16a - Hematopoietic Neoplasia Cont. Flashcards
What are 3 types of plasma cell tumours?
- Cutaneous plasmacytoma
- Extramedullary (and non-cutaneous) plasmacytoma
- Multiple myeloma (plasma cell myeloma)
Cutaneous plasmacytoma
- Solid tumour of plasma cell originating in skin
- Mature animals
o Most frequently dogs
o Rarely cats - Usually solitary benign lesion=surgical excision is often CURATIVE
Cutaneous plasmacytoma microscopically
- UNIFORM population of well-differentiated plasma cells OR
- Marked anisocytosis and anisokaryosis (anaplastic plasmacytoma)
Extramedullary plasmacytoma
- Solid tumour of plasma cell origin arising from sites OTHER THAN bone marrow and skin
- RARE: More often in dogs (Cocker Spaniels=predisposed)
- Arise in GI tract, but may occur in trachea, spleen, kidney, uterus, etc.
- *more aggressive than cutaneous plasmacytoma with occasional METASTASIS to LYMPH NODES
Multiple myeloma (plasma cell myeloma)
- Relatively UNCOMMON in domestic animals
o Most often in dogs and cats - *malignant tumours of plasma cell origin arise WITHIN BONE MARROW
o Neoplastic cells secret Ig leading to hypergammaglobulinemia
How is hypergammaglobulinemia detected?
- Serum protein electrophoresis as a monoclonal spike in globulin fraction
What can hypergammaglobulinemia lead to
- Hyper viscosity syndrome
- Light-chain (Bence-Jones) proteinuria
Hyperviscosity syndrome from hypergammaglobulinemia
- Sludging of blood cells
- Hypotension
- Shock
Light chain (Bence-Jones) proteinuria
- Proteins are FREE Ig LIGHT CHAINS
o Pass through glomerulus into urine=detected using electrophoresis and immunoprecipitation
What plasma cell tumours look like GROSSLY?
- Sections of bone exhibit:
o Multiple dark-red soft/gelatinous tissue nodules filling areas of bone resorption/lysis - 2/3 of dog cases have radiographic ‘punched out’ lesion in skeleton
- *found in haematopoietically active bone, MOST common in VERTEBRAE
- May have hypercalcemia
What do plasma cell tumours look like HISTOLOGICALLY?
- Masses composed of sheets of neoplastic plasma cells in bone marrow
What are the clinical signs of plasma cell tumours?
- Lameness
- Ill-defined pain
- Lethargy
- *paraplegia can occur due to direct spinal cord compression by protrusion of masses into vertebral canal or secondary to pathological vertebral fracture
- *SLOW PROGRESSIVE
- *neoplastic cells may metastasize to spleen, liver, lymph nodes and kidneys
Myeloproliferative disease: ‘definition’
- Neoplastic transformation of one or more bone marrow cell lines
o Granulocytes
o Erythrocytes
o Megakaryocytes
o Monocytes
Myeloproliferative disease: 4 types
- Myeloid leukemia
- Myelodysplastic syndrome
- Histiocytic neoplasia
- Mast cell tumours (often not included in myeloproliferative disease)
Myeloid leukemia (clinical pathology) origins (4)
- Erythroid
- Granulocytic
- Monocytic
- Megakaryocytic
Myelodysplastic syndrome (clinical pathology)
- Group of myeloid proliferative diseases characterized by ineffective hematopoiesis
- *rare in Vet med: most often seen in FeLV-infected cats
Histiocytic neoplasia/proliferative diseases
- Most commonly in DOGS
o Wide range of disorders which vary in clinical behaviour
What are the histiocytic proliferative disorders seen in dogs? (3)
- Cutaneous histiocytoma
- Canine reactive histiocytosis
- Histiocytic sarcoma and disseminated histiocytic sarcoma
Canine reactive histiocytosis
- Limited to skin (cutaneous) OR simultaneously affects skin and other organs (systemic histiocytosis)
- *immunoregulatory disorder (rather than true neoplasia)
o Lesions respond to immunosuppressive therapy
What is the cell of origin in canine reactive histiocytosis?
- Activated dermal/interstitial dendritic cell (antigen presenting cell)
How is canine reactive histiocytosis characterized?
- Multifocal skin masses which wax and wane
Bernese Mountain dogs are predisposed to systemic form of canine reactive histiocytosis which involves
- Skin
- Peripheral lymph nodes
- Ocular/nasal mucosa
- Lungs
- Liver
- Spleen
Histiocytic sarcoma and disseminated histiocytic sarcoma
- RARE MALIGNANT tumours of histiocytic origin
- Most often in DOGS
- Solitary nodules OR multiple lesion that rapidly disseminate
- *poor prognosis
- *responds poorly to routine chemotherapy
Which breeds are more prone to histiocytic sarcoma and disseminated histiocytic sarcoma?
- Bernese Mountain dogs
- Rottweilers
- Flat-coated Retrievers
Where do solitary nodules of histiocytic sarcoma often arise in?
- Subsynovium of the joints OR in subcutis
- Other primary sites include: spleen, lymph nodes, etc.
Disseminated histiocytic sarcoma
- Aggressive multisystemic disease
- Characterized by presence of multiple tumour masses in several organ systems
What are the primary sites of disseminated histiocytic sarcoma?
- Spleen
- Lung
- Bone marrow
- Lymph nodes
- Skin
- subcutis
What are masses of histiocytic sarcoma composed of?
- Atypical histiocytes
- May arise from dendritic cells OR less often macrophages
o If from macrophages: may be avidly hemophagocytic causing rapidly progressive ANEMIA
What are 2 types of mast cell tumours?
- Cutaneous mast cell tumours
- Systemic mastocytosis/visceral mast cell tumours
Systemic mastocytosis/visceral mast cell tumours
- Primarily affects the hematopoietic system, especially the SPLEEN
- Most commonly occurs in CATS
What does systemic mastocytosis/visceral mast cell tumours look like grossly?
- Splenomegaly (diffuse or nodular)
- intestine and liver may be affected
What does systemic mastocytosis/visceral mast cell tumours look like microscopically?
- Effacement of splenic architecture by DENSE sheets of mast cells
- *ID mast cells using toludine blue staining
Secondary neoplasia of bone marrow
- Result of metastasis of NON-marrow origin neoplastic cells to the bone marrow
What is myelophthis?
- Replacement of hematopoietic tissue within the bone marrow by ABNORMAL TISSUE
o Usually replaced by fibrous tissue (=myelofibrosis) OR malignant cells
o May be reflected in peripheral blood as PANCYTOPENIA
