Stanford School of Medicine

Surgical Pathology Criteria

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Pleomorphic Hyalinizing Angiectatic Tumor


  • Mitotically inactive tumor composed of large bizarre cells with prominent ectatic vessels

Alternate / historical names

Diagnostic criteria

  • Large spindled and epithelioid cells
    • Bizarre hyperchromatic nuclei
    • Frequent intranuclear inclusions
    • Abundant eosinophilic cytoplasm
    • Frequently contain hemosiderin
    • May contain pale cytoplasmic globules
  • Prominent large thin walled vessels
    • Frequently clustered
    • Fibrin in and around vessel walls
  • Stroma frequently hyalinized
  • Microscopically infiltrative borders
    • Predominantly subcutaneous, may involve dermis
    • Dermal lesions may surround skin adnexae
  • Mitotic figures very rare
  • Early lesion pattern
    • Short fascicles of bland spindled cells
      • Hemosiderin in cells
      • Infiltrates fat
      • Aggregates around groups of small blood vessels
    • Rare pleomorphic cells present
    • Small blood vessels focally ectatic with fibrin
    • Frequent myxoid matrix
    • Early features may be seen adjacent to classic pattern
    • Proposed to be equivalent to hemosiderotic fibrohistiocytic lipomatous lesion

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

Original posting:: September 15, 2007

Supplemental studies


  • Large pleomorphic cells
    • Vimentin positive
    • CD34 80% positive
  • Small spindled cells
    • Factor XIIIa positive
  • Negative: S100, keratin, EMA, smooth muscle actin, desmin, CD31

Genetic analysis

  • Diploid in 2 cases tested

Differential Diagnosis

Ancient Schwannoma Pleomorphic Hyalinizing Angiectatic Tumor
S100 positive S100 negative
CD34 negative on large cells CD34 80% positive on large cells
Usually encapsulated Microscopically infiltrative border
Vessels usually lack fibrin Fibrin frequent in and around vessels
Both schwannomas and PHAT may show pleomorphic cells with hyalinization and clusters of dilated vessels in a mitotically inactive tumor


MFH Pleomorphic Hyalinizing Angiectatic Tumor
Mitotic figures present, frequently atypical Mitotic figures rare
CD34 negative CD34 80% positive on large cells
Usually deep soft tissue Usually subcutaneous
Overall high cellularity Lacks high cellularity overall
Both MFH and PHAT may have increased Factor 13a positive cells


Pleomorphic Lipoma Pleomorphic Hyalinizing Angiectatic Tumor
No intracytoplasmic hemosiderin Intracytoplasmic hemosiderin
No aggregates of large vessels Aggregates of vessels with hyalinized walls and fibrin
Ropy collagen No ropy collagen
Restricted to back of neck, upper back and shoulders Various locations
Both are CD34 positive


Hemosiderotic Fibrohistiocytic Lipomatous Lesion has been proposed by Folpe and Weiss to represent early phase PHAT


  • Age 10-83 years
  • Size 0.3-20 cm
  • Most lesions subcutaneous
  • Most lesions on lower extremity
  • Recurrences in 6/18 cases with followup
    • One case recurred as high grade myxoid sarcoma
  • No metastases reported

Grading / Staging / Report

Grading and staging not applicable

The surgical pathology report should contain or address the following:

  • Location
  • Type of resection or biopsy
  • Histologic diagnosis
  • Managerial category Ib (Recurrences do occur but are not destructive; never metastasizes)
  • Size
  • Depth (dermis, subcutis, below fascia, body cavity)
  • Margins
    • Involved
    • Not involved
  • Results of supplementary studies if performed
  • Relationship to other specimens from the same patient


CD34 positive neoplasms (frequent and strong)


  • 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
  • Folpe AL, Weiss SW. Pleomorphic hyalinizing angiectatic tumor: Analysis of 41 cases supporting evolution from a distinctive precursor lesion. Am J Surg Pathol 2004 Nov; 28(11):1417-25 Biggest series, proposes a precursor pattern
  • Groisman GM, Bejar J, Amar M, Ben-Izhak O. Pleomorphic hyalinizing angiectatic tumor of soft parts: immunohistochemical study including the expression of vascular endothelial growth factor. Arch Pathol Lab Med 2000 Mar;124(3):423-6
  • Marshall-Taylor C, Fanburg-Smith JC. Hemosiderotic fibrohistiocytic lipomatous lesion: ten cases of a previously undescribed fatty lesion of the foot/ankle. Mod Pahtol. 2000;13:1192-9
  • Silverman JS, Dana MM. Pleomorphic hyalinizing angiectatic tumor of soft parts: immunohistochemical case study shows cellular composition by CD34+ fibroblasts and factor XIIIa+ dendrophages. J Cutan Pathol 1997 Jul;24(6):377-83
  • Smith ME, Fisher C, Weiss SW. Pleomorphic hyalinizing angiectatic tumor of soft parts. A low-grade neoplasm resembling neurilemoma. Am J Surg Pathol 1996 Jan;20(1):21-9. Original report, 14 cases.
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