Cardiac rhabdomyoma: an uncommon culprit in sudden infant death

Abstract

Sudden death in infants remains a common and poorly understood cause of childhood mortality in the USA. Pediatric cardiac tumors, although rare, may underlie some cases of unexplained sudden infant death. Autopsy is a crucial diagnostic step in these cases, as both gross and microscopic examination of the heart may uncover occult cardiac tumors. Rhabdomyomas are the most common cardiac tumors in childhood and may result in arrythmia and sudden death. We present a case of sudden death in a healthy 5-month-old infant which initially appeared "SIDS-like" until thorough histological analysis revealed an underlying cardiac rhabdomyoma. The case is of particular importance in that the gross examination of the heart was considered completely normal, and the tumor only involved certain portions of the heart microscopically. Had a single random section of myocardium been the only heart section examined microscopically, the diagnosis might have been missed. This case emphasizes the importance of thorough microscopic examination in infant cases, especially in cases where the heart appears grossly normal.

Keywords: Cardiac tumors; Death; Forensic pathology; Infant; Rhabdomyoma.

Fig. 1

Heart (32 g), unfixed A anterior view, B posterior view

Fig. 2

A and B Ventricular cross sections of formalin-fixed heart, showing absence of abnormality (left ventricle: 0.4 cm, interventricular septum 0.6 cm, right ventricle 0.15 cm)

Fig. 3

Left ventricle H&E A 10× magnification, B 40× magnification, C 100× magnification, D normal myocardium next to tumor (right) at 200× magnification

Fig. 4

Immunoperoxidase staining: A negative S100 staining in normal myocardium and tumor (right) at 100 × magnification, B positive myoglobin staining of tumor (right) and normal tissue (200×), C positive myogenin immunoperoxidase staining in tumor (left) and normal tissue (200×)