The cell organelle that is most likely malfunctioning in the patient's body cell is the LYSOSOME. In animals, including humans, lysosomes is responsible for destroying worn off organelles, removing wastes and protecting cells from invaders. If the lysosome is malfunctioning, wastes will not be remove from the cell and this will lead to build up of wastes.
In plant cells, the vacuole is responsible for removing wastes from the cell.