Background: Desmoplastic melanoma (DM) is a rare subtype of melanoma that is characterized by malignant spindle cells separated by prominent, fibrocollagenous stroma. Primary melanomas either may be entirely desmoplastic or almost entirely desmoplastic (pure DM [pDM]) or may exhibit a desmoplastic component admixed with a nondesmoplastic component (combined DM [cDM]).
Methods: Patients who were diagnosed between 1993 and 2007 at a single institution with clinically localized, primary cutaneous melanoma (PCM) that contained a desmoplastic component and who underwent sentinel lymph node (SLN) biopsy were identified. Clinical and pathologic features of the primary tumors were correlated with DM type, SLN status, and patient outcome.
Results: Two hundred fifty-two patients (167 men, 85 women) were identified (median age, 61 years). The median tumor thickness was 2.0 mm. One hundred twenty-three patients (48.8%) had pDM, and 129 patients (51.2%) had cDM. Overall, 17 patients (6.7%) had positive SLN status, including 12 patients with cDM and 5 patients with pDM. Because of the low SLN-positive rate, a statistically significant difference in SLN status between patients with cDM (8.5%) and patients with pDM (4.9%; P = .25) could not be demonstrated. Older patient age, being a man, positive SLN status, and increasing tumor thickness were associated significantly with poorer disease-free survival (P < .05), although only the latter 2 variables were independently predictive. In addition, cDM type (P = .017) was associated significantly and independently with a shorter time to recurrence.
Conclusions: In this largest study to date of patients with DM who underwent SLN biopsy, the SLN-positive rate in patients with DM was lower than that in patients with conventional melanoma. The results indicated that DM type is associated significantly and independently with the time to recurrence and should be evaluated routinely in all patients with PCM. Cancer 2010. (c) 2010 American Cancer Society.