Detection of herplex simplex virus-1 and -2 in cardiac myxomas

Abstract

The etiology of sporadic cardiac myxomas remains elusive. The tendency for these lesions to recur following resection, their immunopathological characteristics, along with their histological and molecular profile, may implicate the presence of an infective agent in this type of tumor. In this study, we investigated the presence of herpes simplex virus (HSV) DNA in a cohort of cardiac myxomas in a tertiary referral centre. Twenty-nine formalin-fixed paraffin-embedded (FFPE) sporadic cardiac myxomas were obtained, 17 of which were shown to be informative. These were compared to 19 macroscopically and microscopically normal heart tissue specimens. The detection of HSV-1 and -2 genomic sequences was achieved with the use of a combined nested PCR-Restriction Fragment Length Polymorphism methodology. The presence of HSV-1 and/or -2 DNA was demonstrated in 6 of 17 (35%) informative sporadic cardiac myxomas, whereas no HSV DNA was detected in normal heart tissues (P < 0.01). The existence of HSV-1/2 DNA in sporadic cardiac myxomas, along with its absence from normal heart tissues, reinforces the possibility that HSV infection might be involved in the development of these lesions. Our findings raise the point of anti-HSV medication postsurgically with a potential benefit in reducing the rate of recurrences.

Figure 1

(a) Histological evaluation of representative HSV-positive and HSV-negative cardiac myxoma cases. Hematoxylin-eosin (H&E) staining of myxoma tissue sections revealed sparsely cellular lesions with a characteristic gel-like stroma of acid mucopolysaccharides, containing individual small cells with sparse cytoplasms forming stellate protrusions into the stroma. (i) HSV-negative left atrial myxoma sample (case 1). (ii) HSV-positive right ventricle myxoma sample (case 7) (×200 magnification, H&E staining). (b) Detection of HSV DNA in representative atrial myxoma specimens. M: 100 bp molecular marker (New England Biolabs), 1–13: atrial myxoma samples, cases 1, 2, 4–6, 8–13: HSV-negative samples, cases 3, 7: HSV-positive samples, 14: positive control (blood sample), and 15: negative control (normal heart tissue).

Figure 2

Absence of HSV DNA from normal heart tissues. HSV and IFN-γ PCR in representative cases with normal heart tissues. PCR. M: 100 bp molecular marker (New England Biolabs), 1 and 7: positive control (blood sample), 2–6: normal heart tissues, and 8: negative control (distilled water). IFN-γ was used to assess the quality and quantity of the examined DNA.

Figure 3

HSV typing via RFLP analysis. Electrophoresis of representative nested-PCR products, positive for HSV, digested with MspI. M: 50 bp marker (New England Biolabs), 1: undigested nested-PCR product (142 bp), 2: positive control containing both HSV-1 (98 bp) and HSV-2 (142 bp) genomic sequences, 3-4: cases infected by HSV-1, and 5: case harboring both HSV-1 and -2.

Figure 4

Neural crest embryological remnants in the adult heart and localization of cardiac myxomas. (a) Embryonic heart. Blue stars indicate the localization of neural crest cells from the pharyngeal mesoderm, which migrate through the aortic arch arteries to the outflow tract and the endocardial cushions. (b) Newborn heart. The Fossa ovalis in the adult heart is an embryonic remnant of the foramen ovale, which closes shortly after birth. (c) Adult heart. Red crosses indicate the attachment of HSV particles to cardiac myxomas. Blue stars indicate autonomic nerve fibers. RA: right atrium, RV: right ventricle, LA: left atrium, and LV: left ventricle.