Malignant Ectomesenchymoma: Series Analysis of a Histologically and Genetically Heterogeneous Tumor

Abstract

Our analysis extends the histologic and molecular spectrum of these tumors and highlights their heterogeneity. The percentage of cases with alveolar rhabdomyosarcoma or primitive neuroectodermal-like tumor components suggests that these types of elements might be underreported. This study is also the first to demonstrate FOXO1 gene rearrangements in malignant ectomesenchymoma with alveolar rhabdomyosarcoma subtype.

Primary intracranial malignant ectomesenchymoma in an adult: Report of a rare case and review of the literature

“…Similarly Huang et al observed a genetic link between these two tumors by demonstrating frequent HRAS mutations in MEM (5/7 cases) by Sanger sequencing overlapping with RAS mutations seen in an ERMS control group . The work by Griffin et al in addition supported the hypothesis that MEMs may represent a variant of RMS by demonstrating FOXO1 gene rearrangements by reverse transcription polymerase chain reaction in all three out of six cases of MEM with alveolar RMS histology . Additionally, Nael et al and Sorensen et al have recognized EWSR1 gene rearrangements (t(11;22)) in MEM in their respective works.…”

“…7 The work by Griffin et al in addition supported the hypothesis that MEMs may represent a variant of RMS by demonstrating FOXO1 gene rearrangements by reverse transcription polymerase chain reaction in all three out of six cases of MEM with alveolar RMS histology. 21 Additionally, Nael et al 22 and Sorensen et al 23 have recognized EWSR1 gene rearrangements (t (11;22)) in MEM in their respective works. In contradiction to the above studies, recently Kleinschmidt-DeMasters et al found gene expression pattern of MEMs clustered closely with MPNSTs and not with RMS or EWS using microarray testing.…”

Primary uterine ectomesenchymoma harboring a DICER1 mutation: case report with molecular analysis

“…Though isolated reports of tumors diagnosed in adults have been published [ 6 , 7 ], the age of the patient in this report is exceptional. Similarly, whereas location of the primary tumor in the abdomen, pelvis, groin, perineum, paratesticular region, and vulva has been reported [ 2 – 5 ], ectomesenchymoma has not, to the best of our knowledge, been diagnosed as a primary uterine tumor to date. One possibility which cannot be entirely ruled out is that this tumor developed from a carcinocarcinoma.…”

“…The majority of patients diagnosed with ectomesenchymoma are pediatric [ 2 – 5 ]. Though isolated reports of tumors diagnosed in adults have been published [ 6 , 7 ], the age of the patient in this report is exceptional.…”

“…Previous molecular studies of ectomesenchymoma have shown chromosomal changes (trisomy, polyploidy, or focal gains) involving chromosomes 2, 6, 8, 9, 10, 11, and 20, as well as t(12;15)(p12.3;q24.1) and t(1;12)(p32;p13) fusions, the latter with no rearrangement of ETV6 [ 8 – 12 ]. Griffin et al found FOXO1 gene rearrangements by RT-PCR in three cases with alveolar RMS morphology, of which two involved PAX3-FOXO1 fusion, and one harbored PAX7-FOXO1 translocation [ 5 ]. Whole genome/exome sequencing studies of this tumor are to date limited to one report.…”