Keywords
cardiovascular surgery - cardiac anatomy/pathologic anatomy - histology - mediastinal
tumor
Introduction
Malignant lymphoma of the heart is relatively common but difficult to detect. A small
number of studies have discussed this subject in the literature.[1]
Primary cardiac lymphomas account for ∼1% of primary cardiac tumors and 0.5% of extranodal
lymphomas. In contrast, disseminated lymphoma with cardiac involvement can occur in
up to 20% of patients with lymphoma. Approximately 80% of primary cardiac lymphoma
cases in immunocompetent hosts are diffuse B-cell lymphomas, and in immunodeficient
patients, small noncleaved or immunoblastic lymphomas are more frequent. Most cardiac
lymphomas are diagnosed postmortem via autopsy, but current data show a decrease from
64% of cases to only 15%. Common sites of cardiac infiltration by primary cardiac
lymphomas are the right atrium, the right ventricle, and the left atrium, followed
by the left ventricle.[1]
[2] Infiltration of the great cardiac vessels is rare and appears to be caused by invasion
of the mediastinal structures with connection to the lymphatic circulation or blood
vessels.[3] Here we present a case of a giant B-cell lymphoma with pulmonary vascular invasion
mimicking acute pulmonary embolism.
Case Report
A woman in her 30s, suffering from severe dyspnea and repeated syncope after a recent
cesarean section, was transferred to our hospital with suspected fulminant pulmonary
embolism for further investigation and treatment. Laboratory findings revealed increased
liver enzymes and D-dimer levels, as well as an elevated NT-pro-BNP level of 6,825
pg/mL. Electrocardiography showed sinus tachycardia (115 beats per minute) with right
axis deviation but no further signs of pulmonary embolism. Echocardiography revealed
normal left ventricular function and markedly reduced right ventricular function with
associated pressure and volume overload, tricuspid annular plane systolic excursion
(TAPSE) of 12 mm, and tricuspid regurgitation with a systolic pulmonary pressure of
80 mm Hg above the central venous pressure.
Despite the lack of sonographic evidence of deep vein thrombosis, computed tomography
(CT) angiography revealed subtotal occlusion of the pulmonary arterial trunk and the
left pulmonary artery. Catheter-based local lysis therapy with a recombinant tissue-type
plasminogen activator was initiated.
Despite the lysis, the patient deteriorated within 24 hours. Due to progressive cardiogenic
shock and resuscitation, mechanical circulatory support via venoarterial extracorporeal
membrane oxygenation (VA-ECMO) through the right femoral vessels was initiated. Repeat
CT angiography ([Fig. 1A]) confirmed subtotal occlusion of the pulmonary trunk and pulmonary bifurcation,
while all lobar pulmonary arteries were free from thrombus formation ([Fig. 1B]). Due to the severe cardiogenic shock, we decided not to perform a catheter-based
biopsy of the findings, especially as this would not have improved the clinical condition.
After discussion with the cardiology team, the patient was transferred to the operating
room for high-risk surgical intervention.
Fig. 1 (A) Computed tomography (CT) angiograph revealing tumor mass. (B) Chest radiograph demonstrates prominent pulmonary artery segment on the left side
and lysis catheter in the right pulmonary artery. Arrow indicates tumor mass in the
pulmonary trunk.
Intraoperatively, surgeons identified a mediastinal mass arising from the left lobe
of the thymus gland with infiltration of the pulmonary trunk. The mass grew invasively
into the lumen of the pulmonary trunk and extended to the right and left pulmonary
arteries while the outflow of the lobar pulmonary arteries remained tumor free. Due
to the clinical urgency of the case and its unexpected findings, an instantaneous
section was not possible. Under suspicion of angiosarcoma, the mass was radically
resected, necessitating replacement of the pulmonary trunk and both pulmonary arteries
with a vascular T graft. The right pulmonary artery was replaced by an 18-mm Hemashield
graft (Vascular Graft AlboGraft Polyester), which was connected end to side to a 26-mm
Hemashield graft (Vascular Graft Hemashield Platinum), which was interposed between
the pulmonary root and the distal left pulmonary artery. Despite uneventful surgery,
prolonged right heart failure and respiratory distress required postoperative ECMO
and inhalational nitric oxide (NO) support. The patient was weaned from ECMO support
and NO-inhalation therapy on the third and fourth postoperative days, respectively.
