L4: Mesenchymal Neoplasia (Beatty) Flashcards
Benign mesenchymal neoplasia ends in:
-oma
Ie. Fibroma, lipoma
Malignant mesenchymal neoplasia ends in:
-sarcoma
Ie. Osteosarcoma, Soft tissue sarcoma
How do mesenchymal tumors met?
Hematogenously (typically)
-usually go to LIV, SP first
Mesenchymal cells form:
Connect tissue, blood vessels, lymphatics
-originate in soft tissue, bone, and cartilage
Selected mesenchymal neoplasms
- lipoma/liposarcoma
- scar tissue/reactive fibroplasia
- equine sarcoid
- soft tissue sarcoma
- hemangiosarcoma
- synovial cell sarcoma
- osteosarcoma
Chars. Of lipoma
- common SC tumor in dog
- less commonly IM or infiltrative
- do NOT transform into liposarcomas*
- slides appear oily
- aspirated material may wash off fixative
- appearance: variable # of adipocytes and strung out stromal cells; small nuclei can be smushed to the side
- adipocytes can’t be differentiated from normal SC fat*
Chars. Of liposarcoma
- uncommon tumor in older dogs
- spindle-shaped cells w/ features of malignancy
- lipid rich background
- predilection for ventrum and extremities
- feel firmer than lipomas
Chars. Of scar tissue/reactive fibroplasia
- mesenchymal cells w/ variable atypia
- often inflamed
- histopath often needed to differentiate from neoplasia
Chars. Of Equine sarcoids
- common cutaneous tumor in horses
- char. By atypical mesenchymal cells
- Ddx: granulation tissue, sarcoid, fibrosarcoma
- assoc. with bovine papilloma virus*
- needs histopath for dx
Types of soft tissue sarcomas
- perivascular wall tumors
- fibrosarcoma
- myxosarcoma
- peripheral nerve sheath tumors
Chars. Of perivascular wall tumors
- formerly called “hemangiopericytoma”
- originates from vascular pericytes, myopericytes
- common mesenchymal tumor in dogs
- common on lateral surface of extremities
Cytologic char. Of perivascular wall tumors
- extremely cellular
- anaplastic mesenchymal cells w/ very wispy cytoplasm
- small punctate cytoplasmic vacuoles
- 1-2 prominent nucleoli per cell
- cells branch off capillaries
- multinucleated cells w/ peripheral nuclei (crown cells)
Chars. Of fibrosarcoma
- occur in older animals
- may be assoc. with injections in cats (rabies most common)
- firm, variable exfoliation
- absence of inflammation (center may be necrotic and inflamed)
- locally infiltrative and aggressive
- must get wide sx excision +/- radiation!
- slow to met usually
Cytologic chars. Of fibrosarcomas
- low to moderate # individually arranged cells
- spindle-shaped w/ malignancy chars. (Ie. Coarse chromatin, nucleolus larger than RBC, high N:C
- pink eosinophilic fibrillar matrix around cell clumps
- absence of inflamm.
Histopath of soft tissue sarcomas
- typically not differentiated
- graded on 1+ to 3+ scale based on differentiation, mitotic rate, and necrosis
- grade predictive of metastasis and possible local recurrence**
Chars. Of hemangiosarcoma
- older, large breeds
- sites: SP, LIV, R atrium, retroperitoneal space, bone, dermal
- assoc. with collapse, hemoabdomen, fragmentation hemolysis (shistocytes, keratocytes, ecchinocytes), thrombocytopenia, DIC
- endothelial cell (blood vessel) origin
Cytologic chars. Of hemangiosarcoma
- large atypical pleomorphic cells w/ pale blue cytoplasm with colorless punctate vacuoles
- variable exfoliation
- many samples hemodilute
Chars. Of synovial cell sarcoma
- CT neoplasm arising from cells in the synovial membrane
- sites: elbow, stifle, shoulder of large breeds
- difficult to distinguish b/w histiocytic sarcoma and SCS
- locally invasive, may cross the joint, 25% met
Cytologic chars. Of synovial cell sarcomas
- granular eosinophilic background (mucin)
- dual pop. Of anaplastic mesenchymal cells that are oval w/ eccentrically placed nuclei and spindle-shaped
- large angular, irregular nuclei
- mitotic figures
Which neoplasias have mucinous backgrounds on cytology?
Synovial cell sarcomas
Myxosarcomas
Chondrosarcomas
Histiocytic sarcoma
- neoplasm of joints
- common in Rottweiler, stifles
Synovial myxoma
- neoplasm of joint
- Dobermans, stifles
General chars. Of tumors of bone and cartilage
- may arise from any tissue in bone, mesenchymal cells of osseous or cartilaginous origin, or vascular or CT cells
- many malignant in dogs
- felines and equines may be benign
- includes osteomas and chondromas
Chars. Of osteosarcoma
- most common malignant bone tumor of the limbs
- looks similar to round cell tumor
- appendicular forms typically in giant or large breeds
- uncommon in cats
- sites: away from elbow, toward the knee
- rapid hematogenous spread
- 90% have mets by time of dx! (LU)
- ones on axial skeleton may be less aggressive and are more common in small dogs
- feline OS more common on femur and are less aggressive w/ reduced incidence of mets
Cytologic appearance of osteosarcoma
- looks like round cell tumor
- large oval to spindle shaped cells
- individually arranged
- variably distinct cytoplasmic borders
- eccentric nuclei*
- MNGCs
- dense amorphous pink material = osteoid
Ddx for lytic proliferative bone lesion
Osteosarcoma
Fungus
Multiple myeloma
General characteristics of mesenchymal neoplasms
- variable exfoliation
- cells individually arranged
- indistinct, wispy cytoplasmic borders
- spindle-shaped, fusiform, stellate cells
- nuclear features CAN be reliable indicator for most
- histopath can be needed for muscle and cartilagenous tumors (ie. Leiomyoma)
