Giant Mitral Valve Rhabdomyoma Resection in a Pediatric Patient

The incidence of primary cardiac tumors is extremely rare in pediatric population, ranging from 0.027% to 0.08% in autopsies. The majority of these tumors are benign, being the rhabdomyoma, the most prevalent histologic type (1). Rhabdomyomas are generally multiple, can affect both ventricles indistinctly, and could have a spontaneous regression in smaller lesions. Management of these tumors can vary according to growth and the age of diagnosis. The mitral location of this type of tumor is unusual and the strategy of treatment can vary according to size and symptoms (2-6). The authors report a case of the surgical resection of a giant mitral rhabdomyoma in a pediatric patient.

An 8-year-old girl weighing 20 kg was referred to the authors’ institution with progressive shortness of breath and fatigue. A transthoracic and transesophageal echocardiogram revealed a 9 mm x 12 mm tumor in the anterior and posterior leaflet of the mitral valve with moderate to severe mitral regurgitation. Cardiac magnetic resonance revealed a sessile and vascularized anterior and posterior mitral valve tumor measuring 10 x 13 mm. After discussion among team members and deterioration of clinical condition, surgical resection was decided.

Through a median sternotomy, cardiopulmonary bypass was instituted. After cardioplegic arrest, the left atrium was opened revealing a yellowish white lobulated giant cardiac tumor that compromised the totally of both the anterior and posterior mitral leaflets, with extension to the posteromedial papillary muscle precluding resection without valve damage. Therefore, mitral valve replacement was performed with a 25 mm mechanical mitral valve after tumor excision (Carbomedics Optiform, Sorin Group, Italy).

The postoperative course was uneventful and the patient was discharged after seven days. Macroscopic pathological examination revealed a smooth, lobulated, elastic, and yellowish white tumor measuring 5 x 3 x 1.5 cm. Microscopic examination demonstrated collagen fibrosis and benign mesenquimal neoplasia proliferation. The immunohistochemistry evidenced myoglobin and S100 positive compatible with mitral valve rhabdomyoma.

The authors present this case to report an unusual localization of the most frequent cardiac tumor in the pediatric population. Although different reports show the possibility of regression over the years, this could not happen and the patient could develop symptoms of heart failure. It is important to highlight that the possibility of clinical surveillance versus surgical resection, either partial or complete, could be limited to tumor size, location, and age of diagnosis.

References

1. Tzani A, Doulamis IP, Mylonas KS, Avgerinos D V., Nasioudis D. Cardiac tumors in pediatric patients: a systematic review. World J Pediatr Congenit Heart Surg. 2017; 8: 624–632.
2. Linnemeier L, Benneyworth BD, Turrentine M, Rodefeld M, Brown J. Pediatric cardiac tumors: a 45-year, single-institution review. World J Pediatr Congenit Heart Surg. 2015; 6:215–219.
3. Wang Y, Wang X, Xiao Y. Surgical treatment of primary cardiac valve tumor: Early and late results in eight patients. J Cardiothorac Surg. 2016; 11:1–7.
4. Pillai R, Kharma N, Brom G, Becker AE. Mitral valve origin of pedunculated rhabdomyomas causing subaortic stenosis. Am J Cardiol. 1991; 67: 663–664.
5. Atik E. Late involution of obstructive rhabdomyoma of the mitral valve. Arq Bras Cardiol. 2009 Jul;93(1):e14.
6. Seki H, Bakhtiary F, Vollroth M, Mohr FW, Kostelka M. Rescue surgery for neonate with huge rhabdomyoma and left outflow obstruction. Asian Cardiovasc Thorac Ann. 2016;24: 875–877.

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