Practical OncologySoft Tissue SarcomasPractical OncologySoft Tissue Sarcomas

Wendy Blount, DVMWendy Blount, DVM

Soft Tissue Sarcomas• Locally invasive, but slow to metastasize• Fibrosarcoma (FSA)• Hemangiopericytoma (HPA)• Nerve sheath tumor, Schwannoma• Leiomyosarcoma (LMSA)• Spindle cell tumor• Liposarcoma (LPSA)• Different from infiltrative lipoma

• Myxosarcoma (MXSA)• Pleomorphic Undifferentiated Sarcoma

(PUS)• Aka malignant fibrous histiocytoma

(MFHA)

Soft Tissue Sarcomas• A few behave differently – not included

here• Hemangiosarcoma (HSA)• Lymphangiosarcoma• Rhabdomyosarcoma • Soft tissue osteosarcoma• Synovial cell sarcoma

Soft Tissue Sarcomas• Often extend beyond the visible mass• Microscopic tendrils

• know what you have before you exciseFNA all masses except SGA prior to excision• Send out for cytologic evaluation if necessary• Not enough experience• Not enough time• Can be difficult to distinguish from

fibroplasia, especially if inflammatory• Send stained and unstained – Giemsa stain

is superior for some features• Take a quick look to make sure you have

adequate cells other then RBC

Diagnosis• Often cytological diagnosis is “sarcoma”• May need histopathology for definitive

diagnosis• Excision biopsy (“en bloc” excision) is best for

diagnosis• If unresectable, may need to get incisional

biopsy• Best excision for large mass is done after CT

scan• If dirty margins, re-excise or radiation therapy

(if histopath indicates radiation)

Cytology

Cytology

• Wispy cytoplasm with streaming tails

Cytology

• Wispy cytoplasm with streaming tails• Occasional binucleate cell• Round to oval nuclei, inconspicuous nucleoli

Kristina Lemm – Houston TXShawn Penn – Lufkin TX

Cytology

• Wispy cytoplasm with streaming tails• Occasional binucleate cell• Round to oval nuclei, inconspicuous nucleoli

Cytology

• Wispy cytoplasm with streaming tails• Occasional binucleate cell• Round to oval nuclei, inconspicuous nucleoli• Cells in whorls, rare mitotic figures

Hemangiopericytoma

Cytology

Cytology

• Blunt ended nuclei, indistinct cell borders• Parallel alignment

Cytology

• Blunt ended nuclei, indistinct cell borders• Parallel alignment• Variation in cell and nucleus size

Cytology

• Blunt ended nuclei, indistinct cell borders• Parallel alignment• Variation in cell and nucleus size• Intranuclear inclusions

Leiomyosarcoma

Cytology

• Spindle shaped cells with minimal cytoplasm• Oval nuclei

Cytology

• Spindle shaped cells with minimal cytoplasm• Oval nuclei• Characteristics of malignancy

Fibrosarcoma

Cytology

Anaplastic Sarcoma

Cytology

Fibroma

Cytology

Cytology

Cytology

• Individual polyhedral cells with basophilic foamy cytoplasm

• Round to oval nuclei with prominent nucleoli

Cytology

• Individual polyhedral cells with basophilic foamy cytoplasm

• Round to oval nuclei with prominent nucleoli• Characteristics of malignancy

Liposarcoma

Cytology

• Non-staining, large ballooning cytoplasm• Collapsed cells with scan, lacy cytoplasm• Peripherally compressed nuclei

Lipoma or Infiltrative LipomaWell differentiated liposarcoma

Cytology

• Well differentiated fusiform & stellate cells

Cytology

• Well differentiated fusiform & stellate cells• Low cellularity with granular background

Cytology

• Well differentiated fusiform & stellate cells• Low cellularity with granular background• Occasional multinucleate cells• Mucin stains with Alcian blue stain

Myxosarcoma

Cytology

• Large multinucleate cells• Spindle/mesenchymal cells

Cytology

• Large multinucleate cells• Spindle/mesenchymal cells• Histiocyte-like round cells

Cytology

• Large multinucleate cells• Spindle/mesenchymal cells• Histiocyte-like round cells

Cytology

• Large multinucleate cells• Spindle/mesenchymal cells• Histiocyte-like round cells

Malignant Fibrous HistiocytomaPleomorphic Undifferentiated Sarcoma

Surgery• The mainstay of treatment for STSA• 3 cm lateral borders to visible mass• 1 fascia layer deep to visible mass• May appear to be encapsulated, but are not• Pseudocapsule made up of tumor cells• Still respect the border rules• “shelling out” results in recurrence

Radiation• If histopath indicates likely radiation

responsiveness• STSA not terribly radiation responsive

unless high MI• 20-30% response rate for gross disease• Results in long disease free interval when

post-surgical disease is microscopic• 4-5 years

• For tumors that can not be adequately re-excised• Taking more tissue not possible• Dirty borders after re-excision

