Calcifying fibrous pseudotumor versus inflammatory myofibroblastic tumor: A histological and immunohistochemical comparison

Kalisha A. Hill, Frank Gonzalez-Crussi, Pauline M. Chou

Research output: Contribution to journalArticlepeer-review

126 Scopus citations


Calcifying fibrous pseudotumor (CFP), a recently described lesion, is characterized by a predominantly lymphoplasmacytic infiltrate with abundant hyalinized collagen and psammomatous or dystrophic calcifications. The cause and pathogenesis are unclear, but it has been postulated that CFP may represent a sclerosing end stage of inflammatory myofibroblastic tumor (IMT). We compared the histological and immunohistochemical profiles of seven cases diagnosed as CFP and seven as IMT. Histologically, the CFP demonstrated varying degrees of calcifications in addition to fibroblastic proliferation admixed with inflammatory cells composed of lymphocytes, eosinophils, and mast cells. The IMTs rarely contain calcifications and had a myofibroblastic proliferation varying from hyalinized acellular collagen to florid fibroblastic proliferations simulating sarcoma. The inflammatory component was composed primarily of plasma cells and lymphocytes, sometimes arranged as lymphoid aggregates with germinal centers. All CFP cases were diffusely positive for factor XIIIa and negative for smooth muscle actin, muscle-specific actin, and CD34. All IMTs demonstrated diffuse positivity for actin, variable positivity for CD34, and focal positivity for Factor XIIIa. This study demonstrates certain distinct histologic, immunohistochemical, and electron microscopic features between IMTs and CFPs.

Original languageEnglish (US)
Pages (from-to)784-790
Number of pages7
JournalModern Pathology
Issue number8
StatePublished - 2001


  • Calcifying fibrous pseudotumor
  • Dendritic cell
  • Factor XIIIa
  • Inflammatory myofibroblastic tumor
  • Myofibroblast-CD34
  • Soft tissue tumor

ASJC Scopus subject areas

  • Pathology and Forensic Medicine


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