DISCUSSION
Oncological diseases account for 80-90% of the reported cases of SVCS.
The frequency of mediastinal mass in T-LBL/T-ALL ranges from 66-90% in
adult studies and is more in mature T-ALL phenotypes (6). One study
identified that almost 50% of children with mediastinal masses
presented in emergency with respiratory distress, dyspnea, cyanosis, and
they needed immediate intervention (7). Of our patients, 48% of the
T-ALL/T-LBL patients presented with SVCS. The most common reason for
this presentation is due to the mechanical obstruction caused by the
mediastinal mass. Additionally, pleural and/or pericardial effusions may
be present which may be diagnosed clinically or radiologically.
SVCS is an oncological emergency requiring prompt commencement of
treatment aimed at rapid tumor debulking with intensive chemotherapy
and/or radiation therapy, as indicated or feasible. PICU support
includes managing airway and circulation , renal replacement therapy
etc. (8).
In our cohort, mediastinal widening on X-ray was noted in all patients.
72% of patients required PICU stay. Supplemental oxygen was required in
82%, and endotracheal intubation was required in 18% of our patients.
None of our patients required inotrope support or renal replacement
therapy. Morin et al. described the clinical presentation and critical
care needs of 50 cancer patients (60% hematological malignancy and 40%
solid tumor), median age 37 years(25-29years), presenting with SVCS.
Pleural effusion, pulmonary atelectasis and pulmonary embolism were seen
in 66%, 32%, and 10% patients respectively. Pericardial effusion on
echocardiography was noted in 44% patients. Critical care unit
interventions like intubation was required in 30%, inotrope infusion in
14% and renal replacement therapy in 6%. Pleural and pericardial
drainage was performed in 26%, and 8% patients, respectively (9).
Another study from India analyzed 55 patients of T-LBL patients with
mediastinal mass with a median age of 18years, 36/55 presented with
SVCS. Pleural effusion was seen in 71%, and pericardial effusion was
seen in 52% (10).
These patients at presentation are very sick and need urgent
commencement of treatment for onset of relief. Invasive painful
procedures like bone marrow test or trucut biopsy to reach a diagnosis
that requires anesthesia/sedation may not be desirable and feasible
since SVCS may confer a higher risk of airway collapse and difficult
intubation and ventilation. Also, delays that happen in the process of
doing diagnostic tests may be circumvented when these tests can be done
reliably on accessible body fluid samples like peripheral blood/ pleural
fluid/ pericardial fluid. In our patients, pleurocentesis and
pericardiocentesis were done in 36% patients each as therapeutic
measure and the fluid was sent for morphology and Flow cytometry which
helped in prompt diagnosis. Flow cytometry could identify blasts on
peripheral blood and pericardial/ pleural fluid in 90% of patients.
Flow cytometry has long been known to detect blasts in peripheral blood
and bone marrow aspirate; however, its efficacy in the detection of
blasts on non-hematic body fluids is less well established. Several
published data have shown the indispensable role on Flow cytometry in
diagnosis and early initiation of treatment including that by Bhaker et
al. who evaluated 15 samples from pediatric patients (6-15 years) with
Precursor T-cell Lymphoma, and, Czader et al. who analyzed 115 serous
cavity effusions from patients aged 2-80yeras of age( mean age- 56
years) with malignant effusion (11) (12). Cesana et al. on 2 different
occasions has also demonstrated the same (13) (14).
After initial stabilization, most of the patients in our cohort had an
expected course of treatment during the remaining part of the induction
chemotherapy. Out of the 11 patients, 3 patients abandoned treatment at
various time points. Of the remaining 8 patients, 6 are alive and in
remission at last follow-up. Treatment related mortality was noted in
only 1 patient. The OS and EFS of the cohort was 75%. Morin et al.
studied 50 patients with cancer and SVCS aged 25-59 years, median 37
years) and reported an overall mortality rate at 6 months of 48% (9).
Tilak et al. in their study of 55 de novo T-LBL ( age 3-36 years, median
18 years), have reported a 5-year OS of 59.8% (10). In a systematic
review of pediatric SVCS cases by Nossair et al. the overall morbity and
mortality was 30% and 18% respectively (15). In our study, 3/11(27%)
patients abandoned treatment at various time points. Various other
studies have also shown that treatment abandonment is a big barrier to
improving outcomes for children with cancer in the developing world (16)
(17). Treatment related mortality is also another major hurdle to
improving the outcomes of pediatric oncology patients. In our cohort we
lost one patient to treatment related complication.
Pediatric data of the presentation, course, management, outcome, and
critical care needs of this cohort are limited, and it is difficult to
approach such children safely. In our study, flow cytometry on
peripheral blood and non-hematological fluids served as a valuable tool
in diagnosing patients and prompt initiation of treatment. Despite the
life-threatening initial presentations, timely initiation of specific
therapy and effective critical care supportive treatment could improve
the outcomes of this cohort.
Patients with SVCS, despite their life-threatening presentations of
airway collapse, cardiac tamponade and shock, can have improved outcomes
with good intensive care treatment and timely interventions. Utilizing
flow cytometry for detection of blasts in peripheral blood/pleural
fluid/pericardial fluid and delaying invasive procedures like bone
marrow test and tissue biopsy in a clinically unstable child is a
preferable option.
Disclosure – All authors have nothing to declare.