In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: The results of skin lesion biopsies were available in 3 patients , confirming LV Cutaneous lesions resolved in all patients after warfarin was discontinued .
### Output Text:
The results of skin lesion biopsies were available in 3 patients , confirming LV Cutaneous lesions resolved in all patients after <span class="chemical">warfarin</span> was discontinued . 