A biopsy device comprises a handpiece, a fluid collection system, and a power transmission source. The handpiece is configured for grasping by a single hand, and is independently manipulatable by hand for movement of the instrument toward and away from the patient. An elongated piercer extends from the distal end of the handpiece. The piercer has a sharpened distal end for entering the tissue and a port located proximal to the sharpened distal end for receiving a portion of tissue mass. An elongated cutter is disposed coaxially relative to a piercer lumen of the piercer. A distal blade of the cutter slides distally past the port of the piercer to sever the tissue portion drawn into the port by vacuum. The handpiece further comprises a holster for detachably connecting a cutter rotational transmission and a cutter axial transmission to the power transmission source.