Ann Clin Case Rep | Volume 6, Issue 1 | Case Series | Open Access

Aneurysmal Atypical Fibroxanthoma. A Clinical Mimicker of Nodular Malignant Melanoma: Report of Two Cases and Review of the Literature

Vallejo-Benítez A1*, Rodríguez-Zarco E2, García-Castro R3, Macías-García L2, Pérez-Pérez M1, Santos-Briz A3 and Ríos-Martín JJ1

1Hu Virgen Macarena, Spain 2University of Seville, Spain 3Complejo Asistencial Universitario de Salamanca, Spain

*Correspondance to: Vallejo-Benítez A 

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Background: Atypical Fibroxanthoma (AFX) is a dermal tumor of uncertain histogenesis and presents as irregularly pigmented, dome-shaped nodules or plaques on sun-exposed skin of elderly patients. Several histological variants of AFX have been described. The hemosiderotic and aneurysmal variants are not clearly defined in the literature. Objectives: Two cases of an uncommon histopathological variant of Atypical Fibroxanthoma (AFX) are described. Were view the literature and the histopathological features and differential diagnosis are discussed. Material and Methods: Histological features analyzed in both cases were: Cytology, ulceration, size, and growth pattern, depth of invasion and tumor borders, mitotic activity, necrosis, and vascular/ Perineural invasion. The antibodies used were CD68, CD10, p63, p40, S100, CD31, CD34, ERG, D2- 40, Fli-1, desmin, SMA, CK-AE1/AE3 and HMB45. Clinical features were reviewed for metastases, disease status, treatment, and any other pre-existing conditions. Results: We present two cases of FXA melanoma diagnosed, with 65 and 94 years old, respectively. Both developed on sun damaged skin. Ulceration was present in one case. Morphological patterns were spindle cells arranged around multiple aneurysmal pseudo cystic spaces with no endothelial lining. Hemosiderin deposits were observed in the cytoplasm of variable numbers of neoplastic cells. An expansile rather than infiltrative growth into superficial subcutis was also noted. No vascular/ Perineural invasion was seen. Both cases were consistently negative for S100, CK-AE1/AE3 and desmin. Focal positivity for CD68 and CD10 was seen. Conclusion: We report here on two cases of an uncommon histological subtype of AFX, for which we advocate use of the term “aneurysmal”. Correct identification of this uncommon AFX variant is essential in order to avoid its misdiagnosis as an aggressive neoplasm such as melanoma.


Atypical Fibroxanthoma; Immunohistochemistry; Pathology; Tumor; Sarcoma


Vallejo-Benítez A, Rodríguez-Zarco E, García-Castro R, Macías-García L, Pérez-Pérez M, Santos-Briz A, et al. Aneurysmal Atypical Fibroxanthoma. A Clinical Mimicker of Nodular Malignant Melanoma: Report of Two Cases and Review of the Literature. Ann Clin Case Rep. 2021; 6: 1951..

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