MUC1, MUC2 and MUC5AC expressions in cardiac myxoma

Abstract

Cardiac myxoma, the most common primary tumor of the heart, has a variable clinical presentation and immunohistochemical profile. An abundant mucopolysaccharidic matrix exists, including mucin, within cardiac myxoma. This investigation first reports the expressions of mucin genes in cardiac myxoma. A retrospective study was conducted between December 1976 and February 2003, comprising 101 consecutive patients with cardiac myxoma who were treated with surgical excision. Detailed clinical parameters also were reviewed. Mucin genes, namely MUC1, MUC2 and MUC5AC, were studied immunohistochemically in 47 randomly selected patients. The study group contained 57 (57%) women and 44 (43%) men, with a mean age of 38+/-21 years. Their presentations included: asymptomatic (41%), dyspnea (35%), stroke (23%), chest pain (7%), fever (6%), syncope (5%) and tricuspid regurgitation (70%). The sample included 90 myxoma located in the left atrium, 3 (3%) recurrent myxoma and 8 (8%) myxoma not located in the left atrium. The myxoma did not differ with location or clinical event in terms of pathological scores, such as vascular proliferation, inflammation, cellularity, hyaline, calcification and thrombosis. Cardiac myxoma is characterized by excessive mucus secretion. Expression of membrane-associated MUC1 was considerably higher than that of the secreted mucins, MUC2 and MUC5AC (P<0.05). Furthermore, expression of MUC5AC is related to lesser embolism (P<0.05). This work first examined the immunohistochemical expression of mucin (MUC1, MUC2 and MUC5AC) in cardiac myxoma. This investigation then showed that the expression of representative membrane-associated mucin, MUC1, and/or secretory mucins, MUC2 and MUC5AC, in cardiac myxoma was associated with important tumor clinicopathological characteristics. Moreover, MUC5AC appears related to lesser embolism. This approach can help distinguish the potential roles of secretory mucins versus membrane-associated mucins in the development of cardiac myxoma.