Background: Desmoplastic malignant melanoma (DMM) is an uncommon variant of malignant melanoma and often is difficult to diagnose. Because of the relative rarity of this tumor, it has not been well studied and controversy remains concerning its biologic potential.
Objective: We compared survival rates of DMM with those of other malignant melanomas and determined what clinical and/or histologic features, if any, correlated with survival.
Methods: The files of the Armed Forces Institute of Pathology were searched for cases of DMM or related tumors with adequate material for further histologic and immunohistochemical evaluation. Follow-up on each patient was requested from the pathologist, clinician, and/or the patient. The follow-up was correlated with the histologic findings in each case. The relationship of histologic features to disease-free survival was evaluated.
Results: Adequate material for evaluation was available in 128 cases. The overall histologic features were similar to those previously reported. Immunohistochemical studies showed that all lesions were negative for HMB-45, a marker for premelanosomes. Factors that correlated with survival included tumor location, sex, tumor depth, and the presence of stromal mucin. The 5-year disease-free survival rate was 68% for all cases and 61% for lesions more than 4 mm deep.
Conclusion: With a 5-year disease-free survival rate of 61%, DMM has a significantly better prognosis than other melanomas that have a 5-year disease-free survival rates of 40% to 41%. This may be related to neural differentiation of these tumors.