Case report:
A 15-month-old girl was admitted to the hospital with a chief complaint of pulmonary artery stenosis found during the foetal period and cardiac murmur found after birth. Her vital parameters were normal; there was no cyanosis, and oxygen saturation (SpO2) was 98% in room air. There was no history of trauma or infection.
Initial examination revealed a systolic murmur at the left sternal edge and clear lung fields, with no lower limb oedema. Transthoracic echocardiography showed a 9.6 mm x 9.2 mm nearly circular abnormal cystic mass in the main pulmonary artery adherent to the pulmonary valve (Figure 1(a)). The pulmonary valve appeared thickened and restricted, with a peak gradient of 61 mmHg, consistent with valvular pulmonary stenosis. Transthoracic echocardiogram examination also revealed a secundum-type atrial septal defect (ASD) with a diameter measuring 21 mm. In addition, the patient had right heart enlargement and mild tricuspid regurgitation.
The mass was excised through a right thoracotomy under cardiopulmonary bypass. The pulmonary valve orifice was not narrowed, the left anterior valve was lengthy, and the right anterior valve was slightly stiff. The tumour was a sessile cyst with a diameter of 1 cm. It was attached to the left posterior valve and prolapsed into the pulmonary artery. The impression of the surgeon was that the tumour originated from the pulmonary valve, and he could find a clear cleavage (Figure 1(b)). The tumour was completely resected macroscopically. The atrial septal defect was closed by a Gore-Tex patch.
Histological examination of the lesion confirmed the diagnosis of lipoblastoma. Lobules of mature as well as immature fat cells, signet-ring cells, and multivacuolated cells of varying degrees of differentiation can be seen under the microscope. In contrast to myxoid liposarcoma which concentrated peripherally, mature fat cells are concentrated in the central portion of the lobule (Figure 2(a)). Immunohistochemical results showed positive immunostaining for CD34 and S-100 (Figure 2(b)).
The postoperative period was uneventful, and the patient was asymptomatic thereafter. When seen 2 months later, echocardiogram showed no pulmonary valvular incompetence. On further follow-up, there was no recurrence.