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: To our knowledge , this is the first report of a pseudo - allergy caused by paramethasone .
### Output Text:
To our knowledge , this is the first report of a pseudo - allergy caused by <span class="chemical">paramethasone</span> . 