Track: Case Reports

Topic: Melanocytic Neoplasms

Abstract:

Tumor seeding is a devastating complication that can occur following procedural treatment for tumor or tumor metastasis. In this case report, we report a case of tumor seeding in a 70 y.o. male with a history of stage IV M1a uveal melanoma with metastases to the lung, muscle and soft tissue. He was treated with systemic therapy including selumetinib and pembrolizumab. The patient presented with a blue spot on his right thigh shortly after a cryoablation procedure performed at the same site for soft tissue metastasis. Punch biopsy of the skin of the right thigh showed melanosis, chronic inflammatory infiltrate, and focal fibrosis involving dermis consistent with completely regressed melanocytic lesion. No viable melanoma cells were identified on SOX10 immunostaining. A subsequent excision of the soft tissue of the right thigh showed similar histologic findings consistent with completely regressed melanoma, suggesting that the findings from the patient’s punch biopsy represented tumor seeding from the patient’s metastatic thigh lesion. To the best of our knowledge, this case represents the first known case of tumor seeding resulting from cryoablation of completely regressed metastatic uveal melanoma. Herein, we report it to raise awareness of this uncommon occurrence by pathologists, dermatologists and oncologists to avoid possible misdiagnosis and ensure appropriate management.

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Eric Zhang, MD