Characteristics of intestinal-related lymphoid hyperplasia in children and its correlation with intussusception of children
Authors: Yan Qingtao , Xu Liandi , Chao Jun , Zhang Zemin , Wang Hui 
Published: November 2022

Abstract
Background
Primary intussusception in children is a common acute abdominal disease. The cause of this disease is still not fully understood. Many articles have reported that children with intussusception are often accompanied by hyperplasia of mesenteric lymph nodes and submucosal lymphoid tissue of the terminal ileum. Therefore, hyperplasia of intestinal-associated lymphoid tissue (mesenteric lymph nodes and submucosal lymphoid tissue of the intestinal tract) may be one of the main causes of intussusception. However, the characteristics and differences of intestinal-associated lymphoid tissues in healthy children and children with intussusception at different ages have not been reported. In addition, the relationship between mesenteric lymph nodes and intestinal submucosal lymphatic tissue also needs to be further understood.

Methods
73 patients with intussusception during the recovery phase who were treated in our hospital from October 2019 to October 2021 were collected as the observation group, while 101 children with healthy physical examination or diseases unrelated to intestinal lymphoid hyperplasia were collected as the control group. They were divided into different age groups of 1–6 months, 7–12 months, 13–18 months, 19–24 months, 25–36 months, 3–4 years, 5–6 years, and 7–8 years old. Ultrasonography was used to explore and scan mesenteric lymph nodes in fixed areas of the right lower abdomen and around the umbilicus. The size (cm3) and number (n) of detectable lymph nodes in each region were recorded and calculated, and the total mesenteric lymph node volume (cm3) of the right lower abdomen (RLTMLNV) and periumbilical region (PTMLNV) was calculated, respectively. The total mesenteric lymph node volume of each region in different ages of the two groups was analyzed.

Results
(1) There were significant differences between the control group and the observation group in the right lower abdominal total mesenteric lymph nodes volume (RLTMLNV) and the periumbilical total mesenteric lymph nodes volume (PTMLNV) (P = 0.001). The mesenteric lymph nodes in the observation group showed severe hyperplasia. (2) Children with intussusceptions are usually accompanied by severe mesenteric lymphoid hyperplasia. The mean volume value of RLTMLNV was greater than that of PTMLNV. Especially within 2 years of age, the mean value of RLTMLNV was significantly higher than that of PTMLNV with statistical significance (P < 0.05). (3) In normal children (control group), lymph nodes in the right lower abdomen and periumbilical area showed low hyperplasia, and there was a significant difference between age groups of < 2 years old and 2–8 years old (p = 0.001). In the children with intussusception (observation group), the hyperplasia of mesenteric lymph nodes in the right lower abdomen and around the umbilicus was severe. There was no significant difference in the proliferation of mesenteric lymphoid tissue among different age groups in the right lower abdomen (P = 0.834). There was also no significant difference in hyperplasia of periumbilical mesenteric lymphoid tissue among different age groups (P = 0.097).

Conclusions
Our research shows: (1) The occurrence of primary intussusception in children is related to the hyperplasia of intestinal-associated lymphoid tissue. (2) Children with intussusceptions were usually accompanied by severe mesenteric lymphoid hyperplasia. The mesenteric lymphoid hyperplasia was more evident in the right lower abdominal ileocecal area than in the periumbilical area before 2 years of age. RLTMLNV has better predictability of intussusception than PTMLNV. The occurrence of intussusceptions was more closely related to the hyperplasia of intestinal-associated lymphoid tissue in the right lower abdomen. (3) Normal children showed a low degree of mesenteric lymphoid hyperplasia before 2 years old, moderate hyperplasia after 2 years old, and mesenteric lymphoid hyperplasia in the right lower abdominal ileocecal area was basically the same as the periumbilical area. The lymphatic tissue of the right lower abdomen and periumbilical mesentery in children with intussusceptions showed severe hyperplasia, and there were no significant differences among different age groups.