Abstract

Background: Lymph nodes, known to filter foreign substances like tumor cells and infection, can occasionally contain extrinsic material (tattoo pigment) or heterotopic tissue (nodal nevi). Herein, we present an unusual finding of solar elastotic material in the dermal lymphatics and sentinel lymph node (SLN) in a patient with melanoma. Case description: An 80-year-old man presented with a multicolored papule on the right elbow, which demonstrated invasive melanoma on shave biopsy with no lymphovascular invasion. Wide local excision with SLN biopsy was carried out. The resection specimen did not show residual melanoma, and all three SLNs were negative for metastatic melanoma. Interestingly, in one of the SLNs, the capsular and trabecular lymphatics contained solar elastotic material. Similar solar elastotic material was identified within the dermal lymphatics of the excision specimen. Verhoeff-Van Gieson and elastin immunostaining highlighted the solar elastotic material, while D2-40 immunostaining confirmed its presence within the lymphatics. Conclusion: To our knowledge, solar elastotic material in lymph nodes has only been reported in one series of 9 patients; 8 with melanoma and one with Merkel cell carcinoma (Pullitzer MP et al.). The material was noted in benign, unremarkable nodes, as well as nodes with metastatic disease or nodal nevi. Trauma, potentially from biopsy, is a hypothesized mechanism for this phenomenon. Mechanical transport via lymphatics explains the transfer of both benign and malignant tissue to the lymph node.

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