Case report 814: Fibrolipoma of the median nerve

Intraneural lipomas: institutional and literature review

BACKGROUND

Adipose lesions of nerve can be envisioned as a spectrum ranging from intraneural/extraneural lipomas to lipomatosis of nerve (LN). We have noticed that intraneural lipomas are not as a homogenous group as previously thought and demonstrate differences which have clinical implications. To better understand intraneural lipomas, we conducted a search of cases at our institution and published cases in the world's literature.

MATERIALS AND METHODS

Mayo Clinic's database was searched between years 1994-2018. Published cases were identified using PubMed and Google Scholar databases. Following terms were used: intraneural lipoma, lipoma and nerve, lipoma and neuropathy, lipofibroma and nerve, fibrolipoma and nerve and neural lipoma as well as lipofibroma and fibrolipoma alone. Cases that could be clearly identified as intraneural lipomas by the location of the lipoma within the epineurium were included for analysis. These cases were then sub-classified as encapsulated intraneural lipomas or hybrid intraneural lipomas (demonstrating features of both intraneural/extraneural lipomas and LN) based on their characteristics.

RESULTS

We identified 12 cases at our institution (8 encapsulated, 4 hybrid) and 24 published cases (21 encapsulated, 3 hybrid). The most commonly affected nerve was median both at our institution and in the published cases. Encapsulated cases were found to be relatively easy to resect. Hybrid cases demonstrated variable degree of interdigitating fat between the fascicles and were relatively difficult to resect.

CONCLUSION

Intraneural lipomas exist as two separate entities with distinct clinical implications. Although rare, this should be taken in account when planning surgery. Terminology should be clarified to prevent ambiguity and confusion.

Ultrasonographic diagnosis of lipofibromatous hamartoma of the median nerve

Lipofibromatous hamartoma (LFH) is an extremely rare benign tumor, which is characterized by an excessive infiltration of the epineurium and perineurium by fibroadipose tissues.A 27-year-old woman was diagnosed with left carpal tunnel syndrome (CTS) due to (LFH) of the median nerve. LFH was diagnosed by MRI and sonography; the characteristic ultrasonographic feature of LFH showed a good correlation with pathognomonic MRI findings. The median nerve was involved along its course in the forearm; however, the patient needed carpal tunnel release because of severe compression of the median nerve under the flexor retinaculum.Radiologic evaluation of patient with CTS to evaluate probable secondary CTS is recommended.

Lipofibromatous hamartoma of the median nerve: a comprehensive review and systematic approach to evaluation, diagnosis, and treatment

Many modalities exist for diagnosing and treating lipofibromatous hamartoma (LFH), with no clear consensus. This is the first comprehensive study to review the existing literature on LFH of the median nerve and to suggest a systematic approach to its diagnosis and treatment. An electronic and manual search was conducted on Medline, Embase, Google Scholar, Current Contents, and Science Citation Index for original and review articles in English or French, from 1946 to November 2012. After 2 levels of screening, 106 references containing case reports were retained. Data extraction included patient demographics, clinical information, diagnostic modalities, treatment, and follow-up. A total of 180 cases were reported in the literature. One third of patients had associated macrodactyly (32%). Gender distribution is equal in LFH with or without macrodactyly, with most patients (71%) presenting before age 30 years. The main presenting symptom is an enlargement (88%) over the volar forearm, wrist, or hand, with or without digital hypertrophy, followed by paresthesia (39%). A soft, mobile, nontender, nonfluctuant mass with variable degree of compressive median neuropathy is found on physical examination. Biopsy, which reveals abundant mature fat cells and fibrous connective tissue infiltrating between nerve fascicles and the space between the epineurium and the perineurium, is not necessary because the pathognomonic features of the mass on magnetic resonance imaging offer an accurate diagnosis. Treatment of nerve compression symptoms and macrodactyly should be addressed separately. Carpal tunnel release is the mainstay of treatment for neuropathy, and ray or digital amputation, wedge osteotomy, middle phalangectomy with arthroplasty, and epiphysiodesis are suggested options in the management of macrodactyly. Based on our review of the literature, we propose an algorithm for the diagnosis and treatment of LFH of the median nerve with or without macrodactyly.

Evidence-based guideline: neuromuscular ultrasound for the diