GPR: 2020 - Week 35

From MGH Learn Pathology

Clinical history

50 year old man with a history of multiple myeloma s/p bone marrow transplant and radiation.


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  • Malignant bone neoplasm usually centered in the metaphysis.
  • Has a gritty cut surface that is tan-white to grey.
  • The mineralized bone will be tan-white and hard while the cartilaginous elements are greyish in color with a consistency ranging from mucinous if the matrix is myxoid and rubbery if the matrix is hyaline.

GPR20-11 -mm1.jpg


Recurrent Multiple Myeloma

  • Bone marrow based plasma cell neoplasm.
  • The classic gross appearance is a tan-red soft friable lesion that has fragile or eroded surrounding bone.




  • Can be low or high grade.
  • Low grade cartilaginous neoplasms can fill the medullary cavity and expand the bone causing thickening of the cortex.
  • While high grade chondrosarcomas can destroy the cortex and form soft tissue masses.
  • The cartilaginous areas are a glistening grey color and have a lobulated architecture that can be interspersed with thin fibrous septa.




  • This is a benign bone forming neoplasm that is comprised of woven bone trabeculae and lined with osteoblasts.
  • Most frequently arises from appendicular skeleton and can be centered in either the cortex (65%) or medullary cavity (35%).
  • It usually presents as a solitary well circumscribed, tan white, dark red, and gritty boney mass that may have some cystic changes.
  • Dr. Hung
  • Dr. Nielsen
  • Dr. Sohani

This week's Gross Pathology Roundup was presented by Leif Timothy Helland, MD on Mon, Aug 24, 2020.