A cytology sampling system includes a catheter tube and a cytology tool. The catheter tube has open proximal and distal ends. The cytology tool is insertable through the catheter tube and includes a flexible shaft, a brush, and a position sensor. The brush is coupled to a distal end of the flexible shaft. The brush includes a plurality of brush shafts. Each brush shaft has bristles disposed along a portion of a length thereof. The bristles are coupled to and extend radially away from an outer surface of each of the brush shafts. The bristles are configured to collect cell samples from targeted tissue of a patient. The position sensor provides an indication of the location of the position sensor within a luminal structure. The system may include a positioning assembly for placing the distal end of the catheter tube adjacent the target tissue.