Our patient was treated with topical steroids and an oral steroid taper for the concomitant lichenoid drug eruption. It is unknown if the steroids affected the course of the KAs or if they spontaneously regressed on their own. Freites-Martinez et al5 described that regression of KAs may be related to an immune response, but corticosteroids are inherently immunosuppressive. They hypothesized that corticosteroids help to temper the heightened immune response of eruptive KAs.5
Our patient had oral ulcers, which may have been indicative of an oral lichenoid drug eruption, as well as skin lesions representative of a cutaneous lichenoid drug eruption. This is a favorable reaction, as lichenoid dermatitis is thought to represent successful PD-1 inhibition and therefore a better response to oncologic therapies.2 Comorbid lichenoid drug eruption lesions and eruptive KAs may be suggestive of increased T-cell activity,2,6,7 though some prior case studies have reported eruptive KAs in isolation.3
Discontinuation of immunotherapy due to development of eruptive KAs presents a challenge in the treatment of underlying malignancies such as melanoma. Immunotherapy was discontinued in 7 of 11 cases due to these cutaneous reactions.3 Similarly, our patient underwent only 1 cycle of immunotherapy before developing eruptive KAs and discontinuing PD-1 inhibitor therapy. If we are better able to treat eruptive KAs, then patients can remain on immunotherapy to treat underlying malignancies. Crow et al8 showed improvement in lesions when 3 patients with eruptive KAs were treated with hydroxychloroquine; the Goeckerman regimen consisting of steroids, UVB phototherapy, and crude coal tar; and Unna boots with zinc oxide and compression stockings. The above may be added to a list of possible treatments to consider for hastening the regression of eruptive KAs.
Our patient’s clinical course was similar to reports on the regressive nature of eruptive KAs within 6 months after initial eruption. Although it is likely that KAs will regress on their own, treatment modalities that speed up recovery are a future source for research.