Southside's pathologists are essential in diagnosing cancer, determining its stage or extent, and in identifying types of tumors. In addition to other diagnostic tools, Southside's Pathology Department uses a variety of techniques to interpret tissue samples such as sentinel node biopsy, which lets doctors and pathologists check lymph nodes near tumors for evidence that cancer has spread.

Pathologists uses a real-time telepathology computer system to view slides with their colleagues at participating North Shore-LIJ hospitals in consultation on complex or unusual cases.