Atypical Fibroxanthoma (AFX)

Atypical Fibroxanthoma (AFX)

AFX is a tumour that occurs primarily in older individuals after the skin of the head and neck has been damaged significantly by sun exposure and/or therapeutic radiation. Clinically, lesions usually are suggestive of malignancy because they arise rapidly (over just a few weeks or months) in skin in which other skin cancers have been found and treated. When this clinical impression is combined with highly anaplastic pathology, misdiagnosis can result in unnecessary and extensive surgery and radiation.

Histologically, lesions show a highly atypical and pleomorphic cellular appearance, but they typically respond to simple local excision. Clinicopathologic correlation is essential. Factors important to consider are lesion location, patient age, histopathologic appearance, and the observation that the tumour arises from the dermis, not the fat. Many AFX tumours may represent a superficial form of malignant fibrous histiocytoma (MFH) with a much better prognosis. Some cases may represent primary squamous cell carcinoma (SCC) that fails to express keratin.

Sex: Male-to-female ratio is equal.

Age:  In one study, age ranged from 13-95 years with a mean age of 69 years.

History : Typically, the patient presenting with AFX is an older individual (mean age 69 y) with sun-damaged or radiation-damaged skin of the head, neck, and scalp.

Physical:

  • Nodules are red, juicy, and dome shaped and they may be ulcerated. Lesions are usually located on skin that is red, thin, and telangiectatic, indicating previous significant sun or radiation damage. Some nodules are dark enough, due to deposits of haemosiderin, to be confused with a nodular melanoma.
  • Nodules primarily are located on the head and neck and in sun-exposed areas. In addition, lesions have been reported to occur on the trunk, extremities, and in sun-protected areas. The ratio of lesions that occur on the head and neck to lesions that occur in other areas is approximately 4:1.
  • Tumour size increases proportionately with duration of existence but rarely exceeds 3 cm in diameter.
  • Lesion growth typically is rapid, and patients usually seek medical advice within 6 months of onset.
  • In adult cases, skin underlying developing AFX lesions may be considered locally immunosuppressed. Recent reports showed an increased incidence of AFX in patients with AIDS and in patients who are immunosuppressed because of organ transplantation.
  • One case of localized cutaneous metastases has been reported after excision of the primary lesion. This seems to be extremely rare.

Causes

Sun exposure and/or therapeutic radiation that have caused significant skin damage are associated with the development of AFX. The tumour primarily occurs on the head or neck of older individuals.

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  1. #1 by Dr. Isabelle Jonsson on August 12, 2011 - 9:59 am

    Do we manage these like SCC’s or like a completely benign lesion?? If you performed a shave biopsy and the result is an AFX, do you proceed to excision or reassure the patient?

    • #2 by Dr Ian Katz on August 12, 2011 - 12:53 pm

      Wide local excision is the correct management, definitely after a shave as well
      Ian

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