External ear tumors - benign / nonneoplastic
Atypical fibroxanthoma

Topic Completed: 1 October 2013

Revised: 26 August 2019

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PubMed Search: Atypical fibroxanthoma [title] ear

Nat Pernick, M.D.
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Cite this page: Pernick N. Atypical fibroxanthoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/earafx.html. Accessed December 10th, 2019.
Definition / general
  • Also called superficial malignant fibrous histiocytoma
  • Usually sun damaged skin of elderly (75% in head and neck) or superficial soft tissue of extremities in young
Case reports
  • Excellent prognosis with complete excision
  • Local recurrence if incomplete excision
  • Probably cannot metastasize
  • May recur as large mass in deep soft tissue which should be treated as malignant fibrous histiocytoma (not superficial)
Gross description
  • Asymptomatic firm nodule, 1 - 2 cm, often with ulceration
Microscopic (histologic) description
  • Nonencapsulated but circumscribed spindle cell proliferation of dermis
  • Cells are spindled or pleomorphic with bizarre multinucleated forms or hyperchromasia
  • Cells may have foamy cytoplasm, increased mitotic figures including atypical forms
  • May have vascular invasion
  • No junctional activity, no necrosis
Positive stains
Negative stains
Differential diagnosis
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