CASE 14975 Published on 02.11.2017

Nodular fasciitis of the wrist simulating carpal tunnel syndrome

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

P.Hernandez Mateo

Hospital Clinico San Carlos,Radiology Department; C/Profesor Martin Lagos SN 28040 Madrid, Spain; Email:phmaula@gmail.com
Patient

50 years, female

Categories
Area of Interest Extremities, Musculoskeletal soft tissue ; Imaging Technique Ultrasound-Power Doppler, MR
Clinical History
A 50-year-old patient with suspected carpal tunnel syndrome had an MRI performed. A soft tissue mass involving the median nerve and the flexor retinaculum was reported.
Imaging Findings
The ultrasound revealed an hypoechoic lesion at the volar side of the hand surrounding the flexor tendons, and Doppler colour showed rich vascularisation of the lesion (Fig 1).
An MRI was performed demonstrating a rounded lesion surrounding the flexor tendons of the hand and also the median nerve. At the T1-weighted image it proved to be little hyperintense compared to the muscle (Fig. 2), and hyperintense at T2 Fat-sat weighted image (Fig 2). After injection of gadolinium the lesion showed avid peripheral enhancement (Figs. 4 and 5), maybe due to the myxoid component located in the middle of the lesion. All these findings suggested a soft tissue tumour or a tumour-like lesion, therefore a biopsy was recommended.
Discussion
Nodular fasciitis is the most common benign tumour or tumour-like lesion of fibrous tissue. It usually affects adults between 20-40 years-old and the most common location is the upper extremity, particularly the volar aspect of the forearm. This benign entity is a common pseudosarcomatous fibroblastic proliferation of unknown origin, probably representing a reactive lesion secondary to trauma and recently proved to be a true neoplastic origin due to a chromosomal mutation [1-3].

Pathological diagnosis of nodular fasciitis can be challenging, as these lesions, with their rich cellularity, high mitotic activity, and rapid growth, can mimic aggresive tumours as soft tissue sarcomas [1, 3, 4]. Histologically it can be categorised as myxoid, cellular, or fibrous, according to the predominant histologic feature of the lesion.

There are three described subtypes of nodular fasciitis based on the location of the lesion: subcutaneous, intramuscular, or fascial. The most frequent location of nodular fasciitis is the subcutaneous region being usually fascial lesions with well circumscribed margins easy to biopsy or excision. Lesions of the intramuscular and some fascial subtypes are usually larger, tend to be deeper and have poorer delimited margins conferring an aggressive appearance and mimicking soft-tissue malignancies [1, 3, 4].

As nodular fasciitis can present with a wide range of histological features, these lesions have variable MR imaging appearances, but are usually isointense to the skeletal muscle on T1-weighted images and hyperintense to adipose tissue on T2-weighted images.
Lesions with a predominant fibrous component may have a hypointense signal on all MR images. Postcontrast sequences show typically diffuse enhancement but it may be peripheral in lesions with myxoid matrix or a central fluid-filled component [1, 3, 4].

Surgery is almost curative in all cases only being reported a 1% incidence of recurrence [1, 3, 4]. Involution and spontaneous regression has also been described as the natural history of the disease [3] of nodular fasciitis in response to steroid injections have also been reported [5].

Finally the patient of our case underwent surgery with total excision and reconstruction. No recurrence has been reported since surgery.
Differential Diagnosis List
Fascial nodular fasciitis
Extra-abdominal desmoid tumour
Neurofibroma
Fibrous histiocytoma
Soft tissue sarcoma
Final Diagnosis
Fascial nodular fasciitis
Case information
URL: https://www.eurorad.org/case/14975
DOI: 10.1594/EURORAD/CASE.14975
ISSN: 1563-4086
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