Introduction:Psoriatic Arthritis (PsA) is an immune-mediated disease. The effectiveness of biologics has changed therapeutic strategies for psoriasis. We report a case of leukopenia in a patient with psoriatic arthritis (PsA) who was treated with Ustekinumab.

Case presentation: A 36- year- old Syrian female presented for a follow up concerning treatment of psoriatic arthritis. She was diagnosed with psoriatic arthritis according to the CASPAR criteria.

She was treated with Methotrexate, then Sulfasalazine. On presentation, the physical examination revealed tender in metacarpals, proximal interphalengal joints and distal interphalengal joints of both hands.

Laboratory analysis showed: white blood cells (WBC) :3500 /mm³, (Neut:23% n = 40-65%, Lymp:65% n= 25-40%), erythrocyte sedimentation rate (ESR): 40 mm/h1, and C-reactive protein (CRP): 9.3 mg/L . Given the patient’s ongoing disease activity, and the presence of leukopenia, we started with Ustekinumab 45 mg subcutaneous. After the third dose of Ustekinumab, evaluation showed improvement in her peripheral arthritis and normal laboratory findings.

Discussion: Patients with psoriasis had higher total white blood cell and neutrophil. Ustekinumab has good efficacy against disease activity as well as a favourable safety profile. In literature, we found a case of myelodysplastic syndrome associated with inflammatory bowel disease treated with Ustekinumab. Another case of constitutional neutropenia and psoriasis vulgaris treated with Ustekinumab.

Conclusion: This is the first case of leukopenia associated with PsA successfully treated with Ustekinumab.

UST treatment might be recommended for leukopenia associated with PsA, but further researches are recommended.

TASNEEM DRIE