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MITF positivity in atypical fibroxanthoma: a diagnostic pitfall
Ben Tallon1, Trevor W Beer, Trevor M Beer
1*Dermatopathology division, Pathlab Bay of Plenty, Tauranga; Da Vinci Clinic, Tauranga, New Zealand; and †Clinipath Pathology, West Perth, Australia.
The American Journal of Dermatopathology
|September 20, 2014
Summary
Microphthalmia transcription factor (MITF) can be positive in atypical fibroxanthoma (AFX), a finding not previously reported. Awareness of this aberrant MITF staining is crucial to prevent misdiagnosis of melanoma.
Area of Science:
- Oncology
- Dermatopathology
- Molecular Pathology
Background:
- Microphthalmia transcription factor (MITF) is a recognized melanocytic marker with high specificity.
- Aberrant expression of MITF has been observed in various tumors.
- Previous reports have not documented MITF positivity in atypical fibroxanthoma (AFX).
Purpose of the Study:
- To report the novel finding of MITF positivity in atypical fibroxanthoma (AFX).
- To highlight the importance of recognizing MITF expression in AFX to avoid misdiagnosis.
- To investigate MITF staining in nonneural granular cell tumors and their potential overlap with AFX.
Main Methods:
- Retrospective analysis of 11 cases of atypical fibroxanthoma (AFX) from two laboratories.
- Immunohistochemical staining for MITF was performed on all cases.
- Review of relevant literature on MITF expression in tumors.
Main Results:
- Eleven cases of AFX demonstrated positive MITF staining.
- Two cases of nonneural granular cell tumors also showed positive MITF staining.
- This aberrant MITF expression in AFX has not been previously documented.
Conclusions:
- MITF positivity can occur in atypical fibroxanthoma (AFX).
- Recognition of MITF expression in AFX is essential for accurate diagnosis and to rule out melanoma.
- The findings suggest a potential overlap between granular cell tumors and the granular subtype of AFX.
