Stanford School of Medicine

Surgical Pathology Criteria

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  • Circumscribed edematous lesion of the external genitalia and perineal soft tissue

Diagnostic Criteria

  • Restricted to external genitalia and perineal soft tissue
    • Rare in males
  • Most under 5 cm
  • Circumscribed with thin pseudocapsule
  • Edematous background with prominent vascularity
    • Thin walled dilated capillaries and venules
    • Scattered bundles of collagen
    • Occasionally sclerotic
    • No necrosis
  • Alternating hypercellular and hypocellular areas
    • Cells frequently aggregated around vessels
      • Nests and occasional solid compact foci
      • Also scattered individual cells
      • Hypocellular areas can resemble aggressive angiomyxoma except the vessels are not as thick walled
    • Spindle to round cells
      • May be epithelioid
      • May have plasmacytoid appearance
      • Eosinophilic cytoplasm, occasionally hyaline
      • Bland to minimally atypical oval nuclei
        • Inconspicuous nucleoli
        • Mitotic figures rare, no atypical mitotic figures
      • Binucleate and multinucleate cells common
  • Frequently fat in lesion
    • Not clear if this is entrapped or lesional fat
    • May occasionally be prominent ("lipomatous variant")
    • Two reported scrotal lesions were predominantly adipose tissue
  • Occasional findings
    • Prominent spindle cell population
    • Stellate cells
    • Degenerative nuclear hyperchromasia
    • Mast cells may be numerous

Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting:: May 27, 2007

Supplemental studies


Desmin Most cases positive
Smooth muscle actin Occasional focal
Muscle specific actin Occasional, focal
CD34 Variable, about 50%
Factor XIIIa Small spindle cells, some cases
Vimentin Positive
Estrogen receptor Positive most cases
Progesterone receptor Positive most cases
S100 Negative
Keratin Negative
CD57 Negative


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


    • Age 23-88 years
    • Predominantly subcutaneous
    • 0.5-14 cm
      • Rarely over 10 cm
    • Involves external genitalia and perineal soft tissssue
    • Occasionally involves vagina
    • Nearly all in females
      • Rarely involves scrotum or inguinal region in males
    • Does not recur

    Grading / Staging / Report

    Grading and staging are not applicable

    The surgical pathology report should contain or address the following:

    • Location
    • Type of resection or biopsy
    • Histologic diagnosis
    • Managerial category Ia (Local excision is almost always curative; metastasis never occurs)
    • Size
    • Depth (dermis, subcutis, below fascia, body cavity)
    • Results of supplementary studies if performed
    • Relationship to other specimens from the same patient



    Vulvovaginal stromal and spindled tumors


    • Kempson RL, Fletcher CDM, Evans HL, Henrickson MR, Sibley RS. Tumors of the Soft Tissues, Atlas of Tumor Pathology, AFIP Third Series, Fascicle 30, 2001
    • Fletcher CDM, Unni KK, Mertens F. Pathology and Genetics of Tumours of Soft Tissue and Bone, World Health Organization Classification of Tumours 2002
    • Weiss SW, Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors, 4th edition, 2001
    • Bigotti G, Coli A, Gasbarri A, Castagnola D, Madonna V, Bartolazzi A. Angiomyofibroblastoma and aggressive angiomyxoma: two benign mesenchymal neoplasms of the female genital tract. An immunohistochemical study. Pathol Res Pract 1999;195(1):39-44.
    • Fletcher CD, Tsang WY, Fisher C, Lee KC, Chan JK. Angiomyofibroblastoma of the vulva. A benign neoplasm distinct from aggressive angiomyxoma. Am J Surg Pathol 1992 Apr;16(4):373-82.
    • Fukunaga M, Nomura K, Matsumoto K, Doi K, Endo Y, Ushigome S. Vulval angiomyofibroblastoma. Clinicopathologic analysis of six cases. Am J Clin Pathol 1997 Jan;107(1):45-51.
    • Granter SR, Nucci MR, Fletcher CD. Aggressive angiomyxoma: reappraisal of its relationship to angiomyofibroblastoma in a series of 16 cases. Histopathology 1997 Jan;30(1):3-10.
    • Hisaoka M, Kouho H, Aoki T, Daimaru Y, Hashimoto H. Angiomyofibroblastoma of the vulva: a clinicopathologic study of seven cases. Pathol Int 1995 Jul;45(7):487-92.
    • Katenkamp D, Kosmehl H, Mentzel T, Reinke J. [Angiomyofibroblastoma of the vulvar and paravaginal region--a new entity] Pathologe 1993 May;14(3):131-7 [Article in German]
    • Laskin WB, Fetsch JF, Mostofi FK. Angiomyofibroblastomalike tumor of the male genital tract: analysis of 11 cases with comparison to female angiomyofibroblastoma and spindle cell lipoma. Am J Surg Pathol 1998 Jan;22(1):6-16.
    • Laskin WB, Fetsch JF, Tavassoli FA. Angiomyofibroblastoma of the female genital tract: analysis of 17 cases including a lipomatous variant. Hum Pathol 1997 Sep;28(9):1046-55.
    • Nielsen GP, Rosenberg AE, Young RH, Dickersin GR, Clement PB, Scully RE. Angiomyofibroblastoma of the vulva and vagina. Mod Pathol 1996 Mar;9(3):284-91.
    • Nielsen GP, Young RH, Dickersin GR, Rosenberg AE. Angiomyofibroblastoma of the vulva with sarcomatous transformation ("angiomyofibrosarcoma"). Am J Surg Pathol 1997 Sep;21(9):1104-8.
    • Nucci MR, Granter SR, Fletcher CD. Cellular angiofibroma: a benign neoplasm distinct from angiomyofibroblastoma and spindle cell lipoma. Am J Surg Pathol 1997 Jun;21(6):636-44.
    • Ockner DM, Sayadi H, Swanson PE, Ritter JH, Wick MR. Genital angiomyofibroblastoma. Comparison with aggressive angiomyxoma and other myxoid neoplasms of skin and soft tissue. Am J Clin Pathol 1997 Jan;107(1):36-44.
    • Silverman JS, Albukerk J, Tamsen A. Comparison of angiomyofibroblastoma and aggressive angiomyxoma in both sexes: four cases composed of bimodal CD34 and factor XIIIa positive dendritic cell subsets. Pathol Res Pract 1997;193(10):673-82.
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