A 44-year-old male patient presented with a history of several months of mechanical left shoulder pain. Physical examination showed preserved range of motion and muscle strength. The patient's past medical history was unremarkable.
Anteroposterior radiography revealed a well-defined lytic lesion affecting the scapula. The lesion showed a narrow transition zone with a thin sclerotic rim. No cortical destruction, periosteal reaction or matrix formation was observed. (Figure 1)
Magnetic Resonance Imaging (MRI) examination confirmed a solid, round and very well-defined soft tissue mass (3.5 x 2.8 x 2.4 cm) with epicentre in the spinoglenoid notch. There was also large remodelling of the underlying scapula that preserved a rim of very thin cortical rest.
The lesion had an intermediate signal intensity on T1-weighted images (WI) (Figure 2), hyperintense on the T2-WI (Figures 3) and an homogeneous enhancement after administration of Gadolinium (Figure 4).
A close relationship between the tumor and the suprascapular nerve was observed, but contiguity of both structures was not clearly shown (Figure 2).
There was no evidence of muscle atrophy, fatty infiltration or oedema suggesting denervation.
A CT-guided biopsy yielded the diagnosis of schwannoma (Figure 5).
Solitary benign peripheral nerve sheath tumours may be subdivided into schwannomas (neurilemmoma) and neurofibromas.
In up to 90% of the cases, both schwannomas and neurofibromas correspond to solitary lesions not associated with neurofibromatosis type 1. On the other hand, Neurofibromatosis type 1 presents almost invariably multiple neurofibromas, with visceral and deep nerve involvement and an increased risk of malignant transformation.
Schwannomas are composed primarily of Schwann’s cells and they are eccentrically located in relation to the involved nerve, presenting a true capsule composed of epineurium; they can be generally separable from the underlying nerve fibres.
In contrast, neurofibromas are centrally located, rarely encapsulated, and cannot be separated from the nerve [1, 2].
Schwannomas affect patients between 20–40 years old, and represent approximately 5% of benign soft-tissue neoplasms. They usually appear as a painless slow-growing soft-tissue mass, and symptoms may initiate when the lesion become large enough to compress the adjacent nerve [1].
MRI features of schwannomas consist of iso or low-signal-intensity lesions on T1-WI, high-signal-intensity lesions on T2-WI, and avid contrast enhancement.
The lesion generally shows fusiform shape oriented longitudinally and with tapered ends contiguous to the nerve of origin.
The lesion may show a characteristic “target sign” on T2-WI, with a central hypointense region, or the “split-fat sign” that represents a rim of fat surrounding the margins of the nerve sheath tumour, especially when it has an intermuscular location.
Imaging findings in many cases do not allow differentiation between schwannomas and neurofibromas, and the fusiform shape, the “split-fat sign”, and the “target sign” can be seen in both [3].
When the schwannomas are in close relation to a bone, it is often difficult to determine whether it is a soft tissue schwannoma involving the bone or an intraosseous schwannoma involving the surrounding soft tissues [4], but this last is less frequent. In this patient the tumour causes secondary remodelling of the bone due to the slow growing pattern.
Surgical excision is the treatment of choice for schwannomas, and the lesion is usually separable from the native nerve allowing the preservation of the rest of the nerve fibres and their function. Recurrence is rare and malignant transformation is extraordinarily unusual [1].
Take Home Points:
Soft tissue schwannoma may debut with the appearance of a benign bone solitary lesion due to its proximity to bones and its slow-growing pattern. A peripheral nerve sheath tumor may be included in the differential diagnosis of any well-defined mass in close relation to a nerve.
Schwannoma of a branch of the suprascapular nerve mimicking a bone tumor.
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Based on the comprehensive evaluation of the left shoulder X-ray and MRI images, a well-defined soft tissue mass is seen in the periscapular region (subacromial area or near the glenoid). The X-ray shows that this mass causes distinct “pressure” or “remodeling” of the adjacent scapula, with localized thinning or mild bulging of the bone, suggesting a slowly growing lesion exerting long-term pressure on the osseous structure.
MRI plain and contrast scans indicate:
1. On T1-weighted images (T1WI), the lesion appears isointense or slightly hypointense compared to muscle.
2. On T2-weighted images (T2WI), it appears hyperintense, with possible “target sign” or “split-fat sign” (i.e., a fat plane around the tumor).
3. After contrast enhancement, the mass shows marked enhancement, appearing fusiform or nearly round, with a clear boundary from surrounding soft tissues.
4. The tumor is closely related to the neural structures, but most nerve fibers are not fully involved. The mass grows eccentrically on one side of the nerve bundle.
5. The lesion grows slowly without obvious invasive changes or extensive soft tissue destruction.
Considering the patient’s age (44 years), symptoms (chronic left shoulder mechanical pain), imaging findings (a soft tissue mass with a well-defined capsule, eccentric growth, easily separated from nerve fibers, T2 hyperintensity with marked enhancement), and potential intraoperative or biopsy pathology, the summary is as follows:
Most likely diagnosis: Schwannoma (Neurilemmoma, a benign peripheral nerve sheath tumor).
If a definitive diagnosis is still required, surgical resection followed by pathological examination can rule out other rare nerve-origin or soft tissue tumors.
If the patient has osteoporosis, poor cardiopulmonary function, or other comorbidities, the training intensity and methods should be adjusted under the guidance of healthcare professionals. Any discomfort during postoperative rehabilitation should be closely monitored to ensure safety.
Disclaimer:
This report is based solely on the currently provided medical history and imaging information, aiming to offer a reference for medical analysis. The specific diagnosis and treatment plan should consider the patient’s actual condition and be finalized by a qualified clinical physician after an in-person evaluation. This report does not replace a doctor’s direct diagnosis or medical decision-making.
Schwannoma of a branch of the suprascapular nerve mimicking a bone tumor.
