Background Systemic lupus erythematosus (SLE) is a chronic inflammatory disease of unknown etiology that may affect the skin, joints, kidneys, lungs, nervous system, serous membranes, and/or other organs of the body. Ankylosing spondylitis (AS) is a chronic inflammatory disease of the axial skeleton manifested by inflammatory back pain and progressive stiffness of the spine. These two autoimmune rheumatologic diseases, which have different etiopathogenesis, as well as diverse clinical and genetic characteristics, are seldom seen together.

Objectives Hereby, we present a 55-year-old female patient, being followed up with the diagnosis of SLE with locomotor, skin, renal and hematopoetic system involvement for eight years, who also suffered from inflammatory low back pain approximately for the last four months.

Results Sacroiliac magnetic resonance imaging (MRI) confirmed the presence of bilateral sacroiliitis and HLA-B27 was positive. So, additional diagnosis of AS was made eight years after the diagnosis of SLE. Her laboratory test results were as follows: white blood cell count 3.85/μl (4.60-10.2), hemoglobin10.4g/dL (12.2-18.1), antinuclear antibody test 1/320 granular, anti-double-stranded DNA positive, Complement 3 65 mg/dl (83-193), Complement 4: 3 mg/dl (15-57). Renal biopsy was performed, and histopathological examination showed membranous glomerulonephritis, consistent with class V lupus nephritis. Inflammatory low back pain responded to treatment with non-steroidal anti-inflammatory drugs.

Conclusions Including the present case, most of the reported cases of SLE and AS coexistance are females and generally SLE precedes the occurence of AS[1]. The present case is also notable with having MRI confirmation of bilateral active sacroiliitis with bone marrow edema. The coexistance of these two diseases with different genetic bacgrounds and clinical symptoms may implicate the importance of shared enviromental factors.

1. Mrabet D, Rekik S, Sahli H, Trojet S, Cheour I, Eleuch M et al (2011) Ankylosing spondylitis in female systemic lupus erythematosus: a rare combination. Lupus 20(14):777-8

Disclosure of Interest None Declared