Mesenchymal Neoplasms

Question 1

What are the characteristics of mesenchymal cells?

Answer 1

variable exfoliation

indistinct, wispy cytoplasmic borders

spindle shaped, fusiform, stellate cells

cell individually arranged

more oval shaped nuclei than epithelial cells

Question 2

Tissue of origin?

Benign or malignant?

Tumor type?

Answer 2

mesenchymal

malignant

Leiomyosarcoma

Question 3

Which mesenchymal tumors may need histopathology to determine biological behavior?

Answer 3

Muscle tumors= Leiomyoma/sarcoma & myxoma/sarcoma

Cartilagenous tumors= chondroma/sarcoma

Question 4

Via which route do mesenchymal tumors typically metastasize?

Answer 4

hematogenous routes

Question 5

Describe the characteristics of malignancy in this sample? What general classification would this tumor be?

Answer 5

Anisokaryosis, mitotic figures, open chromatin, multiple nucleoli

Sarcoma

Question 6

Tumor type?

Benign or malignant?

Answer 6

mesenchymal- lipoma

benign

Question 7

An owner reports that she thinks a previously diagnosed lipoma has become cancerous and spread to the other areas of the dog’s ventrum. Is this a possibility?

Answer 7

No, liposarcomas do not arise from malignant transformations of lipomas

Question 8

If you suspect that around an surgery scar there is an area of scar tissue/reactive fibroplasia, what should you do to confirm?

Answer 8

Histopathology

Question 9

What is the most common cutaneous tumor of horses?

Answer 9

sarcoid

Question 10

A firm, SQ mass is palpated on the hind end of a horse. On cytology of the mass, it appears mesenchymal. What are the top three differentials? How would you confirm?

Answer 10

sarcoid

Granulation tissue

fibroma

Perform histopathology to confirm tumor and biologic behavior

Question 11

What four ST sarcomas do we typically all treat the same?

Answer 11

perivascular wall tumor

fibrosarcoma

myxosarcoma

peripheral nerve sheath tumor

Question 12

Describe the characteristics of perivascular wall tumors.

Answer 12

High exfoliation

very vascular

multinucleated cells with peripheral nuclei (crown cells)***

very wispy cytoplasm and anaplastic cells

small punctate vacuoles

1-2 nucleoli

Question 13

Tumor type?

Answer 13

mesenchymal, perivascular wall tumor

Question 14

Tumor type

Answer 14

Soft tissue sarcoma

Question 15

Tumor type?

Answer 15

ST sarcoma

Question 16

Where are perivascular wall tumors commonly found?

Answer 16

on the extremities, especially the lateral surface

Question 17

When is a biopsy for a mass from a vaccination warranted?

Answer 17

present 3 months after vaccination

>2 cm in diameter

increasing in size 1 month after vaccination

Question 18

What are the characteristics of fibrosarcomas?

Answer 18

low exfoliation

individual arranged cells

pink eosinophilic matrix (collagen)

absence of inflammation

Question 19

What comparative measure can be used to determine if a nucleus is enlarged?

Answer 19

compare to the size of a RBC

Question 20

T/F Fibrosarcomas metastasize quickly.

Answer 20

FALSE

Question 21

What are the characteristics of hemangiosarcomas on cytology? In which sites do we typically see these tumors?

Answer 21

variable exfoliation (hemodilute often)

large, typical cells

pale blue cytoplasm with clear vacuoles

Sites: spleen, liver, R-atrium, retroperitoneal space, bone, dermal (derived from mets most often)

Question 22

Tumor type?

Benign or malignant?

Answer 22

Mesenchymal, hemangiosarcoma

[pale blue cytoplasm, cytoplasmic vacoules]

malignant

Question 23

What are the site predilections for synovial cell sarcomas?

Answer 23

elbow, stifle, shoulder

Question 24

Which tumor is hard to differentiate from synovial cell sarcoma on histo and cyto? (special stains needed)

Answer 24

Histiocytic sarcoma

Question 25

synovial cell sarcomas are locally invasive and metastasize in 25% of reported cases. T/F

Answer 25

True

Question 26

What are the features of synovial cell sarcomas?

Answer 26

granular eosinophilic background (mucin)

Dual population of anaplastic cells:

1. oval with eccentrically placed nuclei
2. spindle shaped

Question 27

Name the three types of tumors that can affect the joints? What are their site/breed predilections?

Answer 27

1. Synovial cell sarcoma- elbow, stifle, shoulder
2. Histiocytic sarcoma- stifle, Rottweiler
3. Synovial myxoma-stifle, Doberman

Question 28

Tumor type?

Answer 28

Synovial cell tumor

(eosinophilic background, two aplastic cell populations)

Question 29

What are the characteristics of osteosarcomas?

Answer 29

May appear as round cell tumors

Eccentric nuclei

Large, oval - spindle shaped cells (individual)

Dense, amorphous pink material (osteoid***)

variable, distinct cytoplasmic borders

muti-nucleated giant cells (osteoclasts)

Question 30

What is the most common site for osteosarcoma in the cat?

Answer 30

femur

Question 31

What are the sites common for osteosarcoma in a dog?

Answer 31

metaphyseal region

“away from the elbow, towards the knee”

• proximal humerus
• distal radius & ulna
• proximal tibia
• distal femur

Question 32

Tumor type?

Answer 32

Osteosarcoma

(osteoid in the cells pink granular material is the give away)

Question 33

Does osteosarcoma have a better prognosis in the cat or dog? Axial or appendicular skeleton?

Answer 33

cat

axial skeleton

Question 34

What is the first diagnostic that should be performed on a dog with suspected osteosarcoma on the appendicular skeleton?

Answer 34

thoracic radiographs