Immunohistochemical Characteristics of Atypical Fibroxanthoma and Pleomorphic Dermal Sarcoma: A Systematic Review and Meta-Analysis.

Background: Differentiating atypical fibroxanthoma (AFX) from pleomorphic dermal sarcoma (PDS) remains a challenge. Increasing the use of immunohistochemistry has led to the proposal of many immunomarkers that may aid in the diagnosis of AFX and PDS. In this meta-analysis, we investigate the immunohistochemical characteristics of AFX and PDS based on suggested immunomarkers in the literature. Second, we identify potential distinctive markers found in the tumors' respective immunohistochemical profiles.

Methods: We included studies using immunomarkers on at least 10 consecutive patients with clinically and histopathologically verified AFX or PDS. The positive rates of the immunomarkers were pooled across the included studies with random-effects models. The immunomarkers were further categorized by a priori-chosen cutoffs in positive rates as positive markers (>90%) or negative markers (<10%). Differences between AFX and PDS were compared with Wald tests.

Results: We included 45 studies (1516 tumors) reporting on 35 immunomarkers. CD10 was positive in 94% (95% confidence interval, 87-99) of AFX cases and 100% (95% confidence interval, 99-100) of PDS cases. In accordance with the literature, both AFX and PDS were mainly negative for epithelial markers, melanocytic markers, markers of smooth muscle differentiation, and endothelial markers. None of the examined immunomarkers could distinguish AFX from PDS.

Conclusions: Our results suggest that CD10 is a useful positive immunomarker for both AFX and PDS. We found no difference in immunohistochemical profile when comparing AFX with PDS. Our analysis suggests that CD10, AE1/AE3, CK5/CK6, p63, S100, SOX10, desmin, SMA, CD31, and ERG could be used to differentiate AFX and PDS from other spindle cell neoplasms.