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Histiocytic sarcoma or Osteosarcoma? That is the question.

  1. Histiocytic  sarcoma   or  osteosarcoma... That is the question
  2. Jerri  McIntosh •  10yo FN Rottweiler •  Referred to the SAH Oncology service for “treatment/mgmt of an osteosarcoma” •  A month ago: suddenly yelped & became non-weight bearing lame whilst running about •  At local vet’s: radiographs (& referral) + tramadol + advised strict rest
  3. History •  EDDU all fine •  had adhered to rest instructions - only let out to garden •  left forelimb lameness improved but not entirely •  generally happy at home though the tramadol made her quite sedated •  known right forelimb osteoarthritis of 3 years duration •  has meloxicam for that
  4. Clinical  exam •  bright & alert •  visibly lame on left fore but mostly weight-bearing •  feeling the limb, noted a firm swelling of muscle-&- soft-tissue consistency •  local draining lymph nodes (prescaps, axillary) not palpably enlarged or firm •  NAD on chest auscultation and abdominal palpation
  5. Radiographs  sent Ulna involvement - unusual
  6. Radiographs  sent No pulmonary metastatic nodules were seen on chest radiographs
  7. Our  plan  of  action o  routine bloodwork (haem & biochem) o  CT scan of elbows (both) o  CT scan of thorax o  Abdominal ultrasound scan o  FNA of the swelling •  in-house + sent up to the clinical pathology unit •  multiple slides to account for variation within the lesion The obligatory metcheck
  8. Test  results  /  findings •  Routine blood work o  Haematology unremarkable. o  Biochemistry mild elevation of AST but no increase in ALP (often seen with OSAs) •  Abdominal ultrasound scan NAD
  9. CT  thorax  (lung  window)
  10. Diagnostic imaging dx: Large aggressive soft tissue lesion with invasion and destruction of proximal left ulna - likely neoplastic. CT  forelimbs  (bone  &  soft  tissue  windows)
  11. Right elbow also showed aggressive lytic change, Centred especially on right medial humeral condyle. CT  forelimbs  (bone  &  soft  tissue  windows)
  12. FNAs  &  cytology •  High numbers of roundish/polygonal cells, many with multiple nuclei •  Anisocytosis and anisokaryosis •  Some spindle cells, many of which were binucleate and had multiple nucleoli •  Monomorphic population of mesenchymal cells exfoliating individually and in aggregates… •  Associated with amorphous, pink extracellular matrix (osteoid or collagen)… •  Cells ranging in shape from oval to polygonal to spindle… •  Nucleus round to oval, often eccentrically located…
  13. Types  of  tumours  that  can   affect  bone  in  dogs •  Osteosarcoma •  Chondrosarcoma •  Fibrosarcoma •  Haemangiosarcoma •  Rhabdomyosarcoma •  Histiocytic sarcoma Metastatic tumors that may present clinically as bone tumors: •  Carcinomas •  Plasma cell myeloma
  14. Osteosarcomas •  85-90% of primary bone tumours •  Appendicular skeleton > axial skeleton •  large and giant breeds >> small breeds •  Predilection sites: away from the elbow, towards the knee
  15. Osteosarcomas •  Transformed malignant cell is the osteoblast •  Neoplastic cells often round/ovoid Cowell  &  Tyler  –  cells  from  a  canine  osteosarcoma and not
  16. Histiocytic  sarcomas   •  transformed malignant cells are interstitial dendritic antigen-presenting cells (APCs) •  Uncommon in dog population as a whole •  But tremendously common in certain breeds Cowell  &  Tyler  –  aspirate  from  a  histiocytic  sarcoma Round,  discrete  cells!
  17. Histiocytic  sarcomas •  2 forms o  Localised •  deep limb musculature and periarticular •  Highly malignant and metastatic o  Disseminated •  both localised and disseminated forms carry quite a guarded prognosis
  18. Back  to  Jerri… Histiocytic  sarcoma? Osteosarcoma?
  19. Jerri’s  FNA  slides  -­‐‑   discussion •  Cytology can be rewarding but also confusing, especially to the unpractised eye •  Special cytochemical stains available o  BCIP/NBT solution stains ALP in osteoblasts o  ANBE stains intracellular esterase enzymes that are present in cells of dendritic/ monocytic origin •  Variation amongst different sites of the lesion sampled Provisional diagnosis: Lytic bone tumour of left ulna. Sarcoma.
  20. Treatment  options •  Amputation + follow-up with chemo = first-line •  Radiotherapy •  More analgesics o  e.g. tramadol , fentanyl patches •  Bisphosphonates o  help reduce bone lysis and pain Palliative intent
  21. Considerations •  Tried simulating a left forelimb amputation by bandaging it up •  The worrying CT scan findings o  Pulmonary metastases – prognosis slightly poorer (though early stage metastatic disease as not detected on radiography yet) o  Compromised right elbow – arthritic change + possible neoplasm as well
  22. Recommendations  and   owner’s  decision •  Radiotherapy •  +/- chemotherapy to follow o  explained would be much less effective as, even though irradiated, whole mass still there •  +/- bisphosphonates and additional analgesic medication Jerri went home on metacam SID and she’s scheduled to come in week commencing 15 sept for a 5d course of radiotherapy (palliative intent)
  23. Updates •  Owner has called on 2 occasions o  Worried about Jerri’s lameness o  Wondering if can XRT both forelimbs – going to give it a go •  Jo also thinking of doing a repeat FNA (just for interest’s sake) o  Definitive diagnosis more important only if owners decide to follow on with chemo o  As would influence choice of agent •  OSA à carboplatin •  Histiocytic sarcoma à lomustine
  24. Key  points •  Although osteosarcomas are the most commonly occurring primary bone tumours, if lesion is not in usual predilection site, then also consider: o  Histiocytic sarcomas – particularly in Bernese Mountain Dogs, Flat coated retrievers, Rottweilers & Golden Retrievers o  Secondary mets – esp from mammary/prostatic carcinomas and multiple myeloma •  Always take radiographs of (or CT scan) opposite limb as well ! o  Very helpful for comparison + evaluating patient suitability for surgery
  25. Julie, who initially saw Jerri Gawain Hammond, for imaging interpretation advice Jo Morris, for going over the case with me Everyone here, for listening J