Skin - Nonmelanocytic tumors
Other tumors of skin
Atypical fibroxanthoma (AFX)

Author: Christopher Hale, M.D., Vijay Shankar, M.D. (see Authors page)

Revised: 14 September 2016, last major update August 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Atypical fibroxanthoma

Cite this page: Atypical fibroxanthoma (AFX). website. Accessed October 28th, 2016.
Definition / General
  • Dermal variant of MFH-pleomorphic with low-grade behavior
  • Also called intermediate fibrous histiocytoma
  • Part of WHO classification for skin tumors, not soft tissue tumors
Clinical Features
  • Rapidly growing small dome-shaped or polypoid nodule on sun-damaged areas of head and neck of elderly (eMedicine - Atypical fibroxanthoma)
  • May present as bleeding ulcer < 2 cm
  • Rarely presents as large mass in limb or trunk of younger individuals, or post radiation therapy
  • May clinically resemble carcinoma
  • Must exclude tumors with AFX-like patterns, other lines of differentiation, significant involvement of subcutis, necrosis, vascular invasion or infiltrative margins (Stanford Medicine)
  • Poor prognostic indicators: history of immunosuppression, recurrence
Case Reports
Clinical Images

Images hosted on other servers:

Irregular polypoid tumors

21 year old woman with nasal nodule

Solitary dome shaped nodule

Gross Description
  • Polypoid, ulcerated, usually small
Micro Description
  • Well circumscribed, appears symmetric at scanning magnification
  • Bizarre multinucleated tumor cells in hypercellular, spindly stroma with frequent mitotic figures, many atypical
  • Also smaller fibroblastic, myofibroblastic and histiocyte-like cells with pleomorphism and angulated nuclei
  • Histologically identical to MFH-pleomorphic but centered in dermis
  • Background stroma appears inflammatory or reactive
  • Pushes aside surrounding pilosebaceous units and eccrine glands
  • Typically does not involve epidermis or subcutaneous tissue
  • Lacks classic features of fibrous histiocytoma (entrapped hyalinized collagen bundles and epidermal hyperplasia)
  • No grenz zone, no necrosis, no vascular invasion, no infiltrative margins
  • Variants: angiomatoid, chondroid, clear cell (J Cutan Pathol 2006;33:343), granular cell (Am J Dermatopathol 2007;29:84), keloidal (J Cutan Pathol 2009;36:535), myxoid (J Cutan Pathol 2009;36:1177), osteoclastic, osteoid, pigmented (Actas Dermosifiliogr 2009;100:321)
Micro Images

Images hosted on PathOut servers:

Marked cellularity and pleomorphism

Characteristic bizarre cells

Spindle variant has less pleomorphism

Tumor is limited to dermis
but otherwise resembles MFH
-pleomorphic with marked cellularity,
prominent pleomorphism, mitotic
figures and clumped chromatin

CD68 (left), CD10 (middle), and AE1-AE3 (right), contributed by Dr. Angel Fernandez-Florez

Contributed by Dr. Angel Fernandez-Florez

Images hosted on other servers:

Ulcerated tumor

Spindle and epithelioid cells with atypia

Nodular spindle cell tumor

81 year old woman with lower leg lesion

Factor XIIIa

Fig 1: eyebrow primary
Fig 2 - 4: facial metastasis (fig 4 is CD68)

Negative Stains
Electron Microscopy Description
  • Myofibroblasts, fibroblasts and primitive mesenchymal cells
Molecular / Cytogenetics Description
  • Diploid
Differential Diagnosis