Surgical Pathology Criteria–

Angiomyofibroblastoma

Differential Diagnosis

The first four entities are predominantly perineal in location and may be confused with angiomyofibroblastoma

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.

    • Fibroepithelial stromal polyp Angiomyofibroblastoma
    Exophytic Sessile
    Submucosal Subcutaneous
    Poorly circumscribed Well circumscribed
    Frequent bizarre stromal cells Bland cells
    Both usually contain desmin positive stromal cells

    Angiomyofibroblastoma Cellular Angiofibroma
    Alternating hypercellular and hypocellular areas Uniformly moderately cellular
    Numerous small vessels Hyalinized round vessels
    Clusters of rounded, epithelioid cells, often around vessels Bland spindle cells
    Desmin positive most cases Desmin about 10% of cases
    Numerous small vessels Large thick walled vessels
    Actin frequently positive Actin infrequently positive
    Both may have fat in lesion, both may be CD34+.

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

    Superficial Angiomyxoma Angiomyofibroblastoma
    Long thin walled vessels Numerous capillaries and venules
    Desmin negative Desmin positive
    Stromal neutrophils No stromal neutrophils

    Perivascular clustering of cells in angiomyofibroblastoma may suggest glomus tumor
    Glomus tumor Angiomyofibroblastoma
    Very regular round cells Spindled and round cells
    Uniform cellularity Alternating cellularity
    Actin positive Actin variable

    Clusters of epithelioid cells in angiomyofibroblastoma may suggest epithelioid leiomyoma
    Epithelioid leiomyoma Angiomyofibroblastoma
    Generally more cellular Alternating cellularity
    Generally actin positive Frequently actin negative
    Both are usually desmin positive

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