Factor XIIIa

Author: Nat Pernick, M.D. (see Authors page)

Revised: 25 January 2017, last major update August 2012

Copyright: (c) 2003-2017,, Inc.

PubMed Search: Factor XIIIa
Cite this page: Factor XIIIa. website. Accessed June 20th, 2018.
Definition / general
  • Fibrohistiocytic marker; note that peritumoral cells may also exhibit Factor XIIIa staining
  • Also active form of factor XIII, an enzyme of coagulation system that crosslinks fibrin (Wikipedia)
Uses by pathologists
  • Marker of fibrohistiocytic proliferations
  • Marker of dermal dencrocytes
  • Differentiate dermatofibrosarcoma protuberans (CD34+, D2-40-, Factor XIIIa-) from dermatofibroma (CD34-, Factor XIIIa+, D2-40+)
Microscopic (histologic) images

Images hosted on Pathout server:

Epithelioid fibrous histiocytoma

Images hosted on other servers:

Atypical fibroxanthoma

Positive staining - normal
  • Dermal dendrocytes
Positive staining - disease
  • Soft tissue: benign fibrous histiocytoma and variants, malignant fibrous histiocytoma
  • Also calcifying fibrous tumor (Mod Pathol 2001;14:784), verruciform xanthoma
  • Also atypical fibroxanthoma (focal), hemangiopericytoma (scattered), myofibroblastoma in lymph nodes (variable), pleomorphic hyalinizing angiectatic tumor (focal), storiform collagenoma (scattered)
  • Cervix: aggressive angiomyxoma
  • CNS: Erdheim-Chester disease
Negative staining