Poster Presentation Australasian Melanoma Conference 2026

Nodular melanoma versus superficial spreading melanoma: a comparative analysis of clinicopathologic features and prognosis (#428)

Daniel D. Oh 1 2 3 , Serigne N. Lo 1 2 , Janet McKeown 1 , Richard A. Scolyer 1 2 4 5 , Omgo E. Nieweg 1 2 3 , Kerwin F. Shannon 1 2 3 6 , Andrew J. Spillane 1 2 6 7 , John F. Thompson 1 2 3 , Robyn P. M. Saw 1 2 3 6
  1. Melanoma Institute Australia, The University of Sydney, Sydney, New South Wales, Australia
  2. Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
  3. Department of Melanoma and Surgical Oncology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
  4. Department of Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital and NSW Health Pathology, Sydney, New South Wales, Australia
  5. Charles Perkins Centre, The University of Sydney, Sydney, New South Wales, Australia
  6. Mater Hospital, Sydney, New South Wales, Australia
  7. Department of Breast and Melanoma Surgery, Royal North Shore Hospital, Sydney, New South Wales, Australia

Background:
Nodular melanoma (NM) is considered a major contributor to melanoma-related mortality. Paradoxically, the Melanoma Institute Australia Prediction Tool for sentinel lymph node metastasis risk assigns a lower risk of sentinel node positivity to NM compared with superficial spreading melanoma (SSM) when other clinicopathologic predictors are comparable. This study compared the clinicopathologic characteristics and prognosis of NM with SSM.

 

Methods:
A retrospective analysis was conducted of patients diagnosed with primary nodular or superficial spreading melanoma between 1 January 1985 and 31 December 2015 from the Melanoma Research Database. The study period was selected to exclude the impact of systemic therapy on survival outcomes. Data collected included demographics, tumour characteristics, primary site, sentinel lymph node biopsy (SLNB) status, history of lymphadenectomy, and survival outcomes.

 

Results:
In total 7,649 patients were included (3,135 NM; and 4,514 SSM).

 

NM demonstrated more aggressive pathological features than SSM, including greater median Breslow thickness 2.9 mm (range 0.3–50.0 mm) versus 0.9 mm (range 0–27.5 mm), and higher median mitotic rate 5/mm2 (range 0–98) versus 1/ mm2 (range 0–45). Ulceration was more common in NM (49.3%) compared to SSM (14.0%). SLNB positivity was similar for NM (26.5%) and SSM (24.5%).

 

On univariate analysis, NM was associated with worse overall survival (OS) than SSM (HR 0.46, 95% CI 0.43–0.49, p<0.001). This difference remained significant on multivariable Cox analysis adjusting for age, sex, Breslow thickness, primary site, SLNB status, and history of lymphadenectomy (HR 0.74, 95% CI 0.69–0.80, p<0.001). Similar findings were observed for disease-free survival (univariate HR 0.45, 95% CI 0.43-0.48, p<0.001; multivariable HR 0.65, 95% CI 0.61-0.69, p<0.001).

 

Conclusions:
NM patients presenting to Melanoma Institute Australia have more aggressive clinicopathologic features and poorer survival outcomes than those with SSM. Despite this they have similar rates of sentinel node positivity. This discordance highlights the need for further research into the molecular, genetic, and biological mechanisms underlying the aggressive behaviour of NM. In addition, the impact of contemporary systemic therapies on survival outcomes for each melanoma subtype warrants further study.