CBC
ESR
Ultrasound
Xray
Generally a clinical diagnosis, based on history and physical exam
Labs generally show elevated WBC and inflammatory markers
Xray is done to rule out radiopaque foreign body
Flexor tenosynovitis
Bed bugs
Medial epicondylitis
Closed fist infection 
Lateral epicondylitis
Digital Mixoid Cyst 
Olecranon bursitis 
Hand cellulitis