Desmoplastic melanoma: The role of pure and mixed subtype in sentinel lymph node biopsy and survival

Abstract

Background Desmoplastic melanoma (DM) is an uncommon type of melanoma. Two histological subtypes of DM can be distinguished: pure and mixed (PDM and MDM). We hypothesized that discrimination between these subtypes is associated with sentinel lymph node biopsy (SLNB) status and survival. Methods Clinicopathological data from PALGA, the Dutch Pathology Register were retrieved from patients diagnosed with DM in The Netherlands between 2000 and 2014. Clinical and pathological variables were extracted from pathology text files, including pure or mixed desmoplastic morphology. A Cox proportional hazard model was performed for overall and recurrence‐free survival (OS and RFS). Results A total of 239 patients with DM were included, representing 0.4% of all primary cutaneous melanoma in The Netherlands. A total of 114 PDM and 125 MDM patients were identified. MDM was significantly associated with positive SLNB status (P = .035). In multivariable analysis, age (HR 1.10, 95% CI 1.07‐1.14, P < .001) and ulceration (HR 1.98, 95% CI 1.05‐3.75, P = .036) were significant predictors for OS. For RFS, mixed subtype (HR 2.72 95% CI 1.07‐6.89, P = .035), male gender (HR 2.54, 95% CI 1.03‐6.27, P = .043), and Breslow thickness (HR 1.13 per mm, 95% CI 1.05‐1.21, P = .001) were significant predictors. Conclusion MDM is significantly associated with a positive SLNB status. Mixed subtype is significantly correlated with RFS, but not with OS. The distinction between pure and mixed desmoplastic subtype therefore seems to be of clinical importance.

Pure and Mixed Desmoplastic Melanomas: A Retrospective Clinicopathologic Comparison of 33 Cases

“…Mixed DM is associated with positive SLNB status and a higher frequency of regional metastasis. 22,23 Treatment modalities and the recommendations on the use of SLNB have changed over recent years. The National Comprehensive Cancer Network Cutaneous Melanoma Guidelines currently suggests that clinicians may consider forgoing SLNB in patients with confirmed pure DM because of the controversy of its benefit.…”

The utility of SOX10 in mixed type desmoplastic melanoma with lymph node metastasis of the spindle cell component: A cautionary tale of inattentional blindness

“…The distinction between PDM and MDM is also controversial. More studies have found a significantly higher likelihood of nodal metastases in MDM than PDM, 21–24 whereas others have found no difference between their incidence of nodal disease 25 . Consequently and understandably, this has led to diverging opinions with regard to the necessity of sentinel lymph node biopsies for patients with MDM and PDM.…”

Pure and Mixed Variants of Desmoplastic Melanoma: A Single-Center, Retrospective, Clinicopathologic Review

“…The largest of the 3 additional studies included 239 patients and is limited by the study design using only pathology text files to determine subtype. 5 The study methods further state, "If there was no mention of mixed features, it was assumed there was a pure histologic subtype." 5 Also, 2 studies included in both systematic reviews defined pDM as 80% to 90% desmoplasia, which differs from the widely accepted $90% desmoplasia defined by Busam and colleagues 1,15 Two case series of 58 and 33 patients have recently been published showing no difference in SLNB positivity between pDM and mDM.…”

“…4 Because of its subtle clinical presentation, DM can be mistaken for benign neoplasms, including dermatofibroma, scar, or nevus. 5 Diagnosis requires a high index of suspicion followed by appropriate biopsy.…”

“…Desmoplastic melanoma was defined as "mixed" if the tumor contained .10% densely cellular nonfibrotic areas (Figure 2). 5 Reports of prognosis and survival for DM compared with conventional melanoma vary widely. 2,6 The estimated 5-year survival for conventional melanomas regardless of stage is 91%, whereas in DM studies, survival ranges from 67% to 89%.…”