Hip pain attributable to a ganglion of the psoas tendon: a common cyst in an uncommon region—the first case reported in a child
- 1 Trauma and Orthopaedics, University hospital of Wales healthcare NHS trust, Cardiff, UK
- 2 Radiology, University hospital of Wales, Cardiff, UK
- 3 Trauma and Orthopaedics, University hospital of Wales, Cardiff, UK
- Correspondence to Dr Sandeep Gokhale; drsandeepgokhale@gmail.com
Abstract
Ganglion cysts of the psoas tendon are uncommon and rarely reported in the literature. Often they remain asymptomatic and are found incidentally or can be a cause of atypical groin/hip pain. We present a rare case of ganglion cyst in a child arising from the psoas tendon, causing symptomatic hip pain, which failed non-surgical treatment and eventually successfully treated with surgical excision.
Background
Ganglia most commonly present on the dorsum of the wrist.1 They are a benign cystic mass of unknown origin, densely surrounded by connective tissue network containing mucopolysaccharides and hyaluronic acid.2 We present the first case in a child who had a symptomatic psoas tendon ganglion, who failed non-surgical management (physiotherapy to include warm-up and stretching before and after sporting activity, analgesics) and was subsequently successfully treated surgically.
Case presentation
A 9-year-old girl presented with right-sided hip pain (primarily anterior and groin region) of 7 months duration. The pain was insidious in onset, dull aching, not associated with fever, night pain, weight loss, rash or other joint involvement. There was no history of any specific trauma. The pain was aggravated on sporting activity, particularly during running, jumping and landing.
Clinical examination demonstrated full and symmetrical range of motion in both hips. The pain was reproduced in the figure of four position on right side. No palpable mass or swelling was detected. The rest of the spine, pelvis and lower limb examination were normal.
Investigations
Plain radiographs of pelvis with both hips were normal, with no evidence of dysplasia and normal neck-shaft angles of the femur.
The blood investigations were normal, with no rise in inflammatory markers.
An MRI scan of the right hip (figures 1 and 2A) showed a linear, multiloculated ganglion cyst, anterior to the hip joint closely applied to anterior joint capsule, measuring 4 cm in craniocaudal dimension. It was superficial to the right iliofemoral ligament and extended superiorly to the pelvic brim. The right acetabular labrum and right rectus femoris tendon were normal, thus excluding the possibility of labral tear or paralabral cyst.
Coronal short tau inversion recovery image (A) of the pelvis and axial proton density fat saturated image (B) of the right hip. The cyst is visible (white arrows) adjacent to the right anterior inferior iliac spine and the right rectus femoris tendon (white arrowhead in A) and deep to the right iliopsoas muscles (white arrowheads in B).
Sagittal proton density image with fat saturation (A), and ultrasound image (B) of the right hip obtained before aspiration. The cyst is elongated with several loculations. There is good correlation of morphology and extent of the cyst between modalities. It is seen deep to the right iliopsoas muscles (white arrowheads) and superficial to the right femoral head/neck (F).
Treatment
Considering the duration of pain and nature of the cyst, it was decided to attempt ultrasound (US)-guided aspiration with local injection of 40 mg methylprednisolone acetate and 0.25% bupivacaine (figure 2B). She reported complete pain relief for 2 months postprocedure but symptoms recurred thereafter.
A follow-up US scan at 3 months demonstrated reaccumulation of the cyst. US-guided aspiration and steroid injection were repeated but symptoms recurred within 4 weeks.
After a multidisciplinary review involving radiologists and paediatric surgeons, it was planned to conduct an excision biopsy. This would help to alleviate her symptoms as well as establish a definitive diagnosis.
A limited bikini incision was used centred a finger breadth below the anterior superior iliac spine; sartorius identified and dissection medially to isolate iliopsoas. Cystic changes were found along the psoas tendon and sheath (figure 3). The cyst and sheath of the psoas tendon were excised and sent for histology, and the tendon was released.
Intraoperative image of ganglion along psoas tendon.
Histopathology report confirmed myxomatous degeneration consistent with diagnosis of a ganglion cyst.
Outcome and follow-up
Subsequent clinical assessment 12 months postsurgery demonstrated complete resolution of symptoms and she was able to participate in sports activities.
