Ultrasound showing an<unk>  of the skin thumb An<unk>  is a localized collection of pus (purulent inflammatory tissue) caused by suppuration buried in a tissue, an organ, or a confined space, lined by the pyogenic membrane. Ultrasound imaging can help in a diagnosis. Classification<unk> es may be classified as either skin<unk> es or internal<unk> es. Skin<unk> es are common; internal<unk> es tend to be harder to diagnose, and more serious. Skin<unk> es are also called cutaneous or subcutaneous<unk> es. IV drug use For those with a history of intravenous drug use, an X-ray is recommended before treatment to verify that no needle fragments are present. If there is also a fever present in this population, infectious endocarditis should be considered. Differential<unk> es should be differentiated from empyemas, which are accumulations of pus in a preexisting, rather than a newly formed, anatomical cavity. Other conditions that can cause similar symptoms include: cellulitis, a sebaceous cyst, and necrotising fasciitis. Cellulitis typically also has an erythematous reaction, but does not confer any purulent drainage.
Abscess
Necrotizing fasciitis
Dilaceration
Cellulitis
Joint effusion
Sebaceous cyst
Thrombus
Phlegmon