AB1141 Utility of muscle biopsy with needle in a rheumatology service. a 12 years experience

Background Muscle biopsy with needle is presented as a faster and less invasive alternative than conventional open biopsy for the diagnosis of some myopathies. However, its use as a diagnostic technique is still very limited in the Rheumatology services. Objectives To describe the experience of 12 years and the diagnostic usefulness of needle biopsy in a Rheumatology service. Methods Descriptive study including all patients who, since 2005, had undergone a needle biopsy in the Rheumatology service of the Parc Tauli University Hospital in Sabadell, as a diagnostic technique for suspected myopathy. The technique was performed in all cases on the lateral aspect of the thigh, about 10 cm above the knee. After disinfection and local anaesthesia, an incision of 1 cm longitudinal to the thigh was made until reaching a depth of about 3–4 cm, then introducing the Bergstrom needle for the muscle biopsy (about 4–5 muscle fragments of 2–3 mm taken in different directions) from the vast lateral. Finally, the incision was sutured with a single stitch. In obese patients, a previous ultrasound was performed to exactly knowing the depth at which the muscle sample should be taken. The collected samples were sent fresh to the Pathology service, wrapped in a gauze moistened with 0.9% physiological saline solution. Results In these 12 years we have performed a needle biopsy on 49 patients (29 women). Age 52±10 years (range 25–70). The reason for performing the biopsy was always the increase of muscle enzymes, mainly creatine kinase (CK), which in 9 of the cases was isolated, without any underlying disease, myotoxic drugs or other symptoms. Eight patients presented myalgia or weakness as the only symptomatology. Twelve patients had a rheumatic or autoimmune disease, and in 7 of these 12 cases there was a suspicion of antimalarials myopathy. In 6 cases the suspicion was dermatomyositis and in 5 cases of vasculitis. The biopsy was performed in 4 patients with fibromyalgia and in a patient with diabetes. In 4 of the cases, the suspicion was a lipid-lowering drug myopathy. In 48/49 cases (98%) sufficient muscle sample was obtained. The technique had only to be repeated in one patient due to insufficient or inadequate tissue. Only in 2/49 cases (4%) the histological diagnosis was not concordant with the definitive clinical diagnosis (dermatomyositis), which was confirmed in one patient with open muscle biopsy. In 31 cases (63%) the biopsy was normal. Among the pathological biopsies, the most frequent histological diagnosis was polymyositis, in 12 cases. In 3 cases a dermatomyositis was confirmed, in 3 cases a vacuolar myopathy by antimalarials and in 1 case a necrotizing myopathy. As complications, it should be noted that only 2/49 (4%) patients presented moderate pain, which subsided in less than a week with analgesia, and one patient presented a hematoma in the area. No case of wound infection was observed. Conclusions Muscle biopsy with a needle is a quick, simple, low invasive and safe technique that can be very useful in a Rheumatology department. The incorporation of this technique as a diagnostic tool should be extended to the majority of Rheumatology departments. Disclosure of Interest None declared