Mediastinal lymph node distribution, size and number: definitions based on an anatomical study.

OBJECTIVE To create a reference map of mediastinal lymph nodes through the analysis of their size, number and distribution in various lymph node stations. METHOD A total of 50 cadavers, 38 males and 12 females, were studied. Of those 50, 39 were Caucasian. The mean age was 59.9 +/= 14.1 years, the mean height was 173.1 +/= 7.6 cm, and the mean weight was 71.0 +/= 12.0 kg. A bilateral mediastinal dissection was performed in order to resect and isolate all lymph nodes. The area, as well as the major and minor transverse diameters, of each lymph node was determined by radiographic imaging analysis. RESULTS In a sample of 485 chains, 1742 lymph nodes were dissected (2.58 +/= 1.89 lymph nodes/station), revealing a mean number of 21.2 +/= 8.5 lymph nodes on the right and 13.6 +/= 6.3 on the left. The lymph node stations 1, 2R, 4R, 5, and 7 were present in more than 90% of the sample. Only the 4R and 7 lymph node stations were always present. The lymph node stations 2L, 3p, and 8 were present in 32, 36, and 54% of the sample, respectively. Mediastinal lymph nodes were present in greater numbers in the 2R, 4R and 7 lymph node stations. In addition, these stations presented the largest mediastinal lymph nodes. CONCLUSION Composing a reference map for lymph node sizes was feasible. No alterations were observed in the distribution, number, or size of lymph nodes in the age brackets studied, regardless of gender, race, weight, or height.