What is the next step in managing a non-tender, smooth, mobile, firm lump on the back of the neck, consistent with a lipoma (fatty tumor), in a patient with a history of lipomas (fatty tumors)?

From the Guidelines

The next step for a patient with a non-tender, smooth, mobile, firm lump on the back of the neck that has been present for a year, with a history of lipomas and characteristics consistent with a lipoma, would be to consider watchful waiting with periodic monitoring or referral for surgical excision if the patient desires removal. Since the mass has been stable for a year and has features typical of a benign lipoma (being mobile, smooth, and non-tender), immediate aggressive intervention is not necessary. However, if the patient is concerned about the appearance, experiences discomfort, or wants definitive diagnosis, surgical excision can be performed as an outpatient procedure under local anesthesia. The excised tissue should be sent for pathological examination to confirm the diagnosis. Alternatively, if there is any uncertainty about the diagnosis, an ultrasound or MRI could be ordered to better characterize the mass before deciding on excision, as suggested by the UK guidelines for the management of soft tissue sarcomas 1. Lipomas are benign fatty tumors that typically grow slowly and rarely become malignant, which is why observation is often appropriate when clinical features are characteristic and the patient is asymptomatic. It's also important to differentiate between lipoma and atypical lipomatous tumours (ALT), also known as well-differentiated liposarcoma (WDL), as the latter has the propensity for local recurrence, although dedifferentiation into a more aggressive disease is extremely rare 1. MRI with expert review can help differentiate between large, deep lipomas and ALT/WDL, and the defining diagnostic test is the molecular demonstration by fluorescence in-situ hybridisation of amplification of the MDM-2 cell cycle oncogene 1. In any case, the approach should prioritize the patient's quality of life, morbidity, and mortality, and the decision for watchful waiting or surgical excision should be made on a case-by-case basis, taking into account the patient's preferences and values. Some key points to consider in the management of this patient include:

• The use of ultrasound or MRI to characterize the mass if there is any uncertainty about the diagnosis 1
• The importance of differentiating between lipoma and ALT/WDL, as the latter may require a different surgical approach 1
• The role of molecular testing in confirming the diagnosis of ALT/WDL 1
• The need for a multidisciplinary approach to manage soft tissue sarcomas, including input from radiologists, pathologists, and surgeons 1

From the Research

Next Steps for Diagnosis

The patient presents with a lump on the back of the neck, which has been present for a year, and is described as non-tender, smooth, mobile, and firm. Given the patient's history of lipomas, this lump is consistent with a lipoma.

• The size of the lump is not specified, but according to the study 2, lipomatous masses smaller than 5 cm without concerning clinical characteristics do not require preoperative imaging or core needle biopsy (CNB).
• If the lump is larger than 5 cm, or if there are concerning clinical characteristics, MRI with subsequent CNB may be necessary if multiple high-risk radiographic features are present 2.
• Fine needle aspiration biopsy (FNAB) may be considered as an initial diagnostic sampling procedure, as it has been shown to be cost-effective and have a high cancer yield 3.
• Ultrasound-guided core biopsy or FNAB may be used to evaluate axillary lymphadenopathy in patients with breast cancer, with core biopsy detecting more cases of metastatic lymphadenopathy than FNAB, although the difference in sensitivities was not statistically significant 4.
• However, for this specific case, since the lump is consistent with a lipoma and has been present for a year without any changes, a watchful waiting approach or a diagnostic biopsy may be considered to confirm the diagnosis.

Diagnostic Considerations

• The patient's history of lipomas and the characteristics of the lump suggest a benign lesion, but a definitive diagnosis can only be made with a biopsy.
• Imaging studies, such as MRI or ultrasound, may be used to further evaluate the lump and guide the biopsy procedure.
• The choice of biopsy procedure, such as FNAB or core needle biopsy, will depend on the size and location of the lump, as well as the patient's overall health and preferences.