Melanoma : Metastasis - Lymph Node
Melanomas spread laterally along the dermoepidermal junction (radial growth phase) as well as invade dermis and subcutaneous tissues (vertical growth phase). Metastases to regional lymph nodes occur quite commonly.
Distant metastases can occur to virtually any organ and even within other tumors. The most common sites for distant metastases are liver, lungs, gastrointestinal tract, brain, and bones.
Cutaneous metastases can occur in the form of satellite nodules (microscopic tumor foci located near the main tumor) or in-transit metastases (cutaneous and subcutaneous tumor nodules located between the primary tumor and the regional lymph nodes). Both indicate disseminated disease. Cutaneous metastases may have secondary intraepidermal component making it difficult to distinguish them from primary tumor. In such cases, if the dermal component is wider than the epidermal one, it supports cutaneous metastases.
The image shows metastatic melanoma (amelanotic) in a lymph node. Image copyright: pathorama.ch.