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E-JCRT CORRESPONDENCE
Year : 2015  |  Volume : 11  |  Issue : 4  |  Page : 1027

Atypical fibroxanthoma in a young female misdiagnosed clinically as a malignant melanoma- An unusual presentation


Department of Pathology, Hamdard Institute of Medical Sciences and Research, New Delhi, India

Date of Web Publication15-Feb-2016

Correspondence Address:
Sujata Jetley
Department of Pathology, Hamdard Institute of Medical Sciences and Research, New Delhi - 110 044
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0973-1482.150353

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 > Abstract 


Atypical fibroxanthoma (AFX) is an uncommon spindle cell tumor with intermediate or borderline malignant potential. Clinically, it may be misdiagnosed as a squamous cell carcinoma (SCC) or malignant melanoma. Solar irradiation has been implicated in its pathogenesis. The diagnosis of AFX rests on a combination of histopathological features and a negative immunohistochemical profile. AFX is a rare tumor usually found in sun exposed skin of head and neck region in elderly Caucasian men. Rarely, it has a second peak in young adults, where it is found in trunk and extremities. The present case is reported as AFX is quite unusual in a young female with a nodule in the leg which was clinically diagnosed as a malignant melanoma. Only a few cases of AFX have been reported in young women. This case highlights the fact that accurate diagnosis of atypical fibroxanthoma is very crucial so as to avoid overenthusiastic and overzealous treatment as required for a malignant tumor.

Keywords: Atypical fibroxanthoma, female, malignant melanoma, young


How to cite this article:
Pujani M, Hassan MJ, Jetley S. Atypical fibroxanthoma in a young female misdiagnosed clinically as a malignant melanoma- An unusual presentation. J Can Res Ther 2015;11:1027

How to cite this URL:
Pujani M, Hassan MJ, Jetley S. Atypical fibroxanthoma in a young female misdiagnosed clinically as a malignant melanoma- An unusual presentation. J Can Res Ther [serial online] 2015 [cited 2019 Oct 14];11:1027. Available from: http://www.cancerjournal.net/text.asp?2015/11/4/1027/150353




 > Introduction Top


Atypical fibroxanthoma (AFX) is a rare skin tumor that characteristically follows a benign clinical course despite its ominous and malignant appearing histological picture. It usually occurs on the sun exposed skin of head and neck region in elderly. Clinically, it may be misdiagnosed as a squamous cell carcinoma or malignant melanoma. Solar irradiation has been implicated in its pathogenesis. The diagnosis of AFX rests on a combination of histopathological features and a negative immunohistochemical profile (negative S-100 rules out malignant melanoma while a negative cytokeratin excludes squamous cell carcinoma).[1],[2]

We hereby report an unusual case of atypical fibroxanthoma of leg in a 24-year-old female which was clinically suspected to be a melanoma. Correct diagnosis is important to prevent underreporting and sometimes exaggerated treatment if interpreted as a malignancy.


 > Case Report Top


A 24-year-old female presented with a gradually enlarging nodular lesion on left leg for the last 2 months. The lesion was firm, non tender, 2 × 1.5 cm nodule with an increased pigmentation of the overlying skin. The nodule was fixed to the skin but not to the underlying structures. A clinical diagnosis of malignant melanoma was suspected. A surgical excision was performed and tissue sent for histopathology. Grossly, a skin covered nodule was received measuring 2 × 1.5 × 1 cm with brown pigmentation of overlying skin. On cutting, nodule was solid with yellowish orange appearance reaching the subcutaneous tissue. The surgical resection margin was free of tumor. Microscopically, a tumor was observed in the dermis extending into the subcutaneous tissue composed of bizarre cells arranged in a haphazard fashion [Figure 1]. Tumor cells were spindle to epithelioid with presence of many scattered multinucleated giant cells [Figure 2]. Nuclei were large, pleomorphic with many mitotic figures. No areas of necrosis were observed. Immunohistochemically, the tumor cells were positive for α-1 anti trypsin and CD 68 while they were negative for cytokeratin and HMB-45. Thus, a final diagnosis of atypical fibroxanthoma was rendered.
Figure 1: Photomicrograph showing a tumor located in the dermis without involvement of epidermis (H and E, ×100)

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Figure 2: Photomicrograph showing (a) bizarre spindle to epithelioid tumor cells arranged in a haphazard fashion; inset strong α-1 (b) Many scattered multinucleated giant cells also seen (H and E, ×400)

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 > Discussion Top


Atypical fibroxanthoma (AFX) is an uncommon spindle cell tumor with intermediate or borderline malignant potential. It was first reported by Helwig in 1963.[3] AFX was initially described as a benign process despite its atypical appearance (bizarre xanthoma cells, multinucleation). Metastatic potential of AFX was first described in 1986.[4]

