Lymphedema is a chronic disease that affects patients’ quality of life. Vascularized groin lymph node transfer is a reliable treatment that requires detailed anatomic knowledge of the superficial inguinal lymph nodes (SILNs). This study compared the anatomy of SILNs between patients with upper-extremity lymphedema and individuals without lymphedema using pelvic computed tomography (CT).

The CT scans of 17 patients (the patient group) with upper-extremity lymphedema and 34 individuals without lymphedema (the normal group) were studied. The reference point was marked 3 cm perpendicularly below one-third of the line from the pubic tubercle to the anterior superior iliac spine. The number, distance, and concentration of SILNs were measured relative to the reference point.

The SILNs in the normal group had a mean count of 6.47±1.19, a mean distance from the reference point of 21.10±9.66 mm, and a mean concentration of 84%. The patient group had a mean lymph node count of 7.68±1.63, a mean distance of 22.48±9.51 mm, and a mean concentration of 77%. The normal and patient groups had significantly different mean lymph node counts (p=0.01). The mean distance from the reference point (p=0.07) and the mean lymph node concentration (p=0.20) did not differ significantly between groups.

Pelvic CT is a reliable method to evaluate the anatomy of SILNs in detail. A statistically significant difference was found in the number of lymph nodes between the lymphedema patient group and the normal group, but not in their distribution.

Lymphedema is a chronic disease that affects patients’ quality of life. The incidence of breast cancer-related lymphedema ranges from 6% to 30% [

To date, SILNs are known to be concentrated 3 cm perpendicular to one-third of the line from the pubic tubercle (PT) toward the anterior superior iliac spine (ASIS) [

Various factors, including obesity, radiation, postoperative infection, and genetic factors, increase the risk of lymphedema [

This study retrospectively analyzed patients with upper-extremity lymphedema who underwent VGLNT from January 2015 to December 2020 by a single surgeon (DWK). Eighty patients with lymphedema who visited the Korea University Ansan Hospital were included. Patients who had upper-extremity lymphedema after breast cancer surgery and had undergone a preoperative contrast-enhanced pelvic CT were included. Patients with a history of other cancers and inguinal operations were excluded. Patients with a history of postoperative infection after breast surgery were also excluded because it is a known risk factor for lymphedema and could have affected our results [

After applying the inclusion and exclusion criteria, 17 patients with upper-extremity lymphedema were included. Thirty-four controls were selected as the normal group from the healthy individuals who had pelvic CT for regular medical checkups without related diagnosis and lymphedema and had characteristics similar to the patient group. For an accurate comparison, we have matched age, body mass index (BMI), and smoking history between the patient group and the normal group.

After the patients with lymphedema (comprising the patient group) and individuals without lymphedema (comprising the normal group) were selected, their CT scan results were evaluated. First, the number of lymph nodes was counted. On the coronal view, a line was drawn between the ASIS and PT, which coincided with the inguinal ligament. The SILNs inferior to the inguinal ligament were counted and marked (

A reference point was marked 3 cm perpendicularly below one-third of the line from the PT toward the ASIS (

The coordinates of each lymph node were obtained by defining the inguinal ligament line as the ‘X’ axis and a line perpendicular to this as the ‘Y’ axis (

The normality test results were unsatisfactory because of the small number of patients. Hence, the Mann-Whitney U-test was used to compare the number of lymph nodes and their distance from the reference point between groups. The chi-square test was used to compare the percentage of lymph nodes within the 3-cm boundary of the reference point between the groups. The following statistical tests were used to compare patient characteristic variables between the groups: the t-test for age, the Mann-Whitney test for BMI, the Fisher exact test for smoking, and the Pearson chi-square test for chemotherapy history. All statistical analyses were conducted using the SPSS software ver.10 (SPSS Inc., Chicago, IL, USA). The level of statistical significance was set at p<0.05.

We compared the pelvic CT images of 17 patients with lymphedema with those of 34 individuals without lymphedema. There were no significant differences in most demographic measures between the two groups, except for the chemotherapy history (

Before comparing the patient and normal groups, we compared the patients’ left and right inguinal lymph nodes. The mean number of lymph nodes on the left side was 7.88±1.97 and on the right side was 7.47±1.19. The mean distance of the left-side lymph node from the reference point was 22.65±9.79 mm, and the percentage within the boundary was 77%. The mean distance of the right side from the reference point was 22.29±9.20 mm, and the percentage within the 3-cm boundary was 78% (

