The patient developed brain metastasis 3 months after surgery and subsequently responded well to targeted therapy with the ALK inhibitor alectinib.<h4>Conclusions</h4>Our findings indicate that ALK-rearranged mesenchymal neoplasms with fibrosarcoma-like features, particularly those associated with elevated mitotic activity or tumor necrosis, should be classified as high grade in pathology reports. The gene discussed is ALK; the disease is fibrosarcoma.