Introduction :
The DICER1 -tumor predisposition syndrome (OMIM 6012000) is an
autosomal dominant disorder with incomplete penetrance and exhibits
multiple tumors over time in affected kindreds. 1-6 It
is characterized by heterozygous germline mutation in DICER1
gene.4 DICER1 -associated tumors can also be due
to biallelic somatic mutations and can be grouped into sarcomas and
non-sarcomatous tumors. These comprise a varied spectrum of unrelated
benign to malignant tumours, as well as non-neoplastic entities.7-9 DICER1 -associated sarcomas have been
reported in literature under a varied list of appellations such as
pleuropulmonary blastoma (PPB; the prototype), embryonal
rhabdomyosarcoma (ERMS), anaplastic sarcoma of kidney, adenosarcoma,
primitive intracranial sarcoma, carcinosarcoma, fibrosarcoma,
leiomyosarcoma, primitive neuroectodermal tumour (PNET), mesenchymal
chondrosarcoma and more recently PPB-like peritoneal sarcoma.7-9 It is increasingly being recognized that these
sarcomas may be morphologically similar enough for a unified terminology
- DICER1 -associated sarcoma. 7,10
We present a series of three DICER1 -associated extrapulmonary
sarcomas, each of whom presented with a spindle cell sarcoma of
primitive morphology and rhabdomyoblastic differentiation on
immunohistochemistry and did not respond to conventional
rhabdomyosarcoma chemotherapy. We compared the morphology with that of
other reported DICER1 -associated sarcomas to identify morphologic
clues to guide appropriate molecular testing for diagnosis of these
tumours.