Stanford School of Medicine
Surgical Pathology Criteria
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Calcifying Fibrous Pseudotumor


  • Paucicellular collagenous lesion with scattered chronic inflammation and focal calcifications

Alternate / Historical Names

  • Calcifying fibrous tumor
  • Childhood fibrous tumor with psammoma bodies

Diagnostic Criteria

  • Paucicelluar
    • Bland spindle cells
      • Scant cytoplasm
      • Mitotic figures very rare
    • Scattered lymphocytes and plasma cells
      • Plasma cells usually predominate
      • May include germinal centers
      • May include eosinophils, neutrophils and mast cells
  • Abundant dense hyalinized collagenous stroma
    • Haphazard or whorled
  • Focal small calcifications
    • Range from psammomatous to irregular, dystrophic
    • Rarely ossifying
  • Varies from circumscribed to infiltrative
    • Not encapsulated
    • May be multilobulated
    • May entrap nerves, vessels and fat
  • Calcifying fibrous pseudotumor has been proposed to represent a sclerosing stage of inflammatory myofibroblastic tumor
  • Richard L Kempson MD
    Robert V Rouse MD
    Department of Pathology
    Stanford University School of Medicine
    Stanford CA 94305-5342

    Original posting: March 15, 2008


Supplemental studies


Factor XIIIa positive
CD34 variable
ALK negative to rare focal staining
Smooth muscle actin negative to rare focal staining
Muscle specific actin negative
Desmin rare focal staining
S100 negative


Differential diagnosis

Desmoplastic Fibroblastoma Calcifying Fibrous Pseudotumor
No calcification Calcification present
Large stellate cells Small spindled cells
Inflammation uncommon Chronic inflammation present


Calcifying Aponeurotic Fibroma Calcifying Fibrous Pseudotumor
Cellular lesion Paucicellular
Frequent chondroid stroma No chondroid stroma
Restricted to hands and feet Widely distributed
Broader areas of calcification Focal small calcifications


Fibroma of Tendon Sheath Calcifying Fibrous Pseudotumor
No calcification Calcification present
Inflammation uncommon Chronic inflammation present
Primarily located on digits Widely distributed
Slit-like vessels frequent Lacks slit-like vessels


Fibromatosis, Abdominal Desmoid and Extra-abdominal Desmoid Calcifying Fibrous Pseudotumor
Nearly always has cellular areas Uniformly paucicellular
Infiltrative pattern prominent Microscopically infiltrative at most
No calcification Calcification present
Inflammation uncommon Chronic inflammation present


Solitary Fibrous Tumor Calcifying Fibrous Pseudotumor
Frequently has cellular areas Uniformly paucicellular
Frequently has stag horn vessels Lacks prominent vascularity
No calcification Calcification present
Inflammation uncommon Chronic inflammation present


Calcifying Fibrous Pseudotumor GIST (spindled, bland)
Calcification frequently psammomatous Calcification dystrophic, not psammomatous
Patchy chronic inflammation Inflammation not typical
May form multinodular mass Not typically multinodular
Prominent hyalinized stroma Stroma occasionally sclerotic but not usually hyalinized


  • Most lesions under age 20
    • Range 1 month to 65 years
  • Location in subcutaneous tissue to deep soft tissue to viscera
  • No systemic symptoms
  • Size 0.6 to 25 cm
  • May recur
    • Not destructive
    • Never metastasizes


  • 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, 5th edition, 2008
  • Hill KA, Gonzalez-Crussi F, Chou PM.  Calcifying fibrous pseudotumor versus inflammatory myofibroblastic tumor: a histological and immunohistochemical comparison.  Mod Pathol 2001 Aug;14(8):784-90
  • Sigel JE, Smith TA, Reith JD, Goldblum JR.  Immunohistochemical analysis of anaplastic lymphoma kinase expression in deep soft tissue calcifying fibrous pseudotumor: evidence of a late sclerosing stage of inflammatory myofibroblastic tumor?  Ann Diagn Pathol 2001 Feb;5(1):10-4
  • Van Dorpe J, Ectors N, Geboes K, D'Hoore A, Sciot R.  Is calcifying fibrous pseudotumor a late sclerosing stage of inflammatory myofibroblastic tumor?  Am J Surg Pathol 1999 Mar;23(3):329-35
  • Ben-Izhak O, Itin L, Feuchtwanger Z, Lifschitz-Mercer B, Czernobilsky B.  Calcifying fibrous pseudotumor of mesentery presenting with acute peritonitis: case report with immunohistochemical study and review of literature.  Int J Surg Pathol 2001 Jul;9(3):249-53
  • Fetsch JF, Montgomery EA, Meis JM.  Calcifying fibrous pseudotumor.  Am J Surg Pathol 1993 May;17(5):502-8
  • Weynand B, Draguet AP, Bernard P, Marbaix E, Galant C.  Calcifying fibrous pseudotumour: first case report in the peritoneum with immunostaining for CD34.  Histopathology 1999 Jan;34(1):86-7
  • Nascimento AF, Ruiz R, Hornick JL, Fletcher CD. Calcifying fibrous 'pseudotumor': clinicopathologic study of 15 cases and analysis of its relationship to inflammatory myofibroblastic tumor. Int J Surg Pathol. 2002 Jul;10(3):189-96.
  • Zámecnik M, Michal M, Boudova L, Sulc M. CD34 expression in calcifying fibrous pseudotumours. Histopathology. 2000 Feb;36(2):183-4.
  • Kocova L, Michal M, Sulc M, Zamecnik M. Calcifying fibrous pseudotumour of visceral peritoneum. Histopathology. 1997 Aug;31(2):182-4.
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