Discussion
Ganglion cysts are common benign lesions commonly found around small and large joints.3 The usual composition of ganglion cyst consists of high-degree viscous gelatinous material with mucopolysaccharides and hyaluronic acid.2 Surprisingly, the origin of the ganglion remains unclear. Some of the theories are (a) simple herniation of joint capsule results in cyst, (b) ‘capsular rent’ theory, (c) joint stress, leading to mucoid degeneration of periarticular connective with subsequent fluid collection and eventual cyst formation and, finally, (d) joint stress might invigorate mucin secretion by mesenchymal cells.2 The ultimate common pathway of the proposed theories is coalescence of droplets of mucin, leading to formation of main cyst.2
Ganglions frequently occur on the dorsal surface of wrist (60%–70%)1 and are uncommon around the hip. Cystic lesions are incidentally found in up to 26% of asymptomatic patients during imaging studies of the hip.4 These include synovial cyst, ganglion cyst, bursae and paralabral cysts.5 When associated with the hip, they are closely linked to pathologies such as osteoarthritis, rheumatoid arthritis, trauma, avascular necrosis of femoral head and total hip arthroplasty.4 Psoas ganglia are rare, with a few adult case reports, for example, Beardsmore et al reported psoas ganglion in a 55-year old, causing obstruction of iliofemoral arteries.6 7 Unusual sites around the hip include pyriformis muscle,8 anterior to hip joint,9 synovial ganglion of hip causing L5 radiculopathy,10 arising from transverse acetabular ligament, causing compression of obturator nerve.11 All of these have been reported within the adult population and none in the paediatric age group.
US is the first-line investigation for many paediatric musculoskeletal disorders, including soft tissue lesions. It is readily available in most centres and does not involve the use of ionising radiation. It is well tolerated by most paediatric patients and is capable of distinguishing cystic from non-cystic lesions.5 It allows dynamic assessment of musculoskeletal structures and can guide interventions (aspiration, biopsy, therapeutic injection).
MRI is considered the gold-standard investigation to demarcate and characterise soft tissue lesions due to its exceptional soft tissue contrast sensitivity and multiplanar capabilities.5 Appropriate sequences can provide a definitive diagnosis in some situations, and it facilitates distinction between benign and malignant soft tissue tumours, with reported sensitivity and specificity of up to 95%.
Therapeutic approaches to cystic lesions of the hip depend on the location, size, symptoms, existence or non-existence of local compression and the suspected pathological nature. Asymptomatic cysts can be observed.4 12 In the case of painful and enlarged cysts, symptomatic relief may be achieved by rest, non-steroidal anti-inflammatory drugs and physical therapy. Needle aspiration and subsequent injection of local anaesthetic along with corticosteroid are second-line treatment option with 87% resolution rate13 associated with less morbidity than open surgical excision.4 14
Cysts that arise in association with intra-articular labral pathology are well described in adolescents. Intra-articular pathology causing hip pain should always be considered and MRI imaging useful to exclude this.15
Cysts that cause symptoms due to local compression of neurovascular structures can either be treated by aspiration or surgical excision. Recurrence can be avoided by dependable method of surgical excision.4 16
Patient’s perspective
As the child’s father was a medical staff with the knowledge of risks associated with surgical intervention, the family opted for minimal invasion for the treatment in the form of ultrasound-guided aspiration on two occasions. Joint decision by the family and surgical team was made for surgical intervention after recurrence on the second ultrasound-guided aspiration. The family and the child are both very happy with our surgical treatment, which alleviated the symptoms.
Learning points
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High index of suspicion in unresolving joint pains in children.
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MRI is an important investigating modality aiding in detection of rare and unusual conditions.
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Differential diagnosis of labral tear, paralabral cysts, juvenile idiopathic arthritis causing iliopsoas bursitis should be kept in mind, and necessary investigations should be carried out to rule them out.
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This is the first case of a symptomatic psoas ganglion cyst reported in the paediatric age group, which exhausted non-surgical options and was treated with successful surgical excision.
Ethics statements
Patient consent for publication
Footnotes
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Contributors SG contributed in research and drafting the article. PM contributed in diagnostics and research. PT and ECC were the surgeons who treated the patient.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Competing interests None declared.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2021. No commercial re-use. See rights and permissions. Published by BMJ.
References
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