Inflammatory myofibroblastic tumor arising from soft tissues of extremities harboring a novel CLIP2-ALK fusion

Pathol Int. 2020 Oct;70(10):798-803. doi: 10.1111/pin.12988. Epub 2020 Jul 27.

Abstract

A 34-year-old Chinese woman found a lump in her left leg for more than 3 weeks without any discomfort. Grossly, the tumor was relatively well delineated with focal infiltration. Histopathologic evaluation showed a compact fascicular spindle cell proliferation with variable myxoid and collagenous stroma and scattered inflammatory infiltrate. Immunohistochemically, the tumor cells showed positive expression of ALKD5F3 and SMA and negative expression of CD34, desmin, and cytokeretin. Fluorescence in situ hybridization analysis of the ALK locus showed break-apart signals in 20% of tumor cells, and DNA sequencing discovered a novel CLIP2-ALK fusion gene. The lesion was diagnosed as an inflammatory myofibroblastic tumor (IMT). To the best of our knowledge, this is the first case with CLIP2-ALK gene fusion in the somatic soft tissue IMTs.

Keywords: ALK; CLIP2; inflammatory myofibroblastic tumor; somatic soft tissue.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Anaplastic Lymphoma Kinase / genetics*
  • Anaplastic Lymphoma Kinase / metabolism
  • Female
  • Gene Fusion
  • Humans
  • Immunohistochemistry
  • In Situ Hybridization, Fluorescence
  • Leg / diagnostic imaging
  • Leg / pathology
  • Microtubule-Associated Proteins / genetics*
  • Microtubule-Associated Proteins / metabolism
  • Neoplasms, Muscle Tissue / diagnostic imaging*
  • Neoplasms, Muscle Tissue / genetics
  • Neoplasms, Muscle Tissue / pathology
  • Soft Tissue Neoplasms / diagnostic imaging*
  • Soft Tissue Neoplasms / genetics
  • Soft Tissue Neoplasms / pathology

Substances

  • Microtubule-Associated Proteins
  • cytoplasmic linker protein 115
  • ALK protein, human
  • Anaplastic Lymphoma Kinase