Context - DICER1-associated sarcomas are rare. These are currently
described under a wide variety of appellations; morphologic
characterizations in reported cases and sites of occurrence have also
been disparate. Design – We aimed to review pediatric sarcomas
associated with DICER1-mutation reported at our center, along with
literature review, to identify histologic hallmarks for diagnosis.
Results - A 12 year old girl with intracranial sarcoma mimicking
mesenchymal chondrosarcoma, a 16 year old girl with broad ligament
sarcoma mimicking fibrosarcoma and a 5 month old girl with vaginal
sarcoma mimicking embryonal rhabdomyosarcoma showed DICER1-mutation. All
three tumors though seemingly diverse, had an uncanny resemblance,
comprising of a primitive mesenchyme-like spindle cell component with
rhabdomyoblastic differentiation on immunohistochemistry. Primitive
blastema, chondroid differentiation and foci of anaplasia mimicking
pleuropulmonary blastoma histology were variably present. One case
showed primitive neuroblastic differentiation. Though the constellation
of features reported in literature is quite varied, rhabdomyoblastic
differentiation has been ubiquitously reported in tumours across sites.
Molecular testing showed gain of chromosome 8 in 2 cases. All 3 cases
responded to alternating Vincristine, doxorubicin and cyclophosphamide /
Cisplatin, etoposide and ifosfamide (VDC/PEI) backbone followed by
maintenance chemotherapy. Conclusion - We highlight this morphologic
hallmark of rhabdomyoblastic differentiation with or without chondroid
differentiation, in primitive appearing pediatric sarcomas, especially
of female genital tract and brain, which should raise a flag to test for
DICER1 pathogenic variation. This is crucial in low / middle income
countries where sequencing is not done routinely. Timely diagnosis can
ensure appropriate treatment and implementation of surveillance
protocols for those with germline mutation.