Teaching Point: Dynamic ultrasound and knowledge of a clinical history of a soft-tissue lump that increases in volume upon muscle contraction or weight-bearing are crucial in the diagnosis of muscle herniation

Dierickx, Jesper

Vanhoenacker, Filip

English

Ghent University Academic Bibliography

Case PresentationA 42-year-old woman was referred for magnetic resonance imaging (MRI) for evaluation of a painless soft-tissue swelling on the lateral side of the lower leg. The lesion had been present for many years and was more prominent in standing position. There was no history of trauma. A skin marker was placed at the soft-tissue lump in standing position. MRI showed subtle bulging of the contour of the peroneus longus muscle belly (Figure 1A, white arrow). The lesion was iso-intense to muscle tissue on all pulse sequences. There was no volume increase upon peroneus longus muscle contraction in supine position (Figure 1B). Subsequent dynamic ultrasound in standing position con-firmed protrusion of peroneus longus muscle tissue (white arrow) through a fascial defect (Figure 2A). The lesion was barely visible in supine position and could be com-pletely reduced upon compression with the ultrasound probe (Figure 2B). The muscle protrusion appeared more pronounced in standing position (supplementary video). Clinical examination and imaging were characteristic of peroneus longus muscle herniation.CommentMuscle herniation consists of a focal muscle protrusion through a myofascial defect [1]. The fascia defect may be either congenital or acquired. The most commonly Dierickx J, Vanhoenacker F. Muscle Herniation: An Often-Missed Pseudotumor. Journal of the Belgian Society of Radiology. 2020; 104(1): 62, 1–3. DOI: https://doi.org/10.5334/jbsr.2294* AZ Sint-Maarten, BE† University (Hospital) Antwerp/Ghent, BECorresponding author: Filip Vanhoenacker (filip.vanhoenacker@telenet.be)IMAGES IN CLINICAL RADIOLOGYMuscle Herniation: An Often-Missed PseudotumorJesper Dierickx* and Filip Vanhoenacker*,†Teaching Point: Dynamic ultrasound and knowledge of a clinical history of a soft-tissue lump that increases in volume upon muscle contraction or weight-bearing are crucial in the diagnosis of muscle herniation. Keywords: muscle herniation; ultrasound; magnetic resonance imagingFigure 1.Dierickx and Vanhoenacker: Muscle HerniationArt. 62, page 2 of 3 affected muscles are the tibialis anterior, extensor digito-rum longus, peroneus longus and brevis, gastrocnemius, and the forearm flexors [1].On clinical examination, the lesion usually presents as a painless palpable swelling and is more prominent and harder upon muscle contraction. In some cases, it may be painful during exercise. Dynamic ultrasound is the preferred imaging modality when muscle herniation is suspected. Ultrasound during contraction or in standing position demonstrates volume increase through the myo-fascial defect compared to ultrasound during rest. Extensive compression with the ultrasound probe may reduce the muscle protrusion. Therefore, a technique of graded ultra-sound compression and alternated muscle relaxation is rec-ommended. On dynamic MRI with muscle contraction and relaxation, a bulging muscle contour with a focal fascial dis-ruption may be rarely seen. It is often not recognized due to its supine position. In an uncomplicated muscle herniation, the protruded muscle tissue demonstrates iso-intense sig-nal intensity to non-herniated muscle tissue. Hyperintense signal in the herniated muscle tissue on T2-WI corresponds to muscle edema or fascial tearing [1].Treatment is not necessary in asymptomatic patients. Activity restriction and support stockings may relieve mild symptoms. Surgical treatment, such as wide fasciotomy, is only required in patients with severe symptoms [1].In conclusion, radiologists should be aware of the typical clinical history of the patient. For correct diag-nosis, a high index of suspicion and dynamic ultra-sound using graded compression and contraction are mandatory.Additional FileThe additional file for this article can be found as follows:•	 Supplementary Video. Dynamic ultrasound (longi-tudinal view) in standing position shows disappear-ance of the muscle herniation upon compression  with the ultrasound probe. DOI: https://doi.org/10.5334/jbsr.2294.s1Competing InterestsThe authors have no competing interests to declare.Reference 1. Yochim SE, Jose J, Clifford PD. Muscle hernia-tion of the extremity. Am J Orthop. 2010; 39(2): 95–6. Figure 2.Dierickx and Vanhoenacker: Muscle Herniation Art. 62, page 3 of 3 How to cite this article: Dierickx J, Vanhoenacker F. Muscle Herniation: An Often-Missed Pseudotumor. Journal of the Belgian Society of Radiology. 2020; 104(1): 62, 1–3. DOI: https://doi.org/10.5334/jbsr.2294Submitted: 30 August 2020        Accepted: 26 October 2020        Published: 13 November 2020Copyright: © 2020 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See http://creativecommons.org/licenses/by/4.0/.                           OPEN ACCESS Journal of the Belgian Society of Radiology is a peer-reviewed open access journal published by Ubiquity Press.

Muscle herniation : an often-missed pseudotumor

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Muscle herniation : an often-missed pseudotumor

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