Plaque psoriasis is a chronic inflammatory disease with a complex pathogenesis. Cutaneous dendritic cells drive the activation and proliferation of T cells with production of several immunomodulators, such as tumor necrosis factor (TNF) α, IL-17, IL-12, and IL-23. Because multiple systemic therapies are efficacious, treatment selection depends on side-effect profiles, availability, and patient preference. Activation of the TNF-α pathway is not unique to psoriasis. Tumor necrosis factor α plays a key role in multiple inflammatory conditions, including psoriatic arthritis, rheumatoid arthritis, and hidradenitis suppurativa. One study in mice demonstrated that TNF-α drives endothelial and vascular wall dysfunction in sickle cell anemia. In this study, use of the TNF-α blocker etanercept in mice with homozygous sickle cell anemia (HbSS) disease resulted in amelioration of TNF-mediated clinical features shared by sickle mice and humans.1
Sickle cell anemia is caused by a structural defect in hemoglobin that results in hemolysis and chronic anemia. The most common type of hemoglobin in adults without sickle cell anemia is HbAA. Homozygous sickle cell anemia patients carry 2 abnormal S alleles, whereas in sickle cell trait, patients carry both the S and normal A alleles (HbSA). Hemoglobin C is a structural variant of HbA that results in lower solubility in red blood cells. Patients with hemoglobin SC disease (HbSC) have S and C alleles.2 We present a case of a patient with moderate to severe plaque psoriasis and heterozygous sickle cell anemia treated with adalimumab.
A 31-year-old woman presented with moderate to severe plaque psoriasis (70% body surface area) and HbSC. She reported chronic dull arthralgia in the ankles that was worse at night. Radiographs of the feet and ankles showed erosive changes of the distal tarsal row and metatarsal bases. The diffuse bone pain had gradually worsened over the years and was treated by hematology with ibuprofen and ketorolac. At presentation, her HbSC pain was 8/10 on a visual analog scale. She described her sickle cell pain crises as sharp 10/10 pain in the back, elbows, and ankles, associated with mild edema lasting 1 to 2 days. Radiographs of the spine, hands, and ankles were unremarkable.
Adalimumab was chosen as a systemic therapy for psoriasis based on the potential for improvement in HbSC. Within 17 weeks of starting adalimumab, the psoriasis body surface area decreased from 70% to 40%, and the HbSC pain decreased from 8/10 to 4/10 at 8-week follow-up and to 0/10 at 17-week follow-up. After initiation of adalimumab, she reported decreased use of pain medication with no sickle cell pain crises.