Abstract:

Pembrolizumab, a PD-1 inhibitor, has been associated with multiple cutaneous adverse reactions. Morphea and genital lichen sclerosus (LS) are among the rarer associated reactions. Herein, we present the first reported case of pembrolizumab-associated morphea with features of LS. A 66-year-old female with metastatic renal cell carcinoma, on pembrolizumab for two years and previously on axitinib, presented with a 10-month history of progressively worsening painful rash in her intertriginous areas, previously diagnosed as candidal intertrigo. Skin examination showed pink eroded and ulcerated plaques of varying sizes and shapes in her left axilla, left inframammary fold, bilateral inguinal folds, and gluteal cleft, along with surrounding shiny, hypopigmented, indurated plaques. Punch biopsies showed thickened and homogenized collagen bundles involving the entire reticular dermis, perivascular and periadnexal lymphoplasmacytic infiltrates, and pale, homogenized eosinophilic collagen in the superficial dermis. Histopathology was consistent with morphea with features of LS, which was attributed to pembrolizumab use. The existing literature on pembrolizumab reactions includes only seven cases of morphea and six cases of genital LS, and ours is the first report of 1) pembrolizumab-associated morphea with LS features and 2) pembrolizumab-associated extragenital LS findings. Another interesting aspect of our patient’s case is the diffuse intertriginous distribution of plaques, an unusual and previously unreported presentation of pembrolizumab-associated morphea. As the use of pembrolizumab expands, it is important that clinicians and pathologists alike are aware of the diverse ways in which pembrolizumab-associated morphea/LS may present.

Financial Disclosure:
No current or relevant financial relationships exist.

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Katherine O. Ayoade, MD, PhD