Sentinel Node Biopsy in Pediatric Patients: The Experience in a Single Institution

Abstract

Sentinel lymph node biopsy (SLNB) is an established staging technique in many malignancies, but reports describing this procedure for the evaluation of regional lymph nodes in childhood and adolescents are still scarce. SLNB has progressively gained a role in the staging of pediatric melanoma and some histotypes among soft tissue sarcomas (rhabdomyosarcoma, synovial sarcoma, epithelioid sarcoma, and clear cell sarcoma). We report our experience with 29 patients who were evaluated with SLNB during the past 12 years: 9 alveolar rhabdomyosarcoma, 1 embryonal rhabdomyosarcoma, 7 Ewing Sarcoma/pPNET, 1 clear cells sarcoma, 2 epithelioid sarcoma, 1 epithelioid sclerosing fibrosarcoma, 3 myxoid liposarcoma, 1 adult fibrosarcoma, 1 malignant peripheral nerve sheath tumor, 1 undifferentiated sarcoma, 1 sarcoma not otherwise specified, and 1 melanoma. All, but one, patients underwent a lymphoscintigraphy, and in more than half of the patients, an intraoperative lymphatic mapping with a blue dye injection was performed. In our experience, SLNB was a feasible and reliable technique that allowed a targeted sampling of regional lymph nodes. This technique avoids aggressive operations or random biopsies, leading to an accurate staging without complications. Recently new imaging techniques, such as positron emission tomography-computed tomography scan, have obtained good results in identifying distant and lymphatic metastases, but they have been found to be less reliable than SLNB, especially for small volume metastatic nodal disease in sarcoma.

Detection of lymph node metastases in pediatric and adolescent/young adult sarcoma: Sentinel lymph node biopsy versus fludeoxyglucose positron emission tomography imaging—A prospective trial

“…Our study confirms previous reports of the feasibility and safety of performing SLNB in pediatric and AYA sarcoma patients . Contemporary cooperative group protocols now require nodal sampling for patients with extremity rhabdomyosarcoma even without clinical or radiographic evidence of nodal metastasis because of the relatively high frequency of regional metastases and the possibility that physical examination and cross‐sectional imaging may underestimate the presence of metastatic disease.…”

“…In the only published pediatric study comparing PET‐CT with SLNB in pediatric sarcoma patients, 3 of 8 patients had hypermetabolic regional nodes; this was consistent with metastases on PET‐CT, but only 1 was found to contain tumor on SLNB . In agreement with that smaller study, we have demonstrated that PET‐CT had a positive predictive value of only 29%, and this suggests that PET‐CT cannot be used exclusively for the identification of metastatic disease in the pediatric population and cannot be a substitute for tissue sampling . This finding cannot be explained by minimal tumor burden alone in the histologically positive nodes because there was no correlation between disease burden per the pathology report and PET‐CT detection.…”

“…15 In agreement with that smaller study, we have demonstrated that PET-CT had a positive predictive value of only 29%, and this suggests that PET-CT cannot be used exclusively for the identification of metastatic disease in the pediatric population and cannot be a substitute for tissue sampling. 13,19,25 This finding cannot be explained by minimal tumor burden alone in the histologically positive nodes because there was no correlation between disease burden per the pathology report and PET-CT detection. One of the metastatic sentinel nodes that was not detected on PET-CT had been replaced entirely by metastatic cells, whereas nodes with only small nests of microscopic disease were detected on PET-CT in 3 other patients.…”

“…Our study confirms previous reports of the feasibility and safety of performing SLNB in pediatric and AYA sarcoma patients. [13][14][15][24][25][26][27] Contemporary cooperative group protocols now require nodal sampling for patients with extremity rhabdomyosarcoma even without clinical or radiographic evidence of nodal metastasis because of the relatively high frequency of regional metastases and the possibility that physical examination and cross-sectional imaging may underestimate the presence of metastatic disease. The identification of nodal metastases is of critical importance because the accurate identification of nodal metastases can result in treatment modifications that may reduce the chance of subsequent recurrence.…”

Sclerosing Spindle Cell Preauricular Rhabdomyosarcoma in a 7-Year-Old Female

“…Sentinel lymph node biopsy is a reliable staging technique and yield positive results. It was positive most commonly associated with alveolar RMS, followed by Ewing sarcoma, myxoid liposarcoma, epitheloid sarcoma and positive in one patient with embryonal RMS out of 29 patients' studied [16].…”