A Recent Publication on Acral and Nail Melanomas

The one liner:

This recent publication discusses that tumor depth of 13mm has a poor prognosis (increased risk of lymph node or organ spread).

 

The article discusses a study on the prognostic implications of tumor diameter on acral lentiginous melanoma (ALM). Researchers analyzed data from a database search of 126 patients with non-nail unit acral melanoma and 88 patients with nail apparatus melanoma with available data on tumor size, diagnosed between 1998 and 2020. They determined cutoff values of 13 mm and 230 mm2 for tumor diameter and size, respectively, and found that the prognostic value of tumor diameter was higher than that of lesional size. Long tumor diameter was associated with worse survival in terms of progression-free survival, while survival outcome was not significantly affected by tumor size.

The study further analyzed the relationship between tumor diameter and clinicopathological variables and prognostic data in ALM. In non-nail unit acral melanomas, a tumor diameter longer than the cutoff was associated with a higher percentage of lymph node involvement, higher American Joint Committee on Cancer stage, deeper Breslow thickness, and more frequent ulceration and was more frequently associated with progression and metastasis. In nail apparatus melanomas, deeper Breslow depth, ulceration, and subcutaneous extension were more frequently observed in patients with tumor diameters longer than the cutoff. However, the study’s limitation was that it was a retrospective study performed at a referral center where clinical size could be affected by previous biopsies.

 

Dr. Ezaldein’s take: 

-Tumor depth, measured by the microscope, is going to be more accurate than “guessing” the size of the lesion with the naked eye.

-Dr. Bernie Ackerman (Rest in Peace) famously noted that the depth of a tumor, and its horizontal size are basically represent the same radial growth, just different dimensions (one is on the x-axis, the other on y-axis). It is important to remember this concept when debating the importance of horizontal vs vertical growth.

-This study also had a disproportionate number of lower extremity cases for the acral and nail unit melanomas, which could skew the results. Selection bias is an important characteristic that can affect our interpretations of such studies.

-Nail unit melanomas seem to have a lower threshold for spreading and are usually diagnosed too late, so its important to have a biopsy earlier than later.

 

Link to the study:

https://www.jaad.org/article/S0190-9622(22)01019-2/fulltext