case_images: PMC11116557_01
case_images: (A) The patient's frontal scalp demonstrated erythematous nodules, consistent with in-transit metastases of cutaneous squamous cell carcinoma, before combination treatment with pembrolizumab and diphencyprone (DPCP). DPCP was applied to the boxed area. The asterisk denotes the area of sensitization. (B) Regression of the in-transit metastases after a 12-week course of combination treatment with pembrolizumab and DPCP.
case_images: fonc-14-1294331-g001.jpg
case_images: PMC11116557_01_fonc-14-1294331-g001.jpg
case_images: f1
case_images: Two months after the primary tumor resection, the patient presented with multiple, firm, erythematous nodules on his scalp ( Figure 1A ). At the end of the 12-week treatment period, the patient had resolution of all metastases, including the DPCP-treated and non-DPCP-treated lesions ( Figure 1B ).
case_images: Hematoxylin and eosin (H&E) stains of cutaneous biopsies. (A) Baseline non-lesional skin demonstrates benign skin tissue, negative for tumor (20X magnification). (B) Baseline in-transit metastasis demonstrates moderately to poorly differentiated infiltrative cutaneous squamous cell carcinoma (cSCC) with focal keratinization completely within the dermis. There is mild inflammatory infiltrate associated with tumor proliferation (20X). (C) In-transit metastasis two weeks post-treatment with pembrolizumab only (diphencyprone (DPCP) not applied) demonstrates diffuse dermal infiltration of moderately to poorly differentiated cSCC with focal keratinization (20X). (D) In-transit metastasis two weeks post-treatment with DPCP and pembrolizumab demonstrates lichenoid dermatitis with diffuse dermal inflammatory and fibrotic changes. No cSCC is identified (40X). (E) In-transit metastasis after 12 weeks of treatment with pembrolizumab only demonstrates benign skin tissue with minimal changes including mild dermal fibrosis and perivascular inflammatory infiltrate (20X). (F) In-transit metastasis after 12 weeks of treatment with DPCP and pembrolizumab demonstrates spongiosis, superficial dermal edema, patchy inflammatory infiltrate, and dermal fibrosis. No cSCC is identified (40X).
case_images: fonc-14-1294331-g002.jpg
case_images: PMC11116557_01_fonc-14-1294331-g002.jpg
case_images: f2
case_images: Given the positive clinical response, additional cutaneous biopsies were performed of a DPCP-treated metastasis and a non-DPCP-treated metastasis ( Figures 2C, D ). At this time, follow-up biopsies of a prior DPCP-treated metastasis and a non-DPCP-treated metastasis were taken ( Figures 2E, F ).