Background. Desmoplastic melanomas with and without neurotropism are thought to be more clinically aggressive than other melanomas of comparable thickness. This study evaluates the prognostic significance of desmoplasia and neurotropism in Patients with Stage I cutaneous melanoma completely excised at the initial presentation of disease and prospectively studied for a minimum of 8 years.
Methods. Desmoplasia and neurotropism were evaluated as single prognostic predictors in survival outcome of cutaneous Stage I melanomas and as variables in the University of Pennsylvania Pigmented Lesion Study Group 8-year survival model for Stage I melanoma. In addition, the clinical presentation and follow-up of melanomas with desmoplasia and/or neurotropism was compared with that of other types of cutaneous Stage I melanoma in patients also followed for a minimum of 8 years.
Results. Neurotropism was associated with a statistically significant decrease in survival in patients with melanomas with desmoplasia. A decrease in survival also was observed in other types of melanoma with neurotropism, but the difference was not statistically significant. Melanomas with neurotropism had a statistically significant increase in local recurrence. Desmoplasia was not associated with a statistically significant decrease in survival.
Conclusion. Desmoplasia is not associated with a statistically significant decrease in the prognosis of patients with primary cutaneous Stage I melanoma. The more clinically aggressive behavior of desmoplastic melanomas observed in previous studies may be secondary to initial misdiagnosis and/or inadequate margin assessment of these lesions. Neurotropism, however, is associated with a statistically significant decrease in survival in patients with desmoplastic melanomas and is most likely associated with decreased reduces patient survival in other melanoma types. Neurotropism is also related to an increase in the frequency of local recurrence of melanoma. Cancer 1995; 76:2242–7.