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 case of an 11 - year - old boy is reported who was known to have Fanconi ' s anemia for 3 years and was treated with androgens , corticosteroids and transfusions .
### Output Text:
The case of an 11 - year - old boy is reported who was known to have Fanconi ' s anemia for 3 years and was treated with <span class="chemical">androgens</span> , <span class="chemical">corticosteroids</span> and transfusions . 