You are in: eMedicine Specialties > Dermatology > BENIGN NEOPLASMS Atypical FibroxanthomaArticle Last Updated: Feb 16, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: Forrest C Brown, MD, Clinical Professor of Dermatology, University of Texas Southwestern Medical School; Section Chief, Department of Dermatology, Medical City Dallas Hospital Editors: Carrie L Kovarik, MD, Assistant Professor, Department of Dermatology and Dermatopathology, University of Pennsylvania School of Medicine; Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University School of Medicine; Consulting Staff, Mountain View Dermatology, PA; Rosalie Elenitsas, MD, Associate Professor of Dermatology, University of Pennsylvania School of Medicine; Director, Penn Cutaneous Pathology Services, Department of Dermatology, University of Pennsylvania Health System; Joel M Gelfand, MD, MSCE, Medical Director, Clinical Studies Unit, Assistant Professor, Department of Dermatology, Associate Scholar, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania; William D James, MD, Paul R Gross Professor of Dermatology, University of Pennsylvania School of Medicine; Vice-Chair, Program Director, Department of Dermatology, University of Pennsylvania Health System Author and Editor Disclosure Synonyms and related keywords: AFX, sun exposure, photodamage, skin cancer, malignant fibrous histiocytoma, MFH, squamous cell carcinoma, squamous cell cancer, SCC, melanoma, nodular melanoma, sun damage, radiation exposure, radiation damage INTRODUCTIONSection 2 of 10
  BackgroundAtypical fibroxanthoma (AFX) is a tumor 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 excision. Clinicopathologic correlation is essential. Factors important to consider are lesion location, patient age, histopathologic appearance, and the observation that the tumor arises from the dermis, not the fat. Many AFX tumors 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. SexMale-to-female ratio is equal. AgeIn one study, age ranged from 13-95 years with a mean age of 69 years. CLINICALSection 3 of 10
History
Physical
CausesSun exposure and/or therapeutic radiation that have caused significant skin damage are associated with the development of AFX. The tumor primarily occurs on the head or neck of older individuals. DIFFERENTIALSSection 4 of 10
Dermatofibrosarcoma Protuberans Malignant Melanoma Squamous Cell Carcinoma
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Antibody | AFX | MFH | SCC | DFSP | Spindle MM* | Leiomyosarcoma |
|---|---|---|---|---|---|---|
| Vimentin | R | R | N | R | R | R |
| Cytokeratin | N | N | R | N | N | N |
| S-100 | N | N | N | N | R | N |
| Desmin or smooth muscle actin | N | N | N | N | N | R |
*Spindle cell malignant melanoma
New published data indicate that LN-2 antibody (CD74) and p53 immunoreactivity may help differentiate between malignant lesions in the fibrohistiocytic series, but further confirmation is needed. SCC, spindle cell MM, and leiomyosarcoma usually are differentiated using immunocytochemistry. No reliable consistent immunocytochemistry method is specific for AFX, and the diagnosis is based on typical histologic findings and the absence of immunomarker positivity for melanocytes, keratin, and smooth muscle actin.
DNA content quantification
Diploid or euploid cells have pairs or multiple pairs of chromosomes and usually are considered benign. Aneuploid cells have single or multiple single sets of chromosomes and are more common in malignant neoplasms.
Attempts to evaluate chromatin content in AFX have resulted in much confusion because of the methods of evaluation. The average picture produced with flow cytometry suggests that AFX is diploid. Using individual cell analysis, aneuploidy was found in giant cells, while diploidy has been found in smaller spindle-shaped cells. This picture is similar to MFH and does not allow nuclear cytometry to differentiate between MFH and AFX.
Histologic variants
Nonpleomorphic AFX (spindle cell AFX) was reported by Wilson-Jones et al in a series of cases of sun-damaged skin of the head and neck in older individuals. The immunocytochemistry findings and the tumors' benign clinical course supported the diagnosis of AFX. Pathologically, lesions were monomorphic, spindle-celled, fascicular variants without pleomorphic cells. All lesions were vimentin positive with approximately 50% showing focal actin activity. Desmin, keratin, and S-100 protein were negative in all cases.
In the past, many lesions were diagnosed clinically as granuloma pyogenicum and removed by shave and curettage, without recurrence, which has prompted physicians to treat AFX conservatively. Local recurrence and spread to lymph nodes may occur. This suggests that complete tumor removal is required. Simple excision with a margin of normal skin or Mohs micrographic surgery may be appropriate.
Evidence is accumulating rapidly that demonstrates that Mohs micrographic surgery, with its high reliability of complete tumor removal and tissue-conserving property, may be the treatment of choice for AFX on the head and neck.
Deterrence/Prevention:
| Media file 1: Red, beefy, sessile nodule typical of clinical presentation of atypical fibroxanthoma. Note the markedly sun-damaged skin with solar telangiectasias. Courtesy of Capt James Steger, MC, USN, US Naval Hospital, San Diego. | |
 | View Full Size Image | Media type: Photo |
| Media file 2: Microscopic view of atypical fibroxanthoma. Note the large abnormal-appearing cells in a field of spindle cells. Courtesy of Capt James Steger, MC, USN, US Naval Hospital, San Diego. | |
 | View Full Size Image | Media type: Photo |
Atypical Fibroxanthoma excerpt
Article Last Updated: Feb 16, 2007
