Figure 3.

Four ways in which the FMA differs in specificity from ICD-O codes. (A) Examples of ICD-O codes that correspond to FMA classes consisting of a wall and lumen (an anatomical space). Neoplasms can arise only from the wall. (B) Several ICD-O codes refer to general types of structures, such as laryngeal cartilages. The FMA provides classes for both the type of structure and the specific structures. (C) Some structures such as the urethra and breast display significant sexual dimorphism. The FMA provides separate female and male classes for these structures. (D) For bilateral structures, the FMA provides classes for left and right. (In ICD-O this information is coded separately, allowing right, left, unilateral but unknown, and bilateral sites to be specified.)