Pseudoprogression of a Head and Neck Cutaneous Squamous Cell Carcinoma Treated with Anti-PD-1 Immunotherapy: A Case Report and Review of the Literature.

INTRODUCTION

Pseudoprogression during immunotherapy (IO) - defined as clinical documentation of tumor growth or new lesions during treatment with immune checkpoint inhibitors, followed by disease regression - has been reported in ≤10% of cases. Its incidence appears to be lower in cutaneous squamous cell carcinoma (cSCC) patients (1.5-4%).

CASE PRESENTATION: We report a rare case of pseudoprogression of an advanced cSCC during IO (cemiplimab). Following initial surgery for a cSCC of the left auricular area, the tumor recurred and infiltrated the ear cartilage and external auditory meatus. At the time of administration of the second IO, the tumor had rapidly grown with a fulminant pattern and doubled in size. Treatment with IO continued, as per protocol, and by the third infusion appointment, the tumor had disappeared, and complete re-epithelialization of the auricular area was observed, confirming pseudoprogression. So far, the patient has received ten cycles of IO without experiencing toxicity, and there has been no sign of disease recurrence.

CONCLUSION

Awareness of potential pseudoprogression is crucial for clinicians managing advanced cSCC with cemiplimab.