Bilateral acute sacroiliitis due to isotretinoin therapy: a case report

Abstract

We report here a case of a young female patient who developed sacroiliitis related to isotretinoin (13-cis-retinoic acid) use which completely resolved following discontinuation of the medication. Isotretinoin, a retinoid indicated for the treatment of severe cystic acne, has been associated with adverse effects, including musculoskeletal symptoms such as arthritis, arthralgia, myalgia and soft tissue calcification. Reactive sacroiliitis is a rare side effect. A small number of cases of sacroiliitis occurring in association with isotretinoin use have been described.1-3 A 20-year-old healthy woman was admitted to our department with complaints of myalgia, bilateral hip, pelvic and low back pain. She was not using any drugs except isotretinoin, which she had been using to treat acne for the previous 3 months (initial dose 30 mg/day for the first month, then increased to 40 mg/day for the following 2 months). Because of increased pain, the patient had stopped using the drug 15 days ago. On physical examination, sacroiliac joints were very painful and Gaenslen, Thigh Thrust, Patrick Faber and Mennel tests were strongly positive. Muscle power was normal (Medical Research Council scale 5/5). Laboratory examination showed that the erythrocyte sedimentation rate was 52 mm/h (normal range 0–20), C-reactive protein 2.75 mg/dL (0.0–0.5), creatine-kinase (CK) 43 U/L (30–200). Antinuclear antibodies, antineutrophil cytoplasmic antibodies, rheumatoid factor, C3, C4 were all negative. Blood chemistry, thyroid function tests and complete blood count were unremarkable. Screening for viruses and brucella was negative. Human leukocyte antigen (HLA)-B27 was positive. X-ray of pelvis and sacroiliac joint was normal. Magnetic resonance imaging (MRI) showed bilateral active inflammatory sacroiliitis with evidence of bone marrow edema adjacent to both sacroiliac joints. In dynamic contrast enhanced MRI, Fehn activity was measured 103% around the right sacroiliac joint and 75% around the left sacroiliac joint. These measures were compatible with prominent activity (Fig. 1). The patient was treated with prednisolone (15 mg daily slowly decreasing until suspension) and diclofenac sodium (75 mg daily) with gradual improvement over 2 months. After 6 weeks, the symptoms had completely resolved and the laboratory results had improved, so the treatment was stopped. There was no complaint and the laboratory results were normal on the sixth month of follow-up. The use of the Naranjo probability scale indicated a probable relationship between isotretinoin therapy and sacroiliitis.4 Isotretinoin is a retinoid that is used to treat cystic acne, comedonal acne and other diseases. Its most common side effects are mucocutaneous and ocular in nature (i.e., cheilitis, ocular sicca and decreased dark adaptation).5 Reactive sacroiliitis is a rare side effect. On physical examination and MRI findings, we see the symptoms related to sacroiliitis which are mentioned above in our patient. After isotretinoin treatment was stopped, the complaints in our patient vanished. Bilateral symmetrical sacroiliitis can be seen in seronegative spondyloarthropathies, although the presentation in this case is not characteristic of any of these disorders. The patient had no infectious conditions capable of initiating reactive arthritis and lacked both a history and symptoms of inflammatory bowel disease, psoriasis, uveitis, conjunctivitis or peripheral arthritis inconsistent with ankylosing spondylitis, enteropathic arthropathies or psoriatic arthropathy.6 The mechanisms underlying the induction of sacroiliitis by isotretinoin are not currently known. HLA-B27 was positive in our patient. It may be possible that patients with HLA-B27 could be more prone to developing sacroiliitis with isotretinoin use or sacroiliitis might have been triggered by isotretinoin.3 During isotretinoin treatment, patients may become colonized with Staphylococcus bacteria. Thus, it is reported in the literature that the frequency of incidence of perioral abscess formation, severe mucositis or angioedema, increase in patients having isotretinoin treatment.7 Cell-mediated autoimmunity which may develop with hypersensitivity reaction related to isotretinoin treatment may be responsible for multiple target involvement.5 We report here that isotretinoin treatment is usually used in acne treatment, may cause sacroiliitis development or trigger it in healthy people. We advise rheumatologists to be aware of this side effect. None.