Congenital Infantile Fibrosarcoma Involving Pelvic Wall and Thigh Soft Tissues and Placenta, Presenting with Coagulopathy

Brianna Naumchik, Brenda J. Weigel, Michael A. Murati, Erin Rudzinski, Vera Paulson, Christina M. Lockwood, Michelle Dolan, Siobhan Flanagan, Mark Luquette

Research output: Contribution to journalArticlepeer-review


Infantile fibrosarcoma (IF) is a well characterized pediatric malignancy marked by gene rearrangements involving members of the NTRK family. In this report, we present a case of IF that presented in the inguinal region-proximal thigh and was initially thought to be a kaposiform hemangioendothelioma (KHE) because it presented with a bleeding diathesis thought to be Kasabach-Merritt phenomenon (KMP). Subsequently, the placental examination showed a neoplasm in the perivascular-subendothelial space of stem villi, initially thought to be myofibromatosis. Ultimately, a biopsy of the thigh mass showed IF with an NTRK3-ETV6 fusion. Subsequent FISH analysis of the placenta showed an ETV6 rearrangement confirming that it was also IF. Review of the laboratory studies suggests that disseminated intravascular coagulation may have been more likely than KMP, highlighting the difficulty in making this distinction in some cases. We believe this to be the first report of an IF presenting in a soft tissue site and the placenta, and discuss the possible mechanisms that could have allowed the IF in the leg to spread to the placenta.

Original languageEnglish (US)
Pages (from-to)656-660
Number of pages5
JournalPediatric and Developmental Pathology
Issue number6
StatePublished - Nov 1 2022

Bibliographical note

Publisher Copyright:
© 2022, Society for Pediatric Pathology All rights reserved.


  • embryo
  • infantile fibrosarcoma
  • kasabach-merritt phenomenon
  • metastasis
  • placenta
  • vascular malformation

PubMed: MeSH publication types

  • Case Reports
  • Journal Article


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