Practical OncologyRound Cell Tumors

Wendy Blount, DVM

Round Cell Tumors

• Lymphoma• Mast Cell Tumor• Plasma Cell Tumor

• Extramedullary Plasmacytoma• Multiple myeloma

• Histiocytic Disease• Transmissible Venereal Tumor

Diagnosis

• Generally diagnosed with cytology, as they exfoliate well

• May need histopathology if anaplastic

• Immunohistochemistry if markedly anaplastic• Gives information about

prognosis

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

Plasmacytoma

Plasmacytoma

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

Multiple MyelomaClinical 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

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

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

Multiple Myeloma

Diagnosis – 2 of 51. Paraproteinemia (monoclonal gammopathy)

• Serum protein electrophoresis • Also caused by rickettsial disease

2. 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

Multiple Myeloma

Diagnosis – 2 of 53. >20% plasma cells in the bone marrow

• DDx – atopy, rickettsial infection, FIP, Leishmania spp, heartworm disease

4. Bence Jones proteinuria• Not detected on urine dipstick

5. Infiltration of liver, spleen and skin with plasma cells (cats)

Multiple MyelomaTreatment• 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

Multiple MyelomaRescue 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

Multiple Myeloma

x

x

Multiple MyelomaPrognosis• 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

Histiocytic Disease

• Histiocytoma• Cutaneous histiocytosis• Systemic histiocytosis• Localized histiocytic sarcoma• Malignant histiocytosis

• aka disseminated histiocytic sarcoma

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

Histiocytoma

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

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

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

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

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

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

TVT

TVT

TVT

TVT

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

Cytology• Rottweiler, sick with enlarged lymph nodes,

spleen and liver – LN cytology• Dx – large cell lymphoma

Cytology

• Button like alopecic skin mass

Cytology

• Button like alopecic skin mass• Dx - Plasmacytoma

Cytology• Button like alopecic tumor• Dx – mast cell tumor

xx

Cytology• Golden Retriever, sick with enlarged lymph

nodes, spleen and liver• Dx – malignant histiocytosis

Cytology• Recurring button like alopecic masses• Dx – cutaneous histiocytosis

Cytology• alopecic tumor protruding from the naris,

bleeds when bumped• Dx – TVT

Cytology

• Infiltrative plaque-like skin masses• Dx – Multiple Myeloma