Epithelioid Sarcoma

Differential Diagnosis

Central necrosis of epithelioid sarcoma may simulate granulomatous disease, infectious or autoimmune

Palisaded Necrotic Granuloma	Epithelioid Sarcoma
Keratin negative	Keratin positive
CD34 negative	CD34 50% positive
Indistinct cytoplasm	Sharply defined eosinophilic cytoplasm
Rheumatoid nodules uncommon on hand and wrist	Common on hand and wrist

Always think of epithelioid sarcoma when an extremity lesions looks granulomatous

Keratin positivity is typically seen in both

Squamous Carcinoma	Epithelioid Sarcoma
CD34 negative	CD34 50% positive
Uncommon in young people	Most patients under 40 years
May have in situ lesion or keratinization	No in situ lesion or keratinization
May have history of epithelial primary	No primary epithelial lesion
CK5/6 commonly extensive	CK5/6 rare, focal
CA125 negative in cutaneous SCC, frequently positive in SCC of other sites	CA125 90% positive

CD34 reactivity is very rare in carcinoma of any type

Keratin positivity is typically seen in both

Sweat Gland Carcinoma	Epithelioid Sarcoma
CD34 negative	CD34 50% positive
May express GCDFP15, S100, actin	GCDFP15, S100, actin negative

CD34 reactivity is very rare in carcinoma of any type

Both may present as keratin positive spindle cell neoplasms

Epithelioid Sarcoma	Monophasic Synovial Sarcoma
Usually superficial	Usually deep
Necrosis frequently extensive	Necrosis usually focal
CD34 50% positive	CD34 negative
No ropy collagen	Ropy collagen frequent
Calcification infrequent	Calcification frequent
No hemangiopericytomatous vessels	Hemangiopericytomatous vessels frequent
No SYT-SSX gene fusion	SYT-SST gene fusion present
TLE1 0% (0/2)	TLE1 97%
CA125 90% positive	CA125 negative

Abundant well defined cytoplasm in a dermal tumor may simulate melanoma

Melanoma	Epithelioid Sarcoma
S100, HMB45 positive	S100, HMB45 negative
Keratin very rare	Keratin positive
CD34 negative	CD34 50% positive
May have adjacent junctional component	No junctional component
CA125 negative	CA125 90% positive
INI1 positive	INI1 loss in 91%

Epithelioid Hemangioendothelioma	Epithelioid Sarcoma
CD31 usually positive	CD31 negative
Keratin negative	Keratin positive
Uncommon on distal extremities	Common distally
Frequently small nested pattern	Nodular or sheets
May be centered on a vessel	Not centered on a vessel

Epithelioid Sarcoma	Sclerosing Epithelioid Fibrosarcoma
EMA and keratin often strongly positive	EMA and keratin negative or focal and weak
Often granuloma-like	Cords of cells in hyalinized stroma
Eosinophilic cytoplasm	Clear cytoplasm

Epithelioid Sarcoma	Ischemic Fasciitis
Usually extremities of young patient	Usually shoulder or hip of elderly patient
Usually brightly eosinophilic cytoplasm	Cytoplasm usually basophilic or amphophilic
Keratin positive	Keratin negative

Both are frequently CD34 positive