Practical Oncology
Soft Tissue Sarcomas
Wendy Blount, DVM
Soft Tissue Sarcomas
• Locally invasive, but slow to metastasize
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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 excise
FNA 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 TX
Shawn Penn – Lufkin TX
Cytology
• Wispy cytoplasm with streaming tails
• Occasional binucleate cell
• Round to oval nuclei, inconspicuous nucleoli
Cytology
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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
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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 Lipoma
Well differentiated liposarcoma
Cytology
• Well differentiated fusiform & stellate cells
Cytology
• Well differentiated fusiform & stellate cells
• Low cellularity with granular background
Cytology
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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 Histiocytoma
Pleomorphic Undifferentiated Sarcoma
Surgery
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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 reexcised
• 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 postamputation 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)
FISS Update
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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
Acknowledgements
Philip 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), ACVR
VIN 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