Calcifying Fibrous Pseudotumor

Definition

• 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

Immunohistology

Differential diagnosis

• Desmoplastic fibroblastoma / collagenous fibroma
• Calcifying aponeurotic fibroma
• Fibroma of tendon sheath
• Desmoid
• Solitary fibrous tumor
• Gastrointestinal stromal tumor

Clinical

• 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

Bibliography

• 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.