Aberrant Melan-A expression in atypical fibroxanthoma and undifferentiated pleomorphic sarcoma of the skin
Article first published online: 3 NOV 2011
Copyright © 2011 John Wiley & Sons A/S
Journal of Cutaneous Pathology
Volume 38, Issue 12, pages 954–960, December 2011
How to Cite
Thum, C., Hollowood, K., Birch, J., Goodlad, J. R. and Brenn, T. (2011), Aberrant Melan-A expression in atypical fibroxanthoma and undifferentiated pleomorphic sarcoma of the skin. Journal of Cutaneous Pathology, 38: 954–960. doi: 10.1111/j.1600-0560.2011.01798.x
- Issue published online: 3 NOV 2011
- Article first published online: 3 NOV 2011
- Accepted for publication July 6, 2011
- soft tissue tumors
Background: Atypical fibroxanthoma (AFX) is a distinctive clinicopathologic entity presenting on sun-damaged skin of the elderly. Its behavior is benign if strict diagnostic criteria are applied. Tumors showing invasion of deeper structures or perineural/lymphovascular invasion are best regarded as undifferentiated pleomorphic sarcoma of the skin. The diagnosis requires immunohistochemical studies to exclude melanoma, squamous cell carcinoma, angiosarcoma and leiomyosarcoma.
Methods: Two AFX and one undifferentiated pleomorphic sarcoma showing aberrant expression of Melan-A were identified. Clinical data were obtained and histopathological features, immunohistochemical profile and electron microscopy were assessed.
Results: All tumors arose on sun-damaged skin of elderly males. Two AFX showed pushing growth into superficial subcutis only. The undifferentiated pleomorphic sarcoma was characterized by infiltrative growth into galea as well as perineural invasion. Multifocal expression of Melan-A and MART-1 was largely limited to tumor giant cells in the absence of S100 or HMB-45 labeling. No melanosomes or premelanosomes were identified by electron microscopy.
Conclusions: Aberrant expression of Melan-A and MART-1 in AFX and undifferentiated pleomorphic sarcoma of the skin represents an important diagnostic pitfall with potential for misdiagnosis as melanoma. Melan-A expression limited to tumor giant cells, in the absence of S-100 positivity, is a helpful diagnostic feature.
Thum C, Hollowood K, Birch J, Goodlad JR, Brenn T. Aberrant Melan-A expression in atypical fibroxanthoma and undifferentiated pleomorphic sarcoma of the skin.