Evaluation of pan-TRK immunohistochemistry in infantile fibrosarcoma, lipofibromatosis-like neural tumour and histological mimics.

Diffuse pan-TRK immunoreactivity is a highly sensitive but not entirely specific diagnostic marker for infantile fibrosarcoma, and may be helpful in selecting patients for TRK-targeted therapy. As expected, lipofibromatosis-like neural tumours, which harbour NTRK1 fusions, also show diffuse pan-TRK immunoreactivity.