Aggressive Angiomyxoma Differential Diagnosis
The first four entities are predominantly perineal in location and may be confused with aggressive angiomyxoma
Angiomyofibroblastoma Aggressive Angiomyxoma
Most <5 cm
Nearly always >5 cm
Well circumscribed
Not circumscribed
Alternating hypercellular and hypocellular areas
Hypocellular
Clusters of rounded, epithelioid, frequently plasmacytoid cells
Sparse spindled or stellate cells
Numerous small vessels
Large thick walled vessels
Actin frequently positive
Actin infrequently positive
Cases with features of both occur raising the possibility that they form a spectrum.
Size may be a critical distinguishing feature.
Immunohistochemistry reports of actin staining are variable and thus it may not be reliable for separation; both are desmin positive.
Aggressive Angiomyxoma Cellular Angiofibroma
Usually large, deep lesion
Subcutaneous, mean size 6 cm
Hypocellular
Moderately cellular
Infiltrative margin
Circumscribed
Usually desmin positive
Desmin 10% positive
May infiltrate fat
May have fat integral to lesion
Both have prominent medium sized vessels, both may be CD34+.
Both are frequently positive for desmin, CD34, ER, PR
Fibroepithelial stromal polyp
Aggressive Angiomyxoma
Exophytic
Sessile, deep lesion
Often extends to overlying epithelium
Practically never extends to overlying epithelium
Vaginal or cervical
Usually in soft tissue
Usually <5 cm
Nearly always >5 cm
May have scattered atypical stromal cells
No atypical cells
Both contain desmin positive cells
Superficial Angiomyxoma Aggressive Angiomyxoma
Usually <5 cm
Nearly always >5 cm
Superficial
Deep seated
Long thin walled vessels
Medium to large thick walled vessels
Desmin negative
Desmin positive
Stromal neutrophils
No stromal neutrophils
Aggressive angiomyxoma is virtually restricted to perineal, genital, inguinal regions, while the myxoid entities considered below may occur in a wide variety of sites.
