The patient was admitted as an emergency at Accident and Emergency department with high fever, respiratory insufficiency, generalised muscle pain and weakness. She had had an abortion 2 months before and suffered from sickle cell anaemia. After chest radiography and the initial blood examination, she was admitted to our radiology department for further work-up.
The patient initially underwent plain chest radiography, which was normal. Due to her pain and the tenderness, mostly at the left iliac bone, she was further evaluated with a pelvic MRI. The major question was whether the patient's symptoms were due to osteomyelitis or an acute infarction. On coronal T1W images (Fig. 1 a, b), the bone marrow had the characteristic low MR signal of sickle cell anaemia changes. On STIR images demonstrated massive bone oedema, more prominent at the left iliac bone and femora (Fig. 2 a, b). A small fluid collection was seen at the left illiopsoas muscle (Fig. 2 c). Following bone and soft tissue biopsies were negative. After intravenous therapy the patient was symptom-free and discharged home. Decrease of bone oedema was present on the STIR sequences (Fig 3 a, b) at the follow-up MRI approximately two months after the initial evaluation.
Sickle cell disease (SCD) is a congenital haemoglobinopathy in which erythrocytes are dense, having a particular non-deformable shape. It may have different manifestations in numerous organs such as spleen, bones, eyes and central nervous system [1]. Vaso-occlusion crisis (VOC) is one of the most frequent complications in a SCD patient. The respective complication occurs due to microcirculation obstruction, which leads to local ischaemia and acute infarctions. Acute bone crises in SCD are precipitated by unknown mechanisms, although trauma, systemic infection, fever, stress, and other causes result in a really severe appearance of intense pain, tenderness, fever and local redness, same as in acute osteomyelitis (AO). These two pathologic entities have to be treated in a different way, although in most of the cases patients take large amounts of antibiotics. Radiographs are not helpful in acute bone marrow infarction (ABI), as they are usually normal during the initial phase of a VOC [1]. Additional radioisotope bone scan using a combination of radioisotopes can reliably detect areas but the specificity is low [2]. Ultrasound is mainly used as an interventional tool for ultrasound-guided biopsy. MRI is the gold standard imaging modality used, because it can detect the pathology of the bone marrow, soft tissues and intra-articular space, helping in the differential diagnosis and follow-up after treatment. Herein there is a large overlap between imaging findings of an ABI and AO, and therefore their differentiation might be quite a dilemma. Features that favour the diagnosis of osteomyelitis include involvement of the soft tissues and abscess formation. Also after intravenous contrast medium osteomyelitis may show a more geographic and irregular marrow enhancement, while acute infarcts demonstrates often a thin, linear rim enhancement. Although, contrast medium imaging can differentiate acute osteomyelitis from bone infarction, new studies demonstrate a potential role of MRI without contrast with equivalent diagnostic value [3]. Most patients recover from vaso-occlusive crises with no functional complications. Patients suffer chronic infarctions since early childhood [4]. However, when the infarction involves the epiphyses, it may give rise to joint effusions that are clinically similar to septic arthritis. Long-standing complications of infarctions at the epiphysis include short stature and kyphosis due to vertebral collapse. Avascular necrosis leads to faster and more severe disability, because infarctions in SCD are larger compared to other causes. In addition, hyperplasia of the bone marrow may cause osteopenia and growth disturbance [1, 4, 5]. Vaso-occlusive crisis could be due to acute infarction or osteomyelitis.
Acute bone infarcts
Based on the provided MRI images of the pelvis and hip joints, there are signal abnormalities in the bilateral proximal femurs (mainly involving the femoral heads and necks). On T1-weighted sequences, localized low or iso-signal intensity is observed, whereas T2-weighted sequences show areas of high or mixed signal intensity, with some lesions having linear or thin ring-like enhancement at the edges. No obvious extensive soft tissue swelling or abscess formation is evident, and no large effusion is seen in the joint space. Some images show scattered or patchy abnormal signals in the femoral heads, suggesting changes in the bone marrow structure. However, soft tissue involvement appears relatively limited, and there is no indication of widespread soft tissue destruction or notable abscess signals.
Combining the patient’s history of sickle cell disease, clinical symptoms (fever and bone pain), and MRI findings, the most likely diagnosis is acute bone infarction (bone marrow infarction caused by a vaso-occlusive crisis). Although osteomyelitis remains a differential diagnosis, the present imaging characteristics more strongly suggest ischemic damage secondary to a vaso-occlusive crisis.
Treatment Strategy:
Rehabilitation and Exercise Prescription:
This report is based solely on the provided medical history and imaging data and is intended to serve as a reference for clinical diagnosis and treatment. It cannot replace in-person medical consultations or the definitive opinion of a qualified physician. Final diagnostic and treatment decisions should be made according to the patient’s actual condition and under the guidance of an appropriate specialist.
Acute bone infarcts
