DISCUSSION
To this date, this hybrid SEF-LGFMS tumor with an EWSR1/CREB3L1 fusion
has not been described in the literature as a primary lung neoplasm.
Only one other EWSR1/CREB3L1 hybrid SEF-LGMS tumor has been reported, a
10-year-old primary renal tumor (7). The patient presented with
widespread metastases, underwent biopsy and subsequent palliative
chemotherapy; the patient died of metastatic disease 12 months after the
diagnosis.
In contrast, the EWSR1/CREB3L1 gene fusion has been observed in 80-90%
of SEF (a rare soft-tissue sarcoma) cases (8). The youngest patient
reported with SEF and an EWSR1-CREB3L1 mutation was a 3-year-old who
presented with numerous lung and bone metastases (8). In a case series
of four pediatric patients with SEF in deep soft tissues of the trunk
harboring EWSR1-CREB3L1 mutations, one patient did not receive further
treatment and died 17 months after diagnosis, two remained disease-free
post-surgery, and one remained disease-free 22 months following
radiation and multiple chemotherapy cycles (9). A review of 51 SEF cases
(4/51 pediatric) found that 10% of primary SEF tumors occurred in the
lung, while 42.1% of metastatic tumors were found in the lung/pleura
(10).
LGFMS is an indolent tumor with metastatic potential and has only been
reported in 33 pediatric patients. As with hybrid SEF-LGFMS tumors, most
LGFMS cases display FUS-CREB3L2 mutations; only four case reports thus
far demonstrate EWSR1-CREB3L1 fusion mutations in LGFMS (with primary
tumors of the orbit, lower leg, thigh, and kidney) (11,12). Of the two
pediatric patients with EWSR1-CREB3L1 LGFMS, one presented with a
subcutaneous nodule on the lower leg and is disease-free 12 months after
excision; the other presented with a primary renal solid tumor and was
disease-free 18 months post-surgical excision of solely the encapsulated
mass (12).
This is only the second reported case of the use of robotic bronchoscopy
in a pediatric patient. Though a specimen was obtained safely in our
patient, it was not diagnostic, and an additional specimen was obtained
surgically (13). There is a need for less invasive sampling of lung
lesions in the pediatric population. Clinicians choose between surgical
sampling and less often, flexible bronchoscopy with endobronchial or
transbronchial biopsy. Robotic assisted bronchoscopy has recently joined
this list as an option, due to its stability, adjustability, and
peripheral visualization (14).
This unique case provides insight into the clinical and pathologic
presentation of a EWSR1-CREB3L1 driven primary lung hybrid SEF- LGFMS,
further broadening the molecular spectrum of pediatric lung tumors.
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