The patient had a 10-year history of a slowly enlarging soft tissue growth on the right thenar eminence, studied with US and MRI.
The patient had a 10-year history of a slowly enlarging soft tissue growth on the right thenar eminence; in the previous year the growth size had increased rapidly. His past medical history was unremarkable and there was no family history of cancer or tumour.
The patient presented with paraesthesia on the right thumb thenar eminence. Ultrasound (US) examination revealed an inhomogeneous solid mass, 3 x 5 x 6 cm, located inside the muscle, well encapsulated, clearly distinguished from surrounding normal structures (Fig. 1). The US pattern was not specific.
MR imaging was performed, acquiring on axial, coronal and sagittal planes, using spin echo (SE) T1- and T2-weighted sequences and short T1 inversion recovery (STIR) sequences, using the following parameters: SE T1-weighted sequences with TR/TE, 620/24; SE T2-weighted sequences with TR/TE, 2030/80; STIR sequences with TR/TE, 1400/16; number of excitation, 1; slice thickness, 3-4mm; and gap, 0.3mm. The MR imaging showed a clear-bordered mass with regular edges, with intermediate signal intensity on T1-weighted sequences (Fig. 2a), and high signal intensity on T2-weighted (Fig. 2b) and STIR (Fig. 2c) sequences. SE T1-weighted sequences after i.v. 20ml gadolinium administration, showed marked enhancement of the lesion with a hypointense area inside (Fig. 2d). There was no involvement of the surrounding anatomical structures.
The patient underwent surgical treatment, enucleating a well-encapsulated mass (Fig. 3). Histological examination of the pathological specimen allowed the diagnosis of a benign Schwannoma.
Schwannoma, also referred to as neurilemmoma, is the most common solitary nerve tumour. It was first studied in 1949 by Stout, who described it as a benign proliferation of the Schwann cells [1]. The tumour is well encapsulated and minimally symptomatic; it rarely disturbs the function of the involved nerve and can be easily surgically enucleated.
Schwannoma typically arise from peripheral nerves (upper and lower extremities, cranial and intercostal nerves), while hand involvement is rare. The reported incidence in the hand isbetween 3.5% and 7.2% [1-3]. Although this localisation is rare, when an expansive soft tissue lesion of the hand is present, Schwannoma must be included in the differential diagnosis.
Clinical examination is not specific; because of its cystic consistency, a Schwannoma in the hand may be mistaken for a ganglioma. The US pattern is not specific showing a homogeneous or intermediately inhomogeneous, well-encapsulated, solid mass. MR findings are more characteristic since frequently Schwannoma displays intermediate to high signal intensity on T1-weighted sequences with marked enhancement after gadolinium i.v. and high signal intensity on T2-weighted sequences [4-5].
Even though a definite diagnosis can be established only by histological examination, US and MRI are important because they allow a rapid differential diagnosis between solid and cystic lesions, defining dimensions, limits, morphology, and connections with nearby tissues. They are also useful in the follow-up. Furthermore MRI “target” is rarely seen in schwannomas but mostly described in neurofibromas, nevertheless the presence of this pattern is very important because can consent a differential diagnosis with malignant peripheral nerve sheath tumor (MPNST).
Schwannoma
Based on the ultrasound (US) and magnetic resonance imaging (MRI), the following observations are noted:
Considering the patient’s slow-growing mass over more than ten years and the imaging characteristics, the primary differential diagnoses include:
Considering the clinical history and imaging aspects, a schwannoma is the most likely diagnosis.
Taking into account the patient’s age, the long-standing history of slow-growing mass (over a decade), the imaging features (a well-defined, encapsulated lesion showing high T2 signal and contrast enhancement), and possible confirmation via postoperative or pathological examination, the most probable final diagnosis is:
Schwannoma
1. Treatment Strategy
2. Rehabilitation and Exercise Prescription
Hand rehabilitation following soft tissue surgery is essential for functional recovery. The gradual approach follows the FITT-VP principle:
When managing patients with osteoporosis, cardiovascular compromise, or other comorbidities, tailor the rehabilitation intensity and methods accordingly under the guidance of rehabilitation professionals and physicians.
3. Additional Precautions
This report is based solely on the available patient history and imaging findings for a preliminary analysis. It is not a substitute for an in-person consultation or professional medical advice. In case of any new symptoms or abnormal findings, please seek professional medical care promptly.
Schwannoma
