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: Case reports of 11 patients with severe , extensive localized scleroderma who were treated with D - penicillamine are summarized in this article .
### Output Text:
Case reports of 11 patients with severe , extensive localized scleroderma who were treated with <span class="chemical">D - penicillamine</span> are summarized in this article . 