Tumoral melanosis mimicking residual melanoma in the setting of talimogene laherparepvec treatment

J Immunother Cancer. 2022 Oct;10(10):e005257. doi: 10.1136/jitc-2022-005257.


Talimogene laherparepvec (T-VEC) has become an increasingly popular treatment option for surgically non-resectable, recurrent melanoma, usually of cutaneous metastases. The complete response (CR) rate has been reported to be ~20% with a median of ~9 months to achieve it. In real-world practice, decrease of tumor size often occurs rapidly within the first 2-3 months, while improvement of the pigmentation takes several more months. Such clinical observation of lasting pigmentation could be explained by tumorous melanosis-a histopathological term referring to the presence of a melanophage-rich inflammatory infiltrate without remaining viable tumor cells. Herein, we report six patients with metastatic cutaneous melanoma who were treated with T-VEC. Biopsies were performed after observing clinical responses in the injected tumors. Pathological evaluation demonstrated non-viable or absent tumor tissue with tumorous melanosis in all cases. To accurately assess response to therapy and potentially decrease unnecessary additional T-VEC treatments, serial biopsy of 'stable' lesions should be considered to assess the presence or absence of viable tumor.

Keywords: Case Reports; Immunotherapy; Melanoma; Oncolytic Viruses.

MeSH terms

  • Disease Progression
  • Humans
  • Melanoma* / diagnosis
  • Melanoma* / drug therapy
  • Melanosis* / diagnosis
  • Melanosis* / therapy
  • Neoplasm Recurrence, Local / therapy
  • Oncolytic Virotherapy*
  • Skin Neoplasms* / diagnosis
  • Skin Neoplasms* / drug therapy


  • talimogene laherparepvec

Supplementary concepts

  • Melanoma, Cutaneous Malignant