1. Practical Oncology Round Cell Tumors
Wendy Blount, DVM

2. Round Cell Tumors
Lymphoma
Mast Cell Tumor
Plasma Cell Tumor
Extramedullary Plasmacytoma
Multiple myeloma
Histiocytic Disease
Transmissible Venereal Tumor

3. Diagnosis
Generally diagnosed with cytology, as they exfoliate well
May need histopathology if anaplastic
Immunohistochemistry if markedly anaplastic
Gives information about prognosis

4. Plasmacytoma
Round, button like tumors on the skin and mucous membranes
Technically malignant
Usually behave benignly if extramedullary
Surgery is curative if borders clean
Radiation curative if not resectable

5. Plasmacytoma

6. Plasmacytoma

7. Multiple Myeloma
Malignant plasma cells proliferate in bone marrow and are released into circulation
Malignant cells found in
Skeleton
Lymph nodes and spleen
Kidney and liver
Produce large amounts of a specific Ig or part of an Ig
Mono or biclonal gammopathy
Bence Jones protein is the light chain
heavy chain or paraprotein also possible

8. Multiple Myeloma Clinical Signs Lethargy, anorexia weight loss
Lameness + pathologic fracture
PU-PD
Hyperesthesia
Hyperviscosity Syndrome
Immunosuppression – cytopenias & inhibition of humoral immunity
anemia more common than leukopenia or thrombocytopenia
Hypercalcemia
Azotemia - hypercalcemia, renal infiltration, hyperviscosity

9. Multiple Myeloma Hyperviscosity syndrome (TP >10) Heart failure
Reduced flow through small vessels
plasma volume expansion
volume overload
Myocardial hypoxia
Neurologic signs due to hypoxia
Seizures, disorientation, ataxia
Peripheral neuropathy

10. Multiple Myeloma Hyperviscosity syndrome (TP >10)
Bleeding diathesis
Capillary damage from hypoxemia
Inflammatory coagulopathy
Epistaxis, gingival bleeding
Retinal detachment, hyphema, secondary glaucoma, blindness
Renal ischemia

11. Multiple Myeloma Diagnosis – 2 of 5
Paraproteinemia (monoclonal gammopathy)
Serum protein electrophoresis
Also caused by rickettsial disease
Osteolytic bone lesions (punched out)
Generalized osteopenia
Pathologic fractures
More common in dogs than cats
Radiograph spine, ribs and limbs
Biopsy lytic lesion and take bone marrow sample

12. Multiple Myeloma Diagnosis – 2 of 5
>20% plasma cells in the bone marrow
DDx – atopy, rickettsial infection, FIP, Leishmania spp, heartworm disease
Bence Jones proteinuria
Not detected on urine dipstick
Infiltration of liver, spleen and skin with plasma cells (cats)

13. Multiple Myeloma Treatment Treat hyperviscosity diuresis
Whole blood or platelet rich plasma for bleeding diathesis
Treat hypercalcemia (pamidronate)
Plate pathologic fractures
Treat secondary infection
Treat renal failure
Chemotherapy melphalan and prednisone, with or without 1 dose cyclophosphamide

14. Multiple Myeloma Rescue Therapy – 3 week cycle
Week 1 – doxorubicin 30 mg/m2 IV
Start prednisone 1 mg/kg PO SID
Week 2, 3 – vincristine 0.7 mg/m2
Wean off prednisone of possible

15. Multiple Myeloma x

16. Multiple Myeloma Prognosis Short term prognosis is good
median survival 540 days (2.5 years) with treatment
Long term prognosis poor, as recurrence is expected
Bone pain and pathologic fractures main cause of morbidity and mortality
Negative prognostic indicators:
Hypercalcemia
Bence Jones proteinuria
Extensive bony lysis

17. Histiocytic Disease
Histiocytoma
Cutaneous histiocytosis
Systemic histiocytosis
Localized histiocytic sarcoma
Malignant histiocytosis
aka disseminated histiocytic sarcoma

18. Histiocytoma
Single alopecic button like mass
Usually young dogs
Usually spontaneously regresses
Can take 2-3 months
Aspiration can induce regression
If large, may need to be resected
If >2 yrs old, remove for histopath
Rare in cats
Cytology – small lymphocytes may be more numerous than histiocytes

19. Histiocytoma

20. Cutaneous Histiocytosis (dogs)
Single mass or multiple masses
May regress spontaneously
May wax and wane over years, requiring multiple surgeries or immunosuppressive therapy
Prednisone 2 mg/kg PO SID, and taper as signs regress over 2-3 months
Cyclosporine 5 mg/kg PO SID-BID, taper
Leflunomide 2-4 mg/kg PO SID
Goal is trough level 20 mcg/ml, taper
Side effect vomiting

21. Systemic Histiocytosis
Familial in Bernese Mountain Dog
Slowly progressive disease
Cutaneous masses
Sometimes other organs are affected
Localized histiocytic sarcoma
Also retrievers and Rottweilers
Nodules occur around and infiltrate joints

22. Malignant Histiocytosis
Multi-system, rapidly progressive disease
Bernese Mountain dogs, retrievers, Rottweilers
Histiocytic infiltration of spleen, lymph nodes, lung, bone marrow, skin
Usually leads to death in weeks
Clinical signs
Weight loss, lethargy, anorexia
Coughing, dyspnea
Seizures, weakness, lameness
No effective treatment

23. TVT
The only known naturally occurring tumor that can be transplanted as an allograft
Transmitted by transplantation of cells onto abraded mucous membranes
During breeding
Nose to butt contact
In the nose, on the perineum, or on/in the reproductive tract
Begins as hyperemic papules
Progresses to multilobulated, ulcerated, bleeding mass

24. TVT If untreated, can metastasize
Eye, skin, lips, oral and nasal cavities
Regional lymph nodes
Lungs, liver, brain
Abnormal karyotype with 59 chromosomes
Dogs normally have 78
May occasionally spontaneously regress
Usually recur if surgically removed

25. TVT Treatment Vincristine 0.7 mg/m2 IV weekly
Continue 2-3 weeks past resolution of disease
Usually 3-5 injections are required
If no response, doxorubicin 30 mg/m2 IV q3 weeks x 3 treatments
Radiation is also effective, but often reserved for those that do not respond to chemotherapy
Spay-neuter and do not allow to roam

26. TVT

27. TVT

28. TVT

29. TVT

30. Round Cell Tumor Cytology
Covered Lymphoid Cells
Histiocyte – larger than lymphoblast
Round to indented nucleus
Scant to Moderate pale cytoplasm
Mast Cell – histiocyte w/ purple granules
TVT – histiocyte with clear vacuoles
Plasma Cells
Dark blue cytoplasm with central pallor
Perinuclear clear zone (Golgi zone)
Eccentric nucleus

31. Cytology
Rottweiler, sick with enlarged lymph nodes, spleen and liver – LN cytology
Dx – large cell lymphoma

32. Cytology
Button like alopecic skin mass

33. Cytology
Button like alopecic skin mass
Dx - Plasmacytoma

34. Cytology
Button like alopecic tumor
Dx – mast cell tumor

35. x

36. Cytology
Golden Retriever, sick with enlarged lymph nodes, spleen and liver
Dx – malignant histiocytosis

37. Cytology
Recurring button like alopecic masses
Dx – cutaneous histiocytosis

38. Cytology alopecic tumor protruding from the naris, bleeds when bumped
Dx – TVT

39. Cytology
Infiltrative plaque-like skin masses
Dx – Multiple Myeloma