Tumor necrosis factor (TNF)-alpha inhibitors are used to treat a variety of autoimmune conditions including psoriasis, psoriatic arthritis, rheumatoid arthritis (RA), spondyloarthritis, and inflammatory bowel disease (IBD). Interestingly, they have also been observed to cause paradoxical psoriasis with an incidence between 0.6%-5.3%, most commonly occurring in patients with underlying Crohns disease and rheumatoid arthritis (RA). Infliximab is the most common TNF inhibitor associated with this condition (52.6%-62.6% of cases) followed by etanercept (12%-29%). TNF inhibitor-induced psoriasis most often presents as plaque or palmoplantar psoriasis, but other subtypes have also been documented.

Psoriasis is traditionally divided into two types. Patients with type I psoriasis have a family history, develop symptoms before the age of 40 and are often positive for HLA-Cw6. Type II psoriasis is not related to HLA-Cw6, lacks a family history, and typically manifests after age 40. Psoriatic lesions are well-defined, erythematous plaques with silvery scales most commonly appearing on extensor surfaces and the scalp. Variants include nail psoriasis, pustular psoriasis, inverse psoriasis, and guttate psoriasis.

Although psoriasis is typically a clinical diagnosis, histologic examination may be used to differentiate from other dermatoses if necessary. The lesions of TNF inhibitor-induced psoriasis characteristically display patterns similar to primary psoriasis, including parakeratosis, microabscesses, and rete ridges. Eosinophilic hypersensitivity reactions and features overlapping with eczematous hypersensitivity (psoriasiform dermatitis) may also be present.

The pathogenesis of this condition is not well understood, but theories include a variety of immune processes including interferon overproduction, interleukin and T-cell activation, and the presence of an infectious nidus. Classical psoriasis is related to type 1 interferon release, so theoretically, immunosuppression caused by TNF inhibitor treatment may permit uncontrolled production of interferons, resulting in psoriatic lesions. Another theory is that interleukin (IL)-23, a pro-inflammatory cytokine, promotes activation of T-helper 17 (Th17) cells. Th17 cells are part of the pathogenesis of primary psoriasis and other inflammatory conditions, such as RA and inflammatory bowel disease. Of note, individuals with gastrointestinal inflammatory diseases are already known to be at a greater risk for developing psoriasis. Immunosuppression caused by a TNF inhibitor may leave patients more susceptible to other infections, which may induce psoriatic plaques.

There are multiple approaches to treatment depending on the severity of the disease. If the psoriatic eruption is mild, the medication may be continued. This treat-through method is often considered when stopping the current immunotherapy would cause the patient significant issues. Moderate to severe cases of TNF inhibitor-induced psoriasis may warrant switching TNF inhibitor therapy or completely changing the drug class used in the treatment of the underlying autoimmune condition. Additional treatments include topical and oral steroids, UV therapy, methotrexate, cyclosporine, and acitretin.

This case and the photo were submitted by Lucas Shapiro, BS, of Nova Southeastern University College of Osteopathic Medicine, Fort Lauderdale, Florida, and Leon S. Maratchi, MD, Gastro Health, Hollywood, Florida. The column was edited by Donna Bilu Martin, MD.

Dr. Bilu Martin is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Florida. More diagnostic cases are available at mdedge.com/dermatology. To submit a case for possible publication, send an email to dermnews@mdedge.com.

1. Li SJ et al. J Psoriasis Psoriatic Arthritis. 2019 Apr;4(2):70-80. doi: 10.1177/2475530318810851.

2. Lu J and Lu Y. J Transl Autoimmun. 2023 Sep 6:7:100211. doi: 10.1016/j.jtauto.2023.100211.

3. Nair PA and Badri T. Psoriasis. [Updated 2023 Apr 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: http://www.ncbi.nlm.nih.gov/books/NBK448194/

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A 30-Year-Old White Female Presented With a 4-Month History of Scaly, Erythematous Patches and Plaques on Her ... - MDedge