Final answer:
The red/purple/black lesions around the injection sites in a patient receiving heparin injections are likely petechiae, which are caused by blood leaking out of damaged vessels. This can be due to Type III hypersensitivity, an immune-complex reaction.
Step-by-step explanation:
The red/purple/black lesions around the injection sites in a patient receiving heparin injections are likely petechiae. Petechiae are small red or purple spots on the skin that result from blood leaking out of damaged vessels. These lesions can occur due to a condition called Type III hypersensitivity, which is an immune-complex reaction. When soluble antigens bind with IgG in a certain ratio, immune complexes accumulate and cause localized reactions.