"Triple injection" lymphatic mapping technique to determine if parametrial nodes are the true sentinel lymph nodes in women with cervical cancer

Abstract

Objectives: Lymphatic mapping studies in women with cervical cancer typically identify sentinel nodes (SLNs) in the pelvis and not the parametrium. We added India ink as a mapping agent to determine whether this would allow us to pathologically identify sentinel parametrial nodes and to test our hypothesis that the parametrial nodes are the true SLNs in women with cervical cancer.

Methods: We performed lymphatic mapping and SLN biopsy in 20 women with early-stage cervical cancer undergoing radical hysterectomy or trachelectomy using a "triple injection" technique with blue dye, radiocolloid, and India ink. Pathologic processing of parametrium and nodal tissue was then performed to identify India ink in specimens.

Results: On pathology review, 15 (75%) patients had a parametrial node identified, and 9 patients (45%) had bilateral parametrial nodes identified; the median number of parametrial nodes identified was 2 (range, 0-7). India ink was seen in at least 1 parametrial node in 13 (87%) of the 15 patients with a parametrial node identified pathologically. Of the 9 patients with bilateral parametrial nodes identified pathologically, only 5 (54%) had bilateral parametrial nodes containing India ink. India ink was found in 26 (44%) of 59 SLNs and only 1 (0.3%) of 289 non-SLNs. In 5 patients, India ink was seen in a SLN on the same side of the pelvis where a parametrial node was identified but not microscopically black.

Conclusions: There appears to be direct drainage of cervical lesions to pelvic nodal basins bypassing small parametrial nodes. Parametrial nodes, therefore, may not always be the SLNs in women with cervical cancer.

Figure 1

Photomicrographs of parametrial lymph nodes from study cases: 1A) 1.0 mm lymph node representative of the small lymph nodes typically identified in sections of parametrium (10x); 1B higher power image of the same lymph node with focal India ink in the superficial cortex (arrow, 40x); 1C, parametrial lymph node with a < 1.0 mm focus of metastatic squamous cell carcinoma (arrows, 10x); 1D, very small focus of India ink present in the superficial cortex adjacent to the metastasis (arrow, 40x).