After determining that there was no significant difference between the left and right sides in patients with lymphedema, we compared the patient and normal groups. The mean number of lymph nodes in the normal group was 6.47±1.19, the mean distance of the lymph node from the reference point was 21.10±9.66 mm, and the percentage of lymph nodes within the 3-cm boundary was 84%. The mean number of lymph nodes in the patient group was 7.68±1.63, the mean distance of the lymph node from the reference point was 22.48±9.51 mm, and the percentage of lymph nodes within the 3-cm boundary was 77% (

Although VGLNT is an effective treatment modality for lymphedema, it has not been widely used because of concerns regarding donor-site iatrogenic lymphedema [

Bontumasi et al [

To avoid iatrogenic lymphedema and increase the success rate, anatomical studies on SILN have been conducted [

In our study, 80% of the SILNs were distributed in a 3-cm boundary, which correlates with previous studies. Dayan et al. [

Obesity, radiation, postoperative infection, and even genetic factors are considered significant risk factors for developing secondary lymphedema [

This study has several limitations. First, the sample size was small. The results could be different if more patients were studied. Second, most of the patients had breast cancer surgery at other hospitals, and we could not obtain detailed information about the patients’ preoperative conditions or the type of breast surgery they had undergone.

There was no significant difference in the distribution of lymph nodes between the two groups, as evaluated by distance and percentage factors. There was a considerable difference in the number of lymph nodes between the two groups (p<0.05). We only could be less concerned about SILN insufficiency when progressing to VGLNT. However, since the detailed knowledge of the functional mechanisms of VGLNT is unknown, it is difficult to conclude the difference in the number of lymph nodes could have a clinical impact. In addition, we can use knowledge from previous anatomic studies, regardless of whether the target group is a patient or a normal group [

We could ascertain the detailed anatomy of SILN using CT; hence, we recommend the examination during the preoperative preparation for VGLNT. This study revealed a significant difference in the number of LNs, but no significant difference in the distribution of LNs between the normal and patient groups.

The authors have nothing to disclose.

None.

Coronal view of contrast-enhanced pelvic computed tomography. A line was drawn between the anterior superior iliac spine (ASIS) and pubic tubercle (PT), which coincided with the inguinal ligament (white line). Superficial inguinal lymph nodes were marked with red circles and those inferior to the inguinal ligament were counted.

A reference point was marked on a point 3 cm inferior and perpendicular to the middle one-third of the line drawn from the pubic tubercle (PT) to the anterior superior iliac spine (ASIS).

The distance from a lymph node (LN) to the reference point was calculated using the Pythagorean theorem. (A) The coordinates of each LN were obtained by defining the inguinal ligament line as the X-axis and a line perpendicular to this as the Y-axis. (B) The image is rotated for a better understanding of the X-axis and Y-axis. (C) The Pythagorean theorem is used. (D) The distance from the reference point to the lymph nodes was calculated using this formula. ASIS, anterior superior iliac spine; PT, pubic tubercle.

Based on the distance calculated previously, the percentage of lymph nodes within a 3-cm boundary from the reference point was calculated. ASIS, anterior superior iliac spine; PT, pubic tubercle.

Characteristics of the patient and normal groups

Characteristic | Patient group | Normal group | p-value |
---|---|---|---|

No. of patients | 17 | 34 | |

Age (yr) | 51.0±8.2 | 51.4±6.4 | 0.51 |

Female sex | 17 (100) | 34 (100) | - |

Body mass index (kg/m^{2}) |
25.4±2.7 | 23.5±4.0 | 0.07 |

Smoking | 3 (17.6) | 5 (14.7) | 0.69 |

Chemotherapy history | 12 (70.6) | 0 (0) | <0.01 |

Values are presented as mean±standard deviation or number (%).

LN comparison between the ipsilateral and contralateral sides

Variable | Ipsilateral side | Contralateral side | Total | p-value |
---|---|---|---|---|

No. of LNs | 7.88±1.97 | 7.47±1.19 | 7.67±1.66 | 0.74 |

Distance of LNs (mm) | 22.65±9.79 | 22.29±9.20 | 22.48±9.53 | 0.78 |

Concentration (% of LNs within the 3-cm boundary) | 77 | 78 | 77 | 0.83 |

Values are presented as mean±standard deviation or percentage only.

LN, lymph node.

Comparison of LNs between the normal and patient groups

Variable | Normal group | Patient group | Total | p-value |
---|---|---|---|---|

No. of LNs | 6.47±1.19 | 7.68±1.63 | 6.87±1.48 | 0.01^{*} |

Distance of LNs (mm) | 21.10±9.66 | 22.48±9.51 | 21.61±9.63 | 0.07 |

Concentration (% of LNs within the 3-cm boundary) | 81 | 77 | 80 | 0.20 |

Values are presented as mean±standard deviation or percentage only.

LN, lymph node.

^{*}Statistically significant.