Superficial Myofibroblastoma

Differential Diagnosis

The first six entities are predominantly perineal in location and may be confused with superficial myofibroblastoma

Superficial Myofibroblastoma	Angiomyofibroblastoma
Inconspicuous vascularity	Prominent vascularity
Stellate and spindled cells	Perivascular epithelioid cells

Fibroepithelial Stromal Polyp	Superficial Myofibroblastoma
Wide age range	Most 40-70's
Superficial lesional cells, hypocellular core	Lesional cells throughout
No grenz zone	Usually grenz zone
May have bizzare stromal cells	No bizzare stromal cells
No architectural pattern	Frequent lace-like pattern

Cellular Fibroepithelial Stromal Polyp	Superficial Myofibroblastoma
Young, frequently pregnant	Most 40-70's
Cellularity predominanlty superficial	Cellularity varies throughout
No grenz zone	Usually grenz zone
Scattered bizarre or multinucleated cells	Uniform bland cells
Mitotic figures may be frequent	Mitotic figures <1/10 hpf

Superficial Myofibroblastoma	Cellular Angiofibroma
Desmin positive	Desmin 10% positive
Inconspicuous thin walled vessels	Prominent thick walled vessels
No fat	Frequently contains fat
ER and PR >90%	ER and PR 35-55%

Both are superficial and may be CD34 postive. Cellular angofibroma may occur in males.

Superficial Myofibroblastoma	Aggressive Angiomyxoma
Age 40-70's	Young patients
Small, superficial	Large, deep
Circumscribed	Frequently infiltrative
Inconspicuous vessels	Prominent thick walled hyalinized vessels

Both are frequently positive for desmin, CD34, ER, PR

Vaginal Spindle Cell Epithelioma	Superficial Myofibroblastoma
Squamous or glandular component	No epithelial component
Keratin postive	Keratin negative
Desmin negative	Desmin positive

Superficial myofibroblastoma is restricted to perineal and genital regions, while the entities considered below may occur in a wide variety of sites.

Superficial Angiomyxoma	Superficial Myofibroblastoma
Mean age 20 years for perineal lesions	Most 40-70's
Long thin walled vessels	Inconspicuous vessels
Desmin, ER, PR negative	Desmin, ER, PR positive
S100 variable	S100 negative
Stromal neutrophils	No stromal neutrophils
Frequently multinodular	Single nodule
Frequently involves subcutis	Superficial
Paucicellular	Cellular areas

Nerve Sheath Tumor	Superficial Myofibroblastoma
S100 positive	S100 negative
Desmin negative	Desmin positive

Both may be CD34 positive

Solitary Fibrous Tumor	Superficial Myofibroblastoma
Frequent stag horn vessels	Inconspicuous vessels
Desmin negative	Desmin positive
CD34 positive	CD34 variable