What is the best course of action for a 44-year-old male patient with a 2.0 cm movable and deep mass on the medial aspect of his right arm, presenting with tingling and numbness, and scheduled for an ultrasound (US) to rule out nerve involvement?

From the Guidelines

The best course of action for this 44-year-old male patient is to proceed with the scheduled ultrasound to evaluate the 2.0 cm movable deep mass on the medial aspect of his right arm, followed by referral to a surgeon for excisional biopsy, as recommended by the most recent guidelines 1. The presence of tingling and numbness suggests possible nerve involvement, which makes the ultrasound essential to determine if the mass is compressing or involving a nerve (likely the median or ulnar nerve given the location). After imaging, surgical consultation is warranted regardless of ultrasound findings, as the definitive diagnosis requires histopathological examination. The differential diagnosis includes benign tumors like lipoma, neurofibroma, or schwannoma, but malignant soft tissue sarcoma must be ruled out, and according to the UK guidelines for the management of soft tissue sarcomas 1, a pre-treatment histopathological diagnosis should be made, if possible, by percutaneous core biopsy. While waiting for the ultrasound and surgical evaluation, the patient can be prescribed NSAIDs such as ibuprofen 400-600 mg three times daily for discomfort, but should avoid local manipulation of the mass. The patient should be advised that complete excision with negative margins is typically curative for benign lesions, while malignant tumors would require more extensive treatment, and early intervention is important as continued growth could increase nerve compression symptoms and potentially complicate surgical management, as highlighted in the guidelines for the management of soft tissue sarcomas 1. It is also important to note that cross-sectional imaging of the primary tumour, usually in the form of magnetic resonance imaging (MRI) is recommended prior to definitive surgery, as stated in the UK guidelines for the management of soft tissue sarcomas 1. In addition, the patient should be managed by a specialist Sarcoma MDT as specified in the NICE guidance, to ensure the best possible outcome. Ultrasound provides an effective initial triage tool, and in certain conditions such as soft tissue arterio-venous malformations, may demonstrate pathognomonic features, as mentioned in the UK guidelines for the management of soft tissue sarcomas 1. However, it is crucial to remember that ultrasound assessment is highly user dependent, and therefore in the case of diagnostic uncertainty, an MRI of the affected region should be performed, as recommended by the guidelines 1. The use of ultrasound as the initial diagnostic imaging method in assessment of soft-tissue masses has been increasing, and it has proved to be most useful when applied to evaluation of small superficial lesions, typically those superficial to the deep fascia, as stated in the ACR appropriateness criteria for soft-tissue masses 1. But in this case, since the mass is deep and movable, an MRI might be more appropriate for further evaluation, if the ultrasound findings are uncertain, as recommended by the guidelines 1.

From the Research

Patient Presentation

• The patient is a 44-year-old male with a 2.0 cm movable and deep mass on the medial aspect of his right arm.
• The mass is approximately 1.5 cm deep and the patient is experiencing tingling and numbness in his right arm.
• The patient believes the symptoms are related to the mass.

Diagnostic Approach

• An ultrasound (US) has been ordered to rule out nerve involvement 2.
• US is an ideal triaging tool for superficial soft tissue masses and can readily identify and exclude benign lesions such as lipomas and ganglia 2.
• The patient's symptoms of tingling and numbness suggest the possibility of nerve involvement, which can be evaluated using US.

Differential Diagnosis

• Lipoma: a benign skin tumor composed of mature fat cells, which is the most common subcutaneous tumor 3.
• Other benign tumors: such as epidermal inclusion cysts, which can also present as a movable mass 3.
• Soft tissue tumors: which can be benign or malignant, and may require further evaluation with MRI and biopsy if suspected to be malignant 2, 4.

Management

• If the US suggests a benign lesion such as a lipoma, the patient may be referred for surgical excision or alternative treatment options such as intralipotherapy 5.
• If the US suggests nerve involvement or a malignant tumor, the patient may require further evaluation with MRI and biopsy, and management by a multidisciplinary team involving specialized surgeons and pathologists 2, 4.
• The patient's symptoms and clinical presentation will guide the need for further evaluation and management.