L5: Round Cell Neoplasms

Question 1

6 selected round cell neoplasms

Answer 1

• lymphoma
• plasma cell tumor
• histiocytic diseases (histiocytoma, histiocytosis, histiocytic sarcoma)
• TVT
• MCT
• Melanoma

Question 2

Criteria of malignancy for round cell neoplasms

Answer 2

• features variable and not reliable
• high N:C ratio usually
• histopath recommended for grading/tissue architecture for MCT, lymphoma, and melanomas

Question 3

Round cell neoplasia nomenclature

Answer 3

Benign: -cytoma
Malignant: -oma

Question 4

How do round cell tumors usually met?

Answer 4

Lymphatic

Question 5

General chars. Of round cell neoplasms

Answer 5

• readily exfoliate
• individualized cells and loose aggregates of many cells
• round or oval cells
• distinct cytoplasmic borders

Question 6

Chars. Of lymphoma on FNA

Answer 6

-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)

Question 7

Substages of lymphoma

Answer 7

Substage b: p unwell at presentation

Substage a: p well at present

Question 8

T cell rich B cell lymphoma

Answer 8

• type of lymphoma that horses and ferrets

- neoplastic B cells with large infiltrates of T cells

Question 9

Size of large lymphocytes

Answer 9

3x or greater than RBC; bigger than neuts

Question 10

How does leukemia and lymphoma spread and where do they start?

Answer 10

Leuk: centrifugal; starts in bone marrow usually
Lymph: centripetal; starts in lymphoid organ usually

Question 11

How does leukemia and lymphoma spread and met?

Answer 11

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

Question 12

Chars. Of Plasma cell tumor

Answer 12

• 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

Question 13

Cytologic appearance of plasma cell tumor

Answer 13

-dk. Blue cytoplasm
-perinuclear colorless area (Golgi zone)
-round, eccentric nucleus = classic sign
-pleomorphic nuclei
+/- binucleation and multinucleation
-anisokaryosis

Question 14

4 diagnostic criteria of multiple myeloma:

Answer 14

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.

Question 15

Chars. Of histiocytic diseases

Answer 15

• part of the mononuclear phagocyte system (dendritic, macrophage-type cells)
• variable prognoses
• includes histiocytoma, histiocytosis, histiocytic sarcoma

Question 16

Chars. Of histiocytoma

Answer 16

• benign cutaneous neoplasm
• young dogs
• pink, hairless
• usually on head or trunk
• will spontaneously regress via cell-mediated immunity T cell infiltrate

Question 17

Cytologic chars. Of histioma

Answer 17

• cells have colorless cytoplasm

- “shplurted” cells (don’t exfoliate well)

Question 18

Chars. Of histiocytic sarcoma

Answer 18

• 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

Question 19

Chars. Of hemophagocytic histiocytic sarcoma

Answer 19

• arises in bone marrow or SP
• generalized splenomegaly, mottling on US
• assoc. with concurrent anemia, thrombocytopenia, hypoalbuminemia, hypocholesterolemia

Question 20

Chars. Of malignany histiocytosis

Answer 20

• aggressive histiocytic neoplasm that arises at multiple sites simultaneously
• aka disseminated HS
• Bernese Mountain dogs most common

Question 21

Chars. Of transmissible venereal tumor

Answer 21

• 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

Question 22

Cytologic chars. Of TVT

Answer 22

• 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

Question 23

Chars. Of mast cell tumors

Answer 23

• 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

Question 24

Cytologic chars. Of MCT

Answer 24

• 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

Question 25

Chars. Of melanocytic neoplasms

Answer 25

• 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

Question 26

Cytologic appearance of melanocytic neoplasms

Answer 26

• 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