AFX is a rare tumor usually found in sun exposed skin of head and neck region in elderly Caucasian men. Rarely, it has a second peak in young adults, where it is found in trunk and extremities. The present case is reported as AFX is quite unusual in a young female with a nodule in the leg which was clinically diagnosed as a malignant melanoma. Only a few cases of AFX have been reported in young women.[5],[6],[7]

AFX clinically presents as a rapidly growing, erythematous or flesh colored nodular lesion on sun damaged skin which may show ulceration. Most of the lesions are smaller than 2 cm in diameter. The list of clinical differential diagnosis of atypical fibroxanthoma is diverse including squamous cell carcinoma (SCC), basal cell carcinoma (BCC), keratoacanthoma, malignant fibrous histiocytoma (MFH), dermatofibrosarcoma protuberans (DFSP), malignant melanoma (MM), Kaposi sarcoma etc., the present case was also misdiagnosed clinically as a malignant melanoma.[1]

AFX has been suggested to be a reactive or reparative process developing in response to chronic skin injury induced by solar irradiation. Moreover, some reports of occurrence of AFX in patients with internal malignancy point towards a defective immune response of host.[1],[4]

Histopathologically, AFX is seen as an unencapsulated tumor located in dermis without any involvement of epidermis. The tumor cells are large, pleomorphic spindle to epithelioid type arranged in a haphazard manner. Bizarre xanthomatous cells as well as multinucleated giant cells are also present. Histological variants of AFX include clear cell, granular cell, osteoclastic giant cell and pigmented AFX.

The diagnosis of AFX is one of exclusion, based on immunohistochemistry. Several authors have studied various markers in the diagnosis of AFX.[2],[8] Malignant melanoma is ruled out by a negative S-100/HMB 45 staining while SCC and BCC are excluded by a negative staining for cytokeratin. AFX typically stains positive for α-1 anti trypsin, CD 68, CD 99.

The most important and close differential diagnosis of AFX is MFH from which it must be distinguished using the following features: Depth of involvement, necrosis and increased mitosis. In the present case also, the tumor was located in dermis without areas of necrosis which favored AFX. Malignant melanoma usually has a typical nesting pattern as well as positive immunostaining for S-100 or HMB 45 which helps in differentiating it from AFX. Involvement of the overlying epidermis and an epithelial architectural pattern favors a SCC, moreover, positive cytokeratin staining helps in reaching at an accurate diagnosis.[1]

The treatment of choice for AFX is complete local surgical excision till the subcutaneous tissue. Superficial radiotherapy can be used as an adjunctive therapy. Recurrence rate following excision is 7%, many of which occur within a year of surgery. Features indicating a poor prognosis include previous radiation, vascular invasion, deep invasion, recurrence and tumor necrosis.[9]

It is very essential to correctly establish the diagnosis of AFX so as to avoid overenthusiastic and overzealous treatment as required for a malignant tumor.

 
 > References Top

1.
Avolio AM, Lee S, Mann S. Sixteen photogenic wonders from down under: A case series of atypical fibroxanthoma from Australia. Hong Kong J Dermatol Venereol 2011;19:167-74.  Back to cited text no. 1
    
2.
Luzar B, Calonje E. Morphological and immunohistochemical characteristics of atypical fibroxanthoma with a special emphasis on potential diagnostic pitfalls: A review. J Cutan Pathol 2010;37:301-9.  Back to cited text no. 2
    
3.
Helwig EB. Atypical fibroxanthoma: Proceedings of 18th annual tumor seminar of San Antonio Society of Pathologists, 1961. Tex State J Med 1963;59:664-7.  Back to cited text no. 3
    
4.
Helwig EB, May D. Atypical fibroxanthoma of the skin with metastasis. Cancer 1986;57:368-76.  Back to cited text no. 4
[PUBMED]    
5.
Melendez MM, Xu X, McClain SA, Huang SD. Atypical fibroxanthoma in a young woman: An unusual case presentation. Can J Plast Surg 2007;15:169-72.  Back to cited text no. 5
    
6.
Jacobs DS, Edwards WD, Ye RC. Metastatic atypical fibroxanthoma of skin. Cancer 1975;35:457-63.  Back to cited text no. 6
[PUBMED]    
7.
Lee SM, Zhang W, Fernandez MP. Atypical fibroxanthoma arising in a young patient with Li-Fraumeni syndrome. J Cutan Pathol 2014;41:303-7.  Back to cited text no. 7
    
8.
Singh M, Mann R, Ilankovan V, Hussein K, D'arrigo C. Atypical Fibroxanthoma--A retrospective immunohistochemical study of 42 cases. J Oral Maxillofac Surg 2012;70:2713-8.  Back to cited text no. 8
    
9.
Erdem H, Turan H, Aliagaoglu C, Kadioglu N, Sezen GY, Iskender A. Atypical fibroxanthoma in a woman and literature review. J Cranio Max Dis 2012;1:126-30.  Back to cited text no. 9
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