Figure 5. Normal variation in thymic appearance from the first edition (in 1945) of Pediatric X-Ray Diagnosis by Caffey. Original arrows demonstrate some of the variations in thymic size and configuration. Before Caffey emphasized this normal variation, thymic appearances on radiographs similar to these were implicated in cases of sudden infant death, particularly from status thymicolymphaticus. (Reprinted, with permission, from reference 36.)