Case report
A 37-year-old male with a past medical history of hypothyroidy presented
to the emergency department with complaints of progressive exertional
dyspnea (NYHA class II-III), anorexia and epigastric pain for a couple
of days. The laboratory test results were unremarkable. Transthoracic
echocardiogram (TTE) and transesophageal echocardiogram (TEE) revealed
the presence of a left atrial mass of 40 X 26 mm originating from the
interatrial septum and causing a dynamic obstruction of the mitral
valve. The mass was attached by a narrow pedicle of 4 mm localized on
the interatrial septum between the fossa ovalis and the insertion of the
anterior mitral leaflet (Fig. 1). Cardiac magnetic resonance imaging
(MRI) confirmed the presence of a homogeneous atrial mass with isosignal
intensity on T1-weighted images and increased T2 signal, without
contrast enhancement after Gadolinium injection (Fig. 2).The most likely
diagnosis for this mass was a large myxoma and the patient was scheduled
for a surgical resection without delay.
Surgery was performed under a minimally invasive thoracoscopic approach
(small incision in the right 4th intercostal space, 2
percutaneous venous cannulas respectively inserted in the right internal
jugular vein and in the right femoral vein). A transseptal approach via
the right atrium was preferred in order to resect part of the
interatrial septum if needed. After incision of the interatrial septum,
we discovered a reddish, slightly gelatinous mass, attached to the lower
part of the interatrial septum by a small pedicle (Fig. 3). The pedicle
was resected with a small patch of the interatrial septum and the mass
was removed. The interatrial septum was closed directly without
interposition of a patch. Postoperative course was uneventful. Gross
pathology of the operative specimen showed an encapsulated mass of 4.3 X
3.2 X 2.4 cm with soft consistency. Microscopic examination revealed the
presence of a myxoid matrix with some cellular zone, in which spindle or
stellar cells are identified (Fig. 4). Some nuclear atypias were
present, however without abnormal mitotic figures. On this basis,
pathologic analysis confirmed the diagnosis of cardiac myxoma. Patient
was discharged from the hospital by day 7. One month after hospital
discharge, the patient was rehospitalized for bronchopneumonia and
atrial fibrillation (AF). The cardiac imaging by TTE and thoracic CT
performed at this time did not show any evidence of cardiac mass
recurrence. Patient was treated by antibiotics and antiarrhythmic drugs
with favorable clinical course. Four months after surgery, patient
experienced recurrent AF and the routine TTE showed a recurrence of a
left atrial mass of 26 X21 mm, with irregular shapes. TEE and cardiac
MRI confirmed the features of the mass that is attached to the atrial
septum at the same place as the previous tumor (Fig. 5). Although the
recurrence occurred early, the presumptive diagnosis at this moment was
a recurrent left atrial myxoma. A surgical resection of this recurrent
left atrial mass was performed under median sternotomy and
cardiopulmonary bypass. Due to recent history of paroxysmal AF, a
concomitant surgical AF ablation procedure (Cox-Maze 4) was performed in
the same operative time. A yellowish, slightly lobulated mass was
removed, excising part of the interatrial septum (Fig. 6). The defect in
the atrial septum was closed using a pericardial patch. Macroscopic
examination of the specimen demonstrated a mass of soft consistency
measuring 3.2 X 3 X 2.6 cm. Histology showed an edematous stromal tissue
with area of moderate to high cellularity. In these areas, packed
spindle cells and stellar cells are found with fascicular growth
pattern. The tumor cells had pleiomorphic, polylobed nuclei with
frequent abnormal mitotic figures. Immunohistochemical analysis revealed
an intense expression of the MDM2 oncogene in tumor cell nuclei,
confirming the diagnosis of intimal sarcoma (Fig. 7). Adjacent atrial
septum and resection margins were free of tumor. Early postoperative
evolution was favorable and patient was discharged home by day 9. An
adjuvant chemotherapy with doxyrubicin was administered for a total of 6
cycles. A metastasis in the left adrenal gland was discovered on the
PET-CT at 1-year follow-up. Patient underwent a successful surgical
resection of this metastasis and pathology confirm that it was a
metastasis of the intimal sarcoma. An additional adjuvant chemotherapy
with ifosfamide was given for 6 cycles and the patient is still in
complete remission 18 months after the first operation.