Extubation was possible on the sixth postoperative day. After further recovery, the
patient was transferred to the hematology department for immediate chemotherapy. However,
due to the histological findings (see below) and R0 resection, no chemotherapy was
initiated. The patient had a full recovery, was discharged to a rehabilitation center,
and then home. Six months after the operation, the patient was free of any symptoms
and tumor relapse.
The primary histopathological examination confirmed a complete excision of a 7 cm × 6 cm
gray-brown, plain tumor mass ([Fig. 2]), with spindlelike cells and increased proliferative activity consistent with a
B-cell lymphoma ([Fig. 3]). The final histopathological diagnosis confirmed an intermediary lymphoma with
histopathological signs of both non-Hodgkin's and B-cell lymphoma, and a high-grade
expression of pleomorphic CD20-positive blasts and lymphocytic small cells positive
for CD3+ and CD5+.
Fig. 2 Mediastinal giant B-cell lymphoma infiltrating the great cardiac vessels. Intraoperative
view after opening (A) the pulmonary trunk with direct view of the tumor mass and (B) subsequent reconstruction of the pulmonary vessels with a polyester graft.
Fig. 3 Histopathological examination of the resected intraluminal mass. Hematoxylin and
eosin staining showing infiltration to the (A) pulmonary artery and (B) numerous blast cells.
In the CT scan analysis, we had found no evidence for an origin of this B-cell lymphoma
except in the heart. The question remains if the B-cell lymphoma really primary originated
from the heart or if it secondary infiltrated in the pulmonary artery.
Due to the tumor board decision and the fact that it was an R0 resection, the decision
was made not to adjuvant chemotherapy. The clinical and technical follow-up controls
should be performed using positron emission tomography and CT (PET-CT).
To our knowledge, this is the first report of a primary mediastinal lymphoma infiltrating
the great vessels of the heart and causing life-threatening cardiogenic shock.
Discussion
Primary cardiac lymphomas are extremely rare, and their pathogenesis remains unclear.
With nonspecific clinical manifestations, most primary cardiac lymphomas are of B-cell
lineage and have poor prognosis.[2] Large B-cell lymphomas represent the majority of cardiac lymphomas, with up to 59%
in several case studies, followed by other histologic subtypes, such as T-cell lymphoma
(5%), Burkitt's lymphoma (7%), and small lymphocytic lymphoma (4%).[2]
The predominant clinical features in up to 34% of these cases were signs of heart
failure, while up to 20% did not show these signs. Depending on their location and
growth, lymphomas only become clinically evident with features such as pericardial
effusion, symptoms of heart failure, or even sudden cardiac death. Most patients typically
suffer from dyspnea, as well as nonspecific chest pain, atrial fibrillation, and other
arrhythmias. The median survival after diagnosis is 3 months (range: 0–72 months),
and patients with initial presentations of heart failure had poorer outcomes. Patients
with primary cardiac involvement had better outcomes than those with secondary tumors.[4]
The sensitivity and specificity of different clinical imaging modalities vary. Chest
radiography may only demonstrate signs of cardiomegaly. Transthoracic echocardiography
is an excellent noninvasive diagnostic tool, while transesophageal echocardiography
(TEE) is a more sensitive but invasive technique. CT can demonstrate the morphology,
location, potential infiltration, and extent of cardiac structures. Magnetic resonance
imaging provides excellent soft-tissue imaging and can further evaluate cardiac function
and intracardiac blood flow. Furthermore, 18F-fluorodeoxyglucose PET is considered an invaluable diagnostic tool for revealing
and differentiating cardiac infiltrations.[5]
[6]
[7]
[8] Nevertheless, accurate pathological diagnosis is critical to the decision-making
process for further disease management.
Our patient had an unusual presentation of classic Hodgkin's lymphoma (mixed cellularity)
with an intravascular tumor mass clinically simulating a fulminant pulmonary embolism.
Acute right heart failure and extracorporeal life support required emergency surgical
intervention. Although CT imaging was not completely consistent with pulmonary embolism,
the intraoperative finding was surprising and required complex allogenic reconstruction
of the central pulmonary artery. This case highlights the importance of early and
multidisciplinary decisions in patients with life-threatening signs of pulmonary embolism.
