Leukaemia and lymphadenopathy 2 Flashcards
What are the 2 forms of plasmacytomas?
Cutaneous and extramedullary
Describe cutaneous plasmacytomas
- Solid masses which may be single or multiple
- Usually benign, best prognosis
- Well demarcated, excision with good margins generally curative
Describe extramedullar plasmacytomas
- Solid tissue tumour
- Malignant
- Produce monoclonal immunoclobulins
- Solitary masses
- Cause amyloidosis
- Take over tissues
Which organs are commonly affected by extramedullary plasmacytomas?
- Arises most frequently in GIT
- Also trachea, spleen, kidney, uterus, CNS, elsewhere
How are extramedullary plasmacytomas diagnosed?
On serum/plasma
What are the effects of amyloidosis?
Deposition of abnormal proteins that cannot be broken down in the liver/kidney, leading to loss of function and atrophy of normal tissue
what are multiple myelomas?
Malignant tumour of plasma cells arising in the bone marrow
Describe the pathogenesis of multiple myelomas
- Secrete large amounts of Ig (hyperglobulinaemia, monoclonal gammopathy) and cytokines that activate osteoclasts
- Osteolysis leads to hypercalcaemia
- Highly proliferative
Describe the appearance of multiple myelomas
- Shotgun appearance lesions in bone
- Light chain proteinuria
- Possible anaemia
- Possible amyloidosis
- haemorrhages due to secondary platelet dysfunction
- Hyperviscosity syndrome
- Cytopaenias
What are the clinical signs of myeloid tumours generally caused by?
Loss of other cell lines
Outline myeloid dysplasias
- Rare
- Tumours starting in bone
Name histiocytic neoplasias
- Cutaneous histiocytoma
- Histiocytic sarcoma
Describe the typical presentation of a cutaneous histiocytoma
- Young dog
- Circular raised, alopecic nodule
- No damage to surrounding tissues
Outline the treatment for a cutaneous histiocytoma
- Often spontaneously regress
- Can be left, but excise if needed
Describe histiocytic sarcomas
Uncommon, malignant tumours of dendritic cells or macrophages
How may histiocytic sarcomas cause anaemia?
Sometimes cause haemophagocytic syndrome
Which breeds are predisposed to histiocytic sarcomas?
Rottweilers, Bernese Mountain dogs
Which form of histiocytic sarcomas is rapid and aggressive?
Disseminated form
Describe the cytological appearance of a histiocytic sarcoma
- Neoplastic cells are round cells with abundant grey-blue cytoplasm
- Multinucleation, prominent nucleoli, mitotic figures visible
- Hyperchromatic nuclei
Describe the gross appearance of a spleen with a haemophagocytic histiocytic sarcoma of macrophage origin
Diffuse splenomegaly with ill-defined mass formation
Where do mast cell proliferations typically develop?
Mostly cutaneous or subcutaneous, can occasionally develop in the spleen, liver, intestine or elsewhere
Outline the importance of KIT in the development of mast cell proliferations
- Mutations of the c-kit protooncogene that codes for KIT protein stem cell factor receptor may be responsible for the development or progression of mast cell tumours
- KIT expression is inversely related to the degree of differentiation of canine mast cell tumours
- Increased KIT = less differentiated tumour
Describe the appearance of mast cell proliferations
- Solitary or multicentric, dermal or subcutaneous, nodular or pedunculated
- May be erythematous and oedematous
Describe the behaviour of mast cell proliferations
Some benign, others malignant. Some may appear benign but behave malignantly