Inflammatory Discitis (Andersson Lesions) in a Seronegative Arthropathy Other Than Ankylosing Spondylitis

We report the case of a 48-year-old male patient who initially presented with a peripheral arthropathy and a rash that progressed to debilitating axial symptomatology responding positively to anti-TNF therapy. The patient presented with bilateral knee and ankle pain and a rash that eventually involved the trunk, arms, and legs. When he developed thoracic spine pain, imaging of the thoracic spine was performed, showing disk erosions and a paravertebral inflammatory mass. Subsequent tests included skin biopsy with a diagnosis of psoriasis and presumed associated lower extremity arthropathy. However, he was also found to have a latent TB infection. Especially with the possibility that the axial manifestations were related to the infectious diagnosis, the patient was started on isoniazid. However, there was clinical progression of the lower extremity symptoms while he was on isoniazid. Therefore, he was subsequently started on a TNF-inhibitor, etanercept (Enbrel), for psoriatic arthritis, with marked improvement in both axial and peripheral symptoms and no progression of the paravertebral mass. The spinal lesions were thus interpreted as AL, an inflammatory diskitis usually associated with AS. To our knowledge, AL have never been reported in association with psoriatic arthritis; thus, it is a unique manifestation.