Radiation• For tumors that are too large for “en bloc”

excision• Neoadjuvant therapy• Palliative therapy• Shrink tumor• Pain control

• When margins are “clean but close”• When concurrent condition precludes

anesthesia or surgery• Coagulopathy (VWDz, hemophilia)• Renal failure• Radiation may not be better, as it

requires multiple sedations

Radiation• For limb sparing tumor treatment when post-

amputation mobility difficulties expected• Response rate for radiation alone is poor

when compared to radiation + surgery• When you have hemangiopericytoma

Chemotherapy• STSA tend to be chemotherapy unresponsive

Prognosis• Local control is usually curative

• Staging is a low yield procedure, but indicated prior to starting extensive or expensive treatment • 3 views thoracic radiographs• Aspirate draining lymph nodes• (maybe abdominal US)

Prognosis• Local control is usually curative

• Staging is a low yield procedure, but indicated prior to starting extensive or expensive treatment • 3 views thoracic radiographs• Aspirate draining lymph nodes• (maybe abdominal US)

• Feline Sarcoma • Vaccine Associated Sarcoma (VAS)• Vaccine Associated Fibrosarcoma• Vaxosarcoma• Feline Injection Site Sarcoma

Emerged in the mid 1980’s

FISS Update

Usually a fibrosarcoma but can also be• PUS• Rhabdomyosarcoma• Mast cell tumor• Soft tissue osteosarcoma• Liposarcoma• Chondrosarcoma• Undifferentiated sarcoma

FISS Update

Relationship between FISS and chronic inflammatory responses following

• trauma or injections, including vaccination• some long-acting medications• even foreign materials such as suture and

microchips

Incidence varies widely between 1 per 1000 and 1 per 16,000 vaccinated cats.

FISS Update

• In cats younger than typical fibrosarcoma• Adjuvant and foreign bodies found within the

tumors• Site specific, correlating with common

injection sites• More aggressive behavior than the typical

fibrosarcoma• Some but not all are associated with feline

sarcoma virus (FeSV) infection

FISS Update

• Especially FeLV and rabies vaccines• When local laws began requiring rabies vaccination in cats,

incidence of FISS increased– FeLV is deadly and infects cats at 1-2% of well cats– Rabies is rare but is deadly to people

• THEORY– More appropriate extended feline vaccination protocols should

help– Vaccination annually with Purevax should be better than

triennially with an adjuvanted vaccine

Merial Purevax has been out for more than 10 years

FISS Update

• Virbac Pharmacovigilance project (Europe)– Adverse event reports 2000-2009– McGahie, 2012 (WSAVA)– FISS has a possible relationship with recombinant

subunit FeLV vaccine as well– FISS rate 1 per 500,000 vaccinations– No such relationship found for the Purevax rabies

vaccine

FISS Update

Diagnosis• Post-vaccination granulomas are common• If they fail to resolve within 3-4 weeks, if they

grow at all after the first week, or if they are larger than 2 cm, they should be removed for histopath– Treated like other soft tissue sarcomas at this

point– 3 cm borders– One fascia layer deep

FISS Update

Treatment• If FISS is confirmed, treatment should be

prompt and aggressive• Consider referral for more surgery– CT scan prior to surgery– Wide, wide margins

• Possible radiation and/or chemo depending on tumor site and histopath report

• Neoadjuvant therapy for large masses

FISS Update

Prognosis• Median survival variable, but can be more than 2 years

with surgery alone (average age 6 years)• Almost 4 years survival with surgery and radiation• Prognosis is worse if bone is invaded and the tumor can

not be removed by bilateral trapezius muscle excision• Distant metastasis is rare, but it makes prognosis worse• 84% of those treated with neoadjuvant epirubicin were

alive at 6 years– Less aggressive tumors were selected for therapy– 10% died of chemo induced renal failure

FISS Update

FISS Client Handout

FISS Update

AcknowledgementsPhilip J. Bergman, DVM, MS, PhD, DACVIM (Oncology)VIN Consultant, CMOfficer BrightHeart Vet Centers Louis-Philippe de Lorimier, DVM, ACVIM (Oncology)VIN Consultant, Univ Ill Urbana-Champaign

Karri A. Meleo, DVM, ACVIM (Oncology), ACVRVIN Consultant, Vet Oncol Serv, Edmonds, WA

Mark Rishniw, BVSc, MS, ACVIM (SAIM), ACVIM (Cardiology)

VIN Consultant, Clin Res Coord, Ithaca, NY

Kurt R. Verkest, BVSc, BVBiol, MACVSc (Small Animal)VIN Associate Editor, Univ Queensland, Australia