GPR: 2019 - Week 25

From MGH Learn Pathology

Clinical history

41 year-old woman with a 6 cm (4 months) mobile, nontender subcutaneous mass of the right inner thigh.


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Intramuscular myxoma
  • Adult females age 40-70
  • Large muscles
  • Most commonly less than 10 cm
  • Well-circumscribed, gelatinous-appearing cut surface with tan-white fibrous septae surrounding lobules
  • Can be associated with Mazabraud syndrome, which is characterized by skeletal fibrous dysplasia and intramuscular myxomas
 

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Low-grade fibromyxoid sarcoma

  • Young adults
  • Proximal extremities and trunk
  • Indolent, painless mass of the deep soft tissue that grows to an average size of 6 cm
  • Fibrous and myxoid cut surface that may be grossly infiltrative of the surrounding tissue
 

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Myxoid liposarcoma

  • Young to middle-aged adults
  • Arise in deep soft tissue of extremities
  • Average size of 10-12 cm
  • Well-circumscribed and multinodular with low grade tumors having a gelatinous surface and higher grade tumors having a more firm and opaque surface
 

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Myxofibrosarcoma

  • Most common sarcoma in patients 50-70 years
  • Arise in subcutaneous tissue or dermis of limbs and limb girdles in 2/3 of cases with the remainder in deep soft tissue
  • 2/3 recur, 1/4 metastasize (commonly to lung and bone)
  • Multiple myxoid nodules with the relatively rare higher grade tumors possessing infiltrative margins and tumor necrosis
 
Thanks to Diane Brackett for sharing the case!

This week's Gross Pathology Roundup was presented by Cameron Ray Smith, MD, PhD on Mon, Jun 17, 2019.