Clinical Pathologic Mismatch in a TNF-α Inhibitor-Associated Drug Reaction

A 56-year-old Caucasian male with a history of chronic plaque psoriasis, primary sclerosing cholangitis status-post liver transplant on tacrolimus, and ulcerative colitis on infliximab developed a progressive erythematous eruption with associated fatigue, anorexia, myalgias, and arthralgias. On two separate occasions, his skin biopsy demonstrated a lichenoid interface dermatitis (LID). Despite multiple courses of oral prednisone, topical steroids, and a short course of hydroxychloroquine, his symptoms continued to relapse and remit. When a temporal association between increasing his infliximab dose and the global progression of his disease was identified, he was ultimately diagnosed with a TNF-α inhibitor-induced psoriasis flare. Despite the patient’s long-standing history of psoriasis, a plausible psoriasis rebound reaction after systemic steroids was not strongly considered in light of his histopathology. Though lichenoid interface dermatitis is a commonly reported histologic finding in patients on TNF-α inhibitors, it has scarcely been reported in patients with psoriasiform eruptions clinically.