From the Guidelines
I strongly recommend proceeding with an urgent ultrasound evaluation of the rapidly growing mass on the patient's right lower back, as suggested by the UK guidelines for the management of soft tissue sarcomas 1. The concerning features of this case include the rapid growth from ping pong ball to tennis ball size in just two months and the pain that disrupts the patient's sleep. While the mass feels mobile like a lipoma on palpation, the unusually fast growth rate raises concerns for other possibilities including potentially malignant soft tissue tumors. Key points to consider in the management of this patient include:
- The clinical presentation of a rapidly growing soft tissue mass, which is a common presentation of soft tissue sarcomas 1
- The importance of early diagnosis and referral to a specialist sarcoma unit, as emphasized by the NICE guidelines 1
- The role of ultrasound as an initial triage tool for soft tissue masses, and the potential need for further imaging with MRI or CT scans if the ultrasound findings are uncertain or concerning 1 After the ultrasound, if the mass appears complex or has concerning features, an MRI may be needed for better tissue characterization. Given the symptoms and growth rate, surgical excision with pathological examination will likely be necessary regardless of imaging findings. The patient should be advised to avoid trauma to the area while awaiting further evaluation, and temporary pain management with acetaminophen or NSAIDs may be appropriate until definitive treatment. Early intervention is important as rapidly growing soft tissue masses require prompt diagnosis and management, as highlighted by the UK guidelines for the management of soft tissue sarcomas 1. It is also important to note that the diagnosis of soft tissue sarcomas can be challenging, and a multidisciplinary approach involving specialist sarcoma units and pathologists is often necessary to ensure accurate diagnosis and effective management 1. In addition, the patient's symptoms and medical history should be carefully evaluated to determine the best course of treatment, and to rule out other potential causes of the mass, such as lipomas or other benign tumors 1.
From the Research
Patient Presentation
- The patient is a 48-year-old male presenting with a mass on his right lower back, initially noticed in March 2025.
- The mass has grown rapidly from the size of a ping pong ball to the size of a tennis ball in two months.
- The mass is movable and painful, especially when the patient rolls onto that side at night.
Diagnostic Approach
- An ultrasound of the affected area has been prescribed to determine the nature of the mass and assess potential complications.
- The ultrasound will help guide further management and potential interventions.
Relevant Studies
- A study published in 2018 2 highlights the importance of understanding the diagnostic magnetic resonance imaging appearance of lipomatous soft-tissue tumors to avoid unplanned excisions of sarcomas.
- A 2020 study 3 found that ultrasound depth is a significant predictor of a histologically non-benign lipoma, and that ultrasound signs are more predictive of post-operation histology outcome than clinical signs or MRI tests.
- Another 2020 study 4 suggests that routine preoperative core needle biopsy based on mass size may not be necessary, and that radiographic features can guide the need for biopsy.
- A 2024 study 5 found that contrast-enhanced ultrasound can reveal perfusion differences between benign lipoma and semi-malignant atypical lipomatous tumors, potentially enhancing diagnostic accuracy.
Potential Diagnoses
- Benign lipoma
- Atypical lipomatous tumor
- Liposarcoma
- Other soft tissue tumors
Next Steps
- Ultrasound evaluation to determine the nature of the mass and assess potential complications.
- Potential biopsy or further imaging studies based on ultrasound results.
- Referral to a sarcoma referral center if necessary, as recommended by the 2018 study 2.