Sentinel lymph node biopsy shows 9% positivity rate in patients with desmoplastic melanomaSentinel Lymph Node Biopsy Shows Specific Results for Desmoplastic Melanoma

BACKGROUND: The propensity of desmoplastic melanoma (DM) to spread to regional lymph nodes remains disputed, creating uncertainty regarding the role of sentinel lymph node biopsy (SLNB). This is further complicated by challenges in distinguishing pure from mixed histologic subtypes. We evaluated pooled SLN positivity rates for both subtypes to clarify the utility of SLNB in the workup of patients with DM. METHODS: Two databases (PubMed and Ovid MEDLINE) were searched through July 2025. We included studies in which at least a subset of patients with DM underwent SLNB and SLNB positivity rates could be ascertained; large registry-based studies were excluded. Our primary outcome was the pooled sentinel lymph node positivity rate for patients with DM. We performed a subgroup analysis to determine pooled SLN positivity by histologic subtype. RESULTS: We included 18 studies with 1671 patients with DM. A random-effects meta-analysis demonstrated a pooled SLN positivity rate of 9% (95% CI, 7-12%). No significant association was found between positivity and Breslow depth (β = 0.058, p = 0.749) or ulceration (β = 0.763, p = 0.677). Ten studies reported subtype-specific rates. The pooled positivity rate was 6% (95% CI, 4-8%) for pure DM and 15% (95% CI, 10-20%) for mixed DM. CONCLUSIONS: Patients with mixed DM may derive greater prognostic and diagnostic benefit from SLNB, whereas SLNB in pure DM may be considered selectively, particularly in the setting of histopathologic uncertainty or other high-risk features.