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: All the lesions in dentate , inferior colliculus , pons , and medullas had been resolved completely on follow - up MRIs in 5 patients , but in 1 patient of them , corpus callosal lesion persisted .
### Output Text:
All the lesions in dentate , inferior colliculus , pons , and medullas had been resolved completely on follow - up MRIs in 5 patients , but in 1 patient of them , corpus callosal lesion persisted . 