[Cytology of fluids of articular puncture]

Cytologic examination of synovial fluid has been shown to be useful in the diagnosis of various joint diseases. Few pathologists are proficient in the interpretation of the occasional synovial fluids that most cytology laboratories receive. The majority of the aspirated synovial fluids are sent only for bacterial culture and valuable information from the cytologic examination is missed. We describe how pathologists should perform analysis of these fluids and what kind of information they can provide to the physician.