Bone Abnormalities in Bone Marrow Specimens



Bone Abnormalities in Bone Marrow Specimens


Kathryn Foucar, MD





Key Facts


Terminology



  • Bony trabeculae composed of central, mineralized, mature bone and peripheral, newly formed unmineralized bone matrix termed osteoid


  • Provide support for bone marrow microenvironment and HP meshwork


  • Marked variations in bony trabeculae and osteoblastic and osteoclastic activity based on age and gender


  • Osteoblasts, mesenchymal stem cell-derived cells



    • Produce osteoid


    • Play key role in regulation of HP


  • Osteocytes are osteoblasts that have been internalized within lacunar spaces of mineralized bone



    • Play key role in bone homeostasis


    • Undergo apoptosis with aging


  • Osteoclast, HP stem cell-derived



    • Multinucleated bone resorbing-cell of monocyte/macrophage lineage


  • Prominent bone remodeling normal in children


  • Substantial amounts of unmineralized osteoid in specimens from infants and very young children


  • Thicker bony trabeculae and greater bone remodeling in adolescent/young adult males compared with females and older adults


  • Types of bone disorders



    • Osteopenia, osteoporosis


    • Osteolysis, osteonecrosis


    • Osteosclerosis


    • Renal osteodystrophy


    • Paget disease


    • Osteomalacia


    • Osteopetrosis






Bone marrow core biopsy from a 12-year-old boy shows active bone remodeling with patches of unmineralized bone image, several osteoclasts image, and osteoblastic rimming image, all normal in a child.






This bone marrow core biopsy section is from a 52-year-old man and illustrates normal adult bone. Note the smooth contours of the bony trabeculae and the absence of overt remodeling.


TERMINOLOGY


Definitions



  • Bony trabeculae and associated cellular constituents are evident on all core biopsy sections


  • Bony trabeculae composed of central, mineralized, mature bone and peripheral, newly formed unmineralized bone matrix termed osteoid



    • Provide support for bone marrow microenvironment and hematopoietic (HP) meshwork


    • Marked variations in bony trabeculae and osteoblastic and osteoclastic activity based on age and gender


  • Osteoblasts, mesenchymal stem cell-derived



    • Produce osteoid


    • Play key role in regulation of HP


  • Osteocytes are osteoblasts that have been internalized within lacunar spaces of mineralized bone



    • Key role in bone homeostasis


    • Likely induce osteoclast and osteoblast activity in response to bone injury


    • Undergo apoptosis with aging


  • Osteoclasts, hematopoietic stem cell-derived



    • Multinucleated bone-resorbing cell of monocyte/macrophage lineage


    • Resides with Howship lacunae along periphery of bony trabeculae


  • Types of bone disorders/conditions evident on iliac crest bone marrow core biopsy section



    • Age-/gender-related variations



      • Prominent bone remodeling in children


      • Substantial amounts of unmineralized osteoid in specimens from infants and very young children


      • Thicker bony trabeculae and greater bone remodeling in adolescent/young adult males compared with females and older adults


    • Osteopenia



      • Thinning of bony trabeculae


      • Imbalance of bone homeostasis


      • Reduced new bone formation


      • Termed osteoporosis if generalized and associated with reduced bone density testing


    • Osteolysis



      • Discrete area of excessive osteoclast-induced bone resorption


    • Osteonecrosis



      • Nonviable bony trabeculae with loss of osteocytes within lacunar spaces


      • May be associated with necrosis of medullary (HP) cavity


    • Osteosclerosis



      • Thickened bony trabeculae that may be anastomosing


      • Radiographically apparent when generalized and prominent


      • Often associated with fibrosis


      • Linked to neoplastic and nonneoplastic disorders of bone and bone marrow


    • Renal osteodystrophy



      • Variable features of bony trabeculae and bone marrow stroma over time


      • Spectrum of sequelae from low and high bone turnover


      • Bone erosion, bone formation, and quiescent phases


      • May see bony trabecular changes linked to secondary hyperparathyroidism


      • May see changes linked to osteomalacia with defective mineralization


      • May see bone islands within medullary space


    • Osteomalacia



      • Excessive osteoid formation with defective mineralization


      • Linked to selected renal disorders


      • Constitutional and acquired types


    • Paget disease



      • May be familial


      • Increased osteoclastic and osteoblastic activity



      • Disorganized woven bone


    • Osteopetrosis



      • Constitutional disorder caused by mutations in genes expressing proteins linked to osteoclastic bone resorption


      • Markedly expanded and confluent bony trabeculae with increased bone density and dramatically reduced HP space


ETIOLOGY/PATHOGENESIS



  • Complex mechanisms necessary for bone homeostasis


  • Adequate calcium phosphorus, vitamin D, and other factors necessary


  • Normal numbers and function of osteoblasts, osteoclasts, osteocytes, vasculature, stem cells, and regulatory factors required


  • Factors that elicit bone marrow fibrosis may affect bony trabeculae


  • Age-related factors including estrogen deficiency linked to osteocyte apoptosis and loss of regulation of bone remodeling by osteocytes


  • Constitutional disorders linked to defective function of osteoclasts and other key constituents of bone homeostasis


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Osteopenia/osteoporosis very common in elderly, especially postmenopausal women


    • Osteosclerosis elicited by many neoplastic and nonneoplastic disorders



      • Generally occurs in adults


      • No gender predilection


    • Rare constitutional disorders such as osteopetrosis and some types of osteomalacia manifest in infancy, early childhood



      • Severe hematopoietic compromise is characteristic


Laboratory Tests



  • Comprehensive biochemical assessment of bone constituents and factors linked to bone formation, resorption, and remodeling


  • Tests for renal and parathyroid function


  • Various methodologies to assess bone


Treatment



  • Highly variable, dependent on type of bone abnormality and underlying disorders


  • Bone marrow transplant in infancy necessary in constitutional disorders such as osteopetrosis


Disease Course



  • Highly variable and dependent on type of bone abnormality and potential underlying neoplastic and nonneoplastic disorders


MICROSCOPIC PATHOLOGY


Blood



  • Highly variable blood picture depending on underlying cause of bony trabeculae abnormalities


Bone Marrow Aspirate



  • Highly variable aspirate smears depending on underlying cause of bony trabeculae abnormalities


  • Bone marrow frequently inaspirable in cases with associated bone marrow fibrosis


Bone Marrow Core Biopsy

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Jun 13, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Bone Abnormalities in Bone Marrow Specimens

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