L5: Round Cell Neoplasms Flashcards
6 selected round cell neoplasms
- lymphoma
- plasma cell tumor
- histiocytic diseases (histiocytoma, histiocytosis, histiocytic sarcoma)
- TVT
- MCT
- Melanoma
Criteria of malignancy for round cell neoplasms
- features variable and not reliable
- high N:C ratio usually
- histopath recommended for grading/tissue architecture for MCT, lymphoma, and melanomas
Round cell neoplasia nomenclature
Benign: -cytoma
Malignant: -oma
How do round cell tumors usually met?
Lymphatic
General chars. Of round cell neoplasms
- readily exfoliate
- individualized cells and loose aggregates of many cells
- round or oval cells
- distinct cytoplasmic borders
Chars. Of lymphoma on FNA
-B vs. T can’t be definitively told
-large B cell lymphomas, canine LSA CAN be diagnosed
-cutaneous lymphoid lesions, feline and equine LSA usually need histopath
-T cell lymphoma usually worse than B
(Less easily targeted by chemo)
Substages of lymphoma
Substage b: p unwell at presentation
Substage a: p well at present
T cell rich B cell lymphoma
- type of lymphoma that horses and ferrets
- neoplastic B cells with large infiltrates of T cells
Size of large lymphocytes
3x or greater than RBC; bigger than neuts
How does leukemia and lymphoma spread and where do they start?
Leuk: centrifugal; starts in bone marrow usually
Lymph: centripetal; starts in lymphoid organ usually
How does leukemia and lymphoma spread and met?
Leuk: circulates in blood, may met to LN
Lymph: spreads to multiple lymphoid organs, may circulate in the blood; may met to bone marrow if advanced
Chars. Of Plasma cell tumor
- lymphoid neoplasm
- more common in dogs than cats
- extramedullary sites: digits, ears, oral cavity, GI, LIV, SP
- multiple myeloma form of plasma cell neoplasm of the bone marrow
- more likely to be aggressive in oral cavity or GIT
Cytologic appearance of plasma cell tumor
-dk. Blue cytoplasm
-perinuclear colorless area (Golgi zone)
-round, eccentric nucleus = classic sign
-pleomorphic nuclei
+/- binucleation and multinucleation
-anisokaryosis
4 diagnostic criteria of multiple myeloma:
1) serum monoclonal gomopathy
2) Bence jones proteins
3) >20% cells in bone marrow = plasma cells
4) punched out lytic lesions in scapula, vertebral body, etc.
Chars. Of histiocytic diseases
- part of the mononuclear phagocyte system (dendritic, macrophage-type cells)
- variable prognoses
- includes histiocytoma, histiocytosis, histiocytic sarcoma
Chars. Of histiocytoma
- benign cutaneous neoplasm
- young dogs
- pink, hairless
- usually on head or trunk
- will spontaneously regress via cell-mediated immunity T cell infiltrate
Cytologic chars. Of histioma
- cells have colorless cytoplasm
- “shplurted” cells (don’t exfoliate well)
Chars. Of histiocytic sarcoma
- more common in Bernese mountain dogs, rotties, retrievers
- arises at single site
- primary lesion sites: skin, SP, LN, LU, bone marrow, meninges, periarticular
- secondary sites: LIV, LU, hilar LN
- can be hemophagocytic
Chars. Of hemophagocytic histiocytic sarcoma
- arises in bone marrow or SP
- generalized splenomegaly, mottling on US
- assoc. with concurrent anemia, thrombocytopenia, hypoalbuminemia, hypocholesterolemia
Chars. Of malignany histiocytosis
- aggressive histiocytic neoplasm that arises at multiple sites simultaneously
- aka disseminated HS
- Bernese Mountain dogs most common
Chars. Of transmissible venereal tumor
- transmissible
- histiocyte lineage
- typical locations: nasal cavity, external genitalia mm
- tumors can become large and ulcerate
- uncommonly met to regional LN
- 57-59 chromosomes/cell
- responsive to chemo
- more common in the Caribbean
Cytologic chars. Of TVT
- round cells
- pale basophilic cytoplasm w/ characteristic clear punctate vacuoles
- central to eccentric nucleus
- coarse chromatin
- 1+ prominent nucleoli
- moderate to high N:C
- mature lesions may contain small tumor infiltrating lymphs
- high mitotic rate
Chars. Of mast cell tumors
- common cutaneous/SC tumor in dogs (boxers, bostons, bulldogs, pugs, labs, goldens, shar peis, terriers, weimers)
- less common in felines, equines
- graded on 1+ to 3+ scale based on histopath
- nailbed, scrotal, mucocutaneous sites have poorer prognosis
- met to regional LN/other organs
- young animals can have multiple lesions that may spontaneously regress
- visceral form –> systemic mastocytosis and affects GIT, SP, LIV and is more common in cats; usually see in peripheral circulation
Cytologic chars. Of MCT
- round cells w/ variable # of purple granules
- granules contain HA, heparin, TNF, proteases, lipid mediators, proteases, and other cytokines
- usually can’t see granules on Diff Quick
- eosinophilic inflammation
- reactive fibroblasts
- collagen lysis
Chars. Of melanocytic neoplasms
- round cell neoplasm that actually has neuroectodermal origin
- more common in dogs/horses
- gray horses: base of tail, perineum, lips, eyelids
- Dogs: more aggressive if on digit or oral cavity; less aggressive if on trunk
Cytologic appearance of melanocytic neoplasms
- variable appearance in regards to cellular shape and pigmentation
- cells fragile so often see granules in the background
- can look both epithelial and like a round cell
