Tailored Treatments: Utilizing Anti-TNFs for Ankylosing Spondylitis and Essential Thrombocytosis

Thrombocytosis is a condition that is often detected incidentally and can be seen both in the course of myeloproliferative diseases (MPD) and as a reactive condition. Ankylosing spondylitis (AS) is a chronic multisystemic inflammatory disease that mainly affects the spine. Mild to moderate thrombocytosis may occur secondary to the course of AS. In the treatment of AS, tumor necrosis factor inhibitor (anti-TNF) treatments are actively used as first-line therapy. The number of cases of MPDs occurring in the course of AS reported in the literature is limited. Although the exact effect of anti-TNF treatment on the MPD process is not fully known, there are publications stating that caution should be exercised in cases of MPD. By this case, we wanted to share our experience of using anti-TNF therapy in a patient diagnosed with ET in the course of AS. The 35-year-old male patient had been diagnosed with AS for 11 years and had been followed up by hematology with the diagnosis of essential thrombocytosis (ET) since 2010. When there was no response to indomethacin and sulfasalazine treatments, the patient was first given etanercept, and after secondary unresponsiveness, infliximab and adalimumab treatments were given. Despite the use of multiple anti-TNFs, no hematological deterioration was detected in terms of ET. Clinical and laboratory responses were also obtained in terms of AS. The patient has been stable and in remission in terms of both AS and ET since 2016.