You can consider SLNB for lesions 0.75–1.0 mm if tumor has other high-risk features like ulceration and mitotic rate >1/mm2.

Thank you for your answer. So, regression should be just ignored. Even in those cases when the pathologist describes a very thick regression!?

According to literature, among other potential predictors of SLN positivity, the significance of tumor regression is controversial. Recent studies have reported no association between the presence of regression and the incidence of SLN positivity.

1. Fontaine D, Parkhill W, Greer W, Walsh N. Partial regression of primary cutaneous melanoma: is there an association with sub-clinical sentinel lymph node metastasis? Am J Dermatopatol 2003; 25:371-376

2. Morris KT, Busam KJ, Bero S, i sur. Primary cutaneous melanoma with regression does not require a lower treshold for sentinel lymph node biopsy. Ann Surg Oncol 2008;15:316-322

Thank you once again. Maybe the fear of regression has its origins in those melanoma cases with complete regression associated with metastatic spread. I glanced at the histopathologic examinations of some of my melanoma patients that died or had bad forms of locoregional recurrent melanoma (even ending with amputation of the whole limb). Regression was mostly present. But there were also other more reliable prognostic sings (thickness, ulceration, mytotic rate). Perhaps regression is not an uniform process?

Only if there are special circumstances, such as other high risk factors

I agree with Dr Horvatić-Herceg in not to recommend the performance of SLNB based only in the presence of regression for thin melanomas. Additional literature can be found here in Research Gate...https://www.researchgate.net/publication/262885528_Correlation_of_Histologic_Regression_in_Primary_Melanoma_With_Sentinel_Node_Status

Article Correlation of Histologic Regression in Primary Melanoma Wit...

This action is not recommended bz melanoma with thickness less than 1 mm of Breslow index. It should be recommended further follow regrresion melanoma and ultrasonography follow of regional lymphnodes.

The best prognostic factor and indication for SNLB is thickness of melanoma or Breslow index. Probabilty for involvement of lymphe nodes by Breslow index less than 1 mm is also very low, but should be verry carrefully.

 As said regression is a variable process. Focal regression is almost constant in LM and ALM. Complete regression is more frequent with SSM. Most of the time regression occurs on the side of the melanoma and does not change the estimation of histoprognostic factors. In my reports I detail if I believe that regression, when present, is at risk of underestimation of Breslow etc. Some pathologist evaluate a % of lesional surface that has regressed. Ask your pathologist for more details on the extent of the regression and mostly if it occurs on the side or underneath your thickest invasive area. 

Thank you for the answer. So, regression shoul be considered in some cases even in melanoma depth less than 1 mm.

Hi Marko, I think that SLNB should be performed in almost all cases of melanoma. Melanoma is a cancer with a strange molecular behavior given that in some cases apparently benign lesions diagnose with melanoma and that some patients with extirpate grade I melanoma develop metastasis also after 5 years follow-up. Moreover, there is a form of melanoma called "Sub-clinical Melanoma" which affected patients die with multiple metastasis but without clinical skin lesion.

This is the reason why I think that performing SLNB in all cases is the most scrupulous choice.

Kind Regards,

FM

I agree, melanoma can make unpredictable surprises and the approach to every patient with a melanoma should be distinctive! I am especially perplexed in those cases of melanoma thinner than 1 mm with a wide histologic regression. For years pathologists have warned me of regression as a bad prognostic sign, but it seems that it could be even considered as a "good" sign!?

Association of Histologic Regression in Primary Melanoma With Sentinel Lymph Node Status. A Systematic Review and Meta-analysis

Simone Ribero, MD, PhD1,2; Maria Rosaria Gualano, MD3; Simona Osella-Abate, ScD1,4; Giacomo Scaioli, MD3; Fabrizio Bert, MD3; Martina Sanlorenzo, MD1; Elena Balagna, MD2; Maria Teresa Fierro, MD1; Giuseppe Macripò, MD2; Anna Sapino, MD4; Roberta Siliquini, MD3; Pietro Quaglino, MD1

JAMA Dermatol. 2015;151(12):1301-1307. doi:10.1001/jamadermatol.2015.2235.

Best regards!

Regression would be a good sign; why did pathologists tell you that it is a bad sign? For all the things i've previously said, i feel confident in saying that performing of SLNB in all melanoma cases is the most scrupulous choice.

Best regards!