Whole-body muscle magnetic resonance imaging in patients with muscle symptoms: incidental findings and outcomes.

BACKGROUND AND PURPOSE: Whole-body muscle magnetic resonance imaging (MRI) has become widely used for diagnostic workup in patients with muscle diseases. The prevalence of incidental findings in diagnostic whole-body muscle MRI is unknown. Here, the prevalence and outcomes of incidentalomas in whole-body muscle MRI in a large cohort of patients with muscle symptoms were studied. METHODS: Two hundred and six patients who consulted at our neuromuscular clinic with muscle weakness and/or myalgia and/or increased serum creatine kinase and in whom a whole-body muscle MRI was performed between January 2016 and March 2020 were included. RESULTS: Whole-body muscle MRI revealed at least one incidentaloma in 132 patients (64.1%), with mean age at MRI examination 50.4 years (19-74 years). Most of the incidental findings were benign. However, diagnostic examinations were indicated in 16.3% of the incidentalomas, treatment was needed in 4.7% and, in retrospect, symptoms related to the incidental findings were identified in 14.3%. Three malignant (glioblastoma multiforme, renal cell carcinoma and hepato-splenomegaly related to a lymphoma) and one precancerous (low-grade appendiceal mucinous neoplasm) incidental findings were identified. In one patient an abdominal aortic aneurysm was detected and in another a large cerebral arteriovenous malformation. In 1.2% of the incidentalomas, i.e. periventricular white matter lesions (LAMA2 mutations) and fibrous dysplasia (ANO5 mutations), an indirect link with the muscle disease could be established. CONCLUSIONS: It is concluded that incidental findings in diagnostic whole-body muscle MRI in patients with muscle symptoms occur frequently. Most of them are benign, but in some timely detecting the incidentaloma leads to early treatment and can thus impact prognosis.

Longitudinal cortical split sign as a potential diagnostic feature for cortical osteitis.

Septic cortical osteitis is a rare but distinct type of bone infection that is characterized as a hematogenously seeded infection predominantly or exclusively limited to the cortex. Diagnosis is difficult and often delayed. Combination of clinical and laboratory findings together with the typical radiological findings consisting of vertically orientated cortical osteolysis, the 'cortical split sign' and the predominantly cortical disruption at the periosteal side of the cortex may lead to the correct diagnosis.

Radiation-induced mandibular adult spindle cell rhabdomyosarcoma.

Spindle cell rhabdomyosarcoma (RMS), a variant of embryonal RMS, is a rare tumour, especially in adults. Imaging techniques are used to evaluate the extent of the tumour whereas a biopsy is required to make the final diagnosis. In this article we describe a case of mandibular Spindle cell RMS in a previously irradiated field in a 56-year-old male, and discuss the clinicopathologic and imaging findings. Although the aetiology is still unclear, this case suggests that previous radiation therapy can be a causal factor.