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: SUMMARY : A 63 - year - old Caucasian man with renal amyloidosis undergoing peripheral blood stem cell collection for an autologous stem cell transplant developed extensive bilateral upper - extremity deep venous thrombosis ( DVT ) and pulmonary embolism secondary to heparin - induced thrombocytopenia .
### Output Text:
SUMMARY : A 63 - year - old Caucasian man with renal amyloidosis undergoing peripheral blood stem cell collection for an autologous stem cell transplant developed extensive bilateral upper - extremity deep venous thrombosis ( DVT ) and pulmonary embolism secondary to <span class="chemical">heparin</span> - induced thrombocytopenia . 