Sentinel lymph node metastasis in primary cutaneous basosquamous carcinoma. A cross-sectional study.

BACKGROUND AND OBJECTIVES: Basosquamous carcinoma (BSC) is a rare, biologically aggressive tumor. This cross-sectional study aims to define risk factors for subclinical nodal metastasis in primary BSC, and identify the patients who would benefit from routine sentinel node biopsy (SLNB) as part of the initial management. METHODS: A total of 142 patients, with histologically proven BSC without palpable lymph nodes, underwent SLNB after the initial excision. Clinicopathological features and demographics were analyzed between the patients with detected micrometastasis (SLNM) and those with negative SLN. RESULTS: In 7.7% patients, subcapsular and <0.1 mm SLNM were found. The frequency of SLNM was 0.9%, 11.8%, and 80.0% in patients with maximum lesion diameter ≤ 2 cm, 2.1-3.0 cm and >3.0 cm, respectively (P < 0.001) and was strongly associated with perineural (P < 0.001; OR = 26.46, 95% CI = 5.62-124.52) and lymphatic invasion (P < 0.001; OR = 17.35, 95% CI = 4.44-67.91). Within 18-84 months, no recurrence or metastasis were observed in SLNM positive patients. False negative SLNB rate of 15.4% was recorded. CONCLUSION: Cutaneous BSC is associated with early nodal metastatic potential. Tumor size >2 cm, lymphatic and perineural invasion are significant determinants for SLN micrometastasis. In the absence of palpable lymphadenopathy, wide resection and SLNB with long-term follow-up are highly recommended in these patients.