Background. Nodular histotype represents the condition that is mostly associated with diagnosis of thick melanoma.

Objective. The objectives were to evaluate variables associated with and pattern of detection of nodular melanomas and to investigate variables associated with early diagnosis in accordance with histotype (nodular vs. superficial spreading melanomas).

Methods. From the original data set of 816 melanomas, all the invasive lesions classified as superficial spreading (n=500) and nodular (n=93) melanomas were considered for the study. A multivariate logistic analysis was performed.

Results. Nodular melanomas did not significantly differ from superficial spreading melanomas regarding sex, anatomic site, number of whole-body nevi, and the presence of atypical nevi. As expected, nodular melanomas were represented by a higher percentage of thick (>2 mm) lesions compared to superficial spreading melanomas (64.5% vs. 9.6%, p<0.001). The pattern of detection significantly differed between nodular and superficial spreading melanomas, the former being more frequently self-detected (44.1% vs. 38.0%) or detected by the family doctor (34.4% vs. 11.4%). Female sex, high level of education, and detection made by a dermatologist had an independent, protective effect against late (>1 mm in thickness) diagnosis in superficial spreading melanomas. No protective variable associated with nodular melanomas was found.

Conclusion. Patterns of detection for nodular melanomas significantly differ from those for superficial spreading melanomas. For superficial spreading, but not for nodular, melanomas, variables associated with protective effect against late diagnosis can be identified.