Histiocytic sarcoma or Osteosarcoma? That is the question

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  1. 1. Histiocytic sarcoma or osteosarcoma... That is the question
  2. 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 vets: radiographs (& referral) + tramadol + advised strict rest
  3. 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. 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. 5. Radiographs sent Ulna involvement - unusual
  6. 6. Radiographs sent No pulmonary metastatic nodules were seen on chest radiographs
  7. 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. 8. Test results / ndings 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. 9. CT thorax (lung window)
  10. 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. 11. Right elbow also showed aggressive lytic change, Centred especially on right medial humeral condyle. CT forelimbs (bone & soft tissue windows)
  12. 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. 13. Types of tumours that can aect bone in dogs Osteosarcoma Chondrosarcoma Fibrosarcoma Haemangiosarcoma Rhabdomyosarcoma Histiocytic sarcoma Metastatic tumors that may present clinically as bone tumors: Carcinomas Plasma cell myeloma
  14. 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. 15. Osteosarcomas Transformed malignant cell is the osteoblast Neoplastic cells often round/ovoid Cowell & Tyler cells from a canine osteosarcoma and not
  16. 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. 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. 18. Back to Jerri Histiocytic sarcoma? Osteosarcoma?
  19. 19. Jerris FNA slides - discussion Cytology can be rewarding but also confusing, especially to the unpractised eye Special cytochemical stains available o BCIP/NBTsolution 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. 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. 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. 22. Recommendations and owners 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 shes scheduled to come in week commencing 15 sept for a 5d course of radiotherapy (palliative intent)
  23. 23. Updates Owner has called on 2 occasions o Worried about Jerris lameness o Wondering if can XRT both forelimbs going to give it a go Jo also thinking of doing a repeat FNA (just for interests sake) o Definitive diagnosis more important only if owners decide to follow on with chemo o As would influence choice of agent OSA carboplatin Histiocytic sarcoma lomustine
  24. 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. 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