Although early studies showed preexistent nevus associated with ALM to be rare, recent publications tend to underline the presence of
nevus cells in some cases, and a case control study of ALM, done in Australia and Scotland, found patients with ALM did have higher total body and acral nevi counts.
Thus, when examining an SLN, it may be very important to study the original melanoma and to compare the morphologic features, particularly to distinguish metastatic cells from macrophages or
nevus cells (see also below the section on differential diagnosis).
Nevus cell aggregates associated with lymph nodes: estimated frequency and clinical significance.
One such structure is the
nevus cell aggregate, which occurs in up to 6.
Furthermore, another common patient-mentioned provoking factor for HN was physical trauma (including scratching and friction), which could injure the
nevus cells and cause the release of some covert autoantigens by nevomelanocytes and the subsequent inflammatory infiltration.