1. A medical image processing apparatus, comprising: a medical image obtaining unit that obtains a medical image representing a subject; an anatomical information extraction unit that extracts a lung field area from the obtained medical image; a depressed portion detection unit that compares a contour of the extracted lung field with a comparison contour obtained by causing an active curve, having an initial shape in the lung field area and repeats deformation according to a certain deformation trend, to converge after repeating the deformation and detects a depressed portion of the lung field; and a pleural plaque candidate detection unit that determines the detected depressed portion as a first pleural plaque candidate.