most often arise in the left atrium at the fossa ovalis (Carney, 1985). However, unlike sporadic cardiac myxomas, which most often occur as isolated single lesions in middle-aged women and which are usually amenable to surgical resection, syndromic cardiac myxomas exhibit no age or sex preference and may present as multiple concurrent lesions in any cardiac chamber. Affected individuals may have multiple recurrences at any cardiac location despite adequate surgical margins.

In a review of the literature, van Gelder et al. (1992) noted 15 families with myxoma of the heart, to which they added 2 more. The patients were young (mean age 27 years) with multicenteric lesions in 22% of the cases. In 61%, the tumors occurred in the left atrium, with a recurrence rate of 10% after removal.

Dandolu et al. (1995) described a family in which the mother had biatrial myxoma with stalks growing from either side of the interatrial septum. A son and a daughter of hers had atrial myxoma and a 12-year-old son had died suddenly after having cardiac symptoms consistent with myxoma. No signs indicative of Carney syndrome were found. Dandolu et al. (1995) suggested autosomal dominant inheritance.

Inheritance

From a review of the literature, van Gelder et al. (1992) concluded that the mode of inheritance of myxoma of the heart appears to be autosomal dominant.

Molecular Genetics

Liebler et al. (1976) described a family in which 4 sibs had intracardiac myxomas. Kirschner et al. (2000), who stated that this family had no other manifestations of the Carney myxoma-endocrine complex (160980), demonstrated a specific mutation in the PRKAR1A gene (188830.0004).