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\begin{document}

\title{Cardiac lipoblastoma of the pulmonary valve: A rare tumour in an unusual
location}



\author[1]{Feng Tong}%
\author[1]{Zhangke Guo}%
\author[2]{Song Bai}%
\affil[1]{Beijing Children’s Hospital affiliated to Capital Medical University; National Center for Children's Health，China}%
\affil[2]{Beijing Children's Hospital}%


\vspace{-1em}



  
  \date{June 14, 2024}


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\selectlanguage{english}
\begin{abstract}
Lipoblastoma is a rare, benign, fatty tissue tumour that occurs in
infancy and early childhood. Intrathoracic and mediastinal involvement
of this tumour is rare, and an intracardiac location is even rarer. In
this study, we report the case of a 15-month-old girl who presented with
a tumour in the pulmonary valve. A complete resection of the tumour was
undertaken, with a histopathology report confirming the diagnosis of
lipoblastoma.%
\end{abstract}%



\sloppy


\textbf{Cardiac lipoblastoma of the pulmonary valve: A rare tumour in an
unusual location}

Tong Feng, Guo Zhangke, Bai Song

Department of Cardiac surgery, Beijing Children's Hospital affiliated to
Capital Medical University

National Center for Children's Health,China

Beijing 100045,China

56 South Lishi Road, Xicheng District, Beijing

Corresponding author: Guo Zhangke, Email:
\emph{gzkbjetyy@163.com}Telephone: +86 010 69616783

\textbf{Abstract:}Lipoblastoma is a rare, benign, fatty tissue tumour
that occurs in infancy and early childhood. Intrathoracic and
mediastinal involvement of this tumour is rare, and an intracardiac
location is even rarer. In this study, we report the case of a
15-month-old girl who presented with a tumour in the pulmonary valve. A
complete resection of the tumour was undertaken, with a histopathology
report confirming the diagnosis of lipoblastoma.

\textbf{Key words:} lipoblastoma, pulmonary valve, child

\textbf{Introduction:}

Lipoblastoma is a rare benign neoplasm of the foetal embryonal white
fatty tissue occurring most commonly in infants and young children. It
frequently occurs in the subcutaneous tissues of the extremities and the
trunk\textsuperscript{{[}1{]}}. It can also arise in the abdomen, chest,
mediastinum, retroperitoneum, and so on. Primary cardiac lipoblastomas
are very rare tumours, and involvement of the pulmonary valve is
extremely rare. To our knowledge, this is the first report of such a
localization of this type of tumour\textsuperscript{{[}2,3{]}}.

\textbf{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 (SpO\textsubscript{2}) 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.

\textbf{Discussion:}

Primary cardiac tumours in childhood have a very low incidence, although
in recent years, the incidence has increased because of improvements in
heart imaging techniques\textsuperscript{{[}3{]} {[}4{]}}. Most primary
cardiac tumours are benign in the sense they are not invasive. However,
benign tumours maintain the potential for serious illness related to
significant haemodynamic compromise or life-threatening dysrhythmias. In
most cases, the first clinical manifestation depends on the tumour
location and size. In our case, the mass was not very large in size, and
the patient was symptomatic with the persistence of a heart murmur.

Due to the association of lipoblastoma with other heart malformations,
preoperative diagnosis remains challenging. Transthoracic
echocardiography has high sensitivity for the detection of cardiac
masses. It can often provide precise information about the tumour size,
location, shape, mobility, and associated features. It is usually the
first-line investigation. Cardiac MRI is especially advantageous in
defining tissue characteristics and, through the use of gadolinium-based
contrast agents, in differentiating between cardiac masses such as
tumours, which display variable enhancement, and thrombi, which do not
enhance at all\textsuperscript{{[}5{]}}. Before the operation, this
patient was considered to be diagnosed with congenital valvular stenosis
and ASD, therefore, no MRI was applied. The diagnosis of lipoblastoma is
often made postoperatively. It demonstrated adipocytes in different
stages of maturation without anaplasia. The main histological features
of the tumour were multinodular and myxoid foci. Chromosomal
abnormalities have been reported in lipomatous tumours. In our case, we
did not perform any genetic study because the histopathological
evaluation alone was definitive.

Tumours on the heart valve are more likely to cause haemodynamic
disturbances. Complete resection yields an excellent
prognosis\textsuperscript{{[}4,6{]}}. Occasionally, the resection of
adjacent structures is necessary to achieve complete extirpation;
however, in our patient, the resection of the adherent pulmonary valve
was not required. The resection of the tumour and its adjacent tissue
may damage the heart structure; therefore, it is important to carefully
evaluate preoperative parameters.

Conflicts of interest: On behalf of all authors, the corresponding
author states that there is no conflict of interest.

Funding: The study did not receive funding.

Ethical Standards:The study was approved by Beijing children's Hospital
Clinical New Technology and Research Ethics Committee.

\textbf{References:}

{[}1{]} Speer A L , Schofield D E , Wang K S , et al. Contemporary
management of lipoblastoma{[}J{]}. journal of pediatric surgery, 2008,
43(7):0-1300.

{[}2{]} Dishop M K, O'Connor W N, Abraham S, et al. Primary Cardiac
Lipoblastoma{[}J{]}. Pediatric \& Developmental Pathology the Official
Journal of the Society for Pediatric Pathology \& the Paediatric
Pathology Society, 2001, 4(3):276.

{[}3{]} Poonam S , Urmila S , Gita S , et al. Lipoblastoma: an unusual
tumour of the left ventricle{[}J{]}. European Journal of Cardio-Thoracic
Surgery(5):5.

{[}4{]} Tzani A , Doulamis I P , Mylonas K S , et al. Cardiac Tumors in
Pediatric Patients: A Systematic Review{[}J{]}. World Journal for
Pediatric \& Congenital Heart Surgery, 2017, 8(5):624-632.

{[}5{]} Chen C W , Chang W C , Lee H S , et al. MRI features of
lipoblastoma: differentiating from other palpable lipomatous tumor in
pediatric patients{[}J{]}. Clinical Imaging, 2010, 34(6):453-457.

{[}6{]} Mcvay M R , Keller J E , Wagner C W , et al. Surgical management
of lipoblastoma{[}J{]}. journal of pediatric surgery, 2006,
41(6):0-1071.\selectlanguage{english}
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