Objective  Sentinel node lymphoscintigraphy and biopsy is an essential procedure in theranostics of skin tumors.The aim of this study is to determine the role of SPECT/CT in localization of sentinel lymph node of skin tumors.

  Methods  This study retrospectively reviewed the sentinel node lymphoscintigraphy and biopsy data in patients with skin tumors diagnosed in Peking Union Medical College Hospital from April 2019 to February 2023, and analyzed the role of SPECT/CT in sentinel lymphoscintigraphy.

  Results  Thirty-seven patients were retrospectively enrolled.The primary skin tumor included melanoma (32 patients), squamous cell carcinoma (3 patients), and basal cell carcinoma (2 patients).The sentinel nodes localized in inguinal (23 patients), popliteal (2 patients), axilla (8 patients), trochlea (2 patients), and parotid/periauricular regions (2 patients).Sentinel lymph nodes were localized by SPECT/CT in 36 cases (one patient only underwent planar dynamic imaging).SPECT/CT detected multiple focus in the lymphatic drainage in 16 patients, and in 13 patients they were confirmed to be local retention of the tracer in the lymphatic duct instead of the sentinel lymph node, suggesting false positive uptake.Thirty-four patients underwent sentinel node biopsy 1-4 h after localization, and localization of the sentinel node was consistent with preoperative sentinel node lymphoscintigraphy.Sentinel node biopsy found nodal metastasis in 6 patients (all of them had melanoma in the foot or lower limb).

  Conclusions  Sentinel node lymphoscintigraphy is an important step for localization before sentinel node biopsy.SPECT/CT can help improve the accuracy of localizing sentinel lymph node.