E56 A 16-year diagnosis delay of a patient with Pigmented Villonodular Synovitis
Authors: Mwangangi Musenya E , Kaniu Mary , Migowa Angela 
Published: August 2023

Abstract

Introduction
Pigmented villonodular synovitis (PVNS), a subtype of tenosynovial giant cell tumours, is a rare non-cancerous proliferative synovial disorder usually affecting the knee in adults(1). The incidence rate is 1.8 patients per million people of the general population, with few reports amongst the paediatric population, hence it is frequently misdiagnosed(2). It has a slow onset of symptoms and has been noted to take ∼18 months to make a definitive diagnosis(3).

Objective
To describe a case of pigmented villonodular synovitis in a seventeen-year-old African female.

Methods
A retrospective chart review was done to ascertain the clinical presentation and management of the patient.

Case description
We present a case of a 17-year-old African female who presented with bilateral knee pain and swelling from 10 months of age. She had been on follow-up at a peripheral facility for 14 years, where she was being managed with methotrexate 12.5 mg weekly and folic acid 5 mg OD for Juvenile Idiopathic Arthritis with no marked improvement in her symptoms. In view of her poor response to therapy, the mother stopped her treatment 3 months prior to presentation in our facility.
She initially had intermittent bilateral swelling of the small joints of the hand that were tender which eventually evolved to involve both knee joints. The pain was worse in the morning and was associated with the inability to ambulate and occasional night awakening. The systemic inquiry was otherwise unremarkable. She had an unremarkable birth history, and normal developmental milestones. She was however shorter than her peers and had not attained menarche.
The patient had been admitted 8–10 times per year during the span of her illness for similar complaints and had undergone multiple knee joint fluid aspirations to relieve the swelling and several laboratory tests and radiological studies were done.
On assessment, she was noted to be of fair general condition with gross asymmetric swelling of both knees and a surgical scar over the right knee with no limitation in the range of movement. There was minimal effusion of bilateral elbows and ankles, and the MCP, ICP and wrist joints weren’t affected. The patient had thoracic scoliosis, a grade 3/6 systolic murmur on the left lower sternal border, no radiation, and hepatomegaly 4 cm below the costal margin. She was prepubertal on sexual maturation rating. There was no central nervous system, abdominal, or respiratory abnormalities. A series of lab investigations to exclude the possibility of juvenile idiopathic arthritis were conducted. This panel included a complete blood count, which showed hypochromic, microcytic anaemia, c-reactive protein was raised at 61 mg/l but normal biochemistry and unremarkable autoantibody profile.
Imaging done included a bilateral knee X-Ray followed by a bilateral knee MRI which showed large volume bilateral knee joint effusions associated with synovial-based masses causing extrinsic periarticular bony erosions and intra-articular synovial proliferation forming a villonodular appearance.
The patient was referred to orthopaedic surgery and bilateral arthrotomy, drainage and synovectomy of both knees were done. She continues to be followed up in our paediatric rheumatology and orthopaedic clinic with good mobility and no other co-morbidities. She is currently undergoing work up for a delayed puberty.

Conclusion
Pigmented villonodular synovitis is a rare disease in the paediatric population. In the absence of awareness of its existence and expertise on how to diagnose it, patients may be misdiagnosed and mismanaged over a long duration of time as seen in the presented case.

References
1. Fecek C CK. Pigmented Villonodular Synovitis. StatPearls Publishing. 2022 Jan. https://wwwncbinlmnihgov/books/NBK549850
2. Baroni E, Russo BD, Masquijo JJ, Bassini O, Miscione H. Pigmented villonodular synovitis of the knee in skeletally immature patients. Journal of Children's Orthopaedics. 2010; 4(2):123–7.
3. Cook NS, Landskroner K, Shah B, Walda S, Weiss O, Pallapotu V. Identification of Patient Needs and Preferences in Pigmented Villonodular Synovitis (PVNS) Using a Qualitative Online Bulletin Board Study. Advances in Therapy. 2020; 37(6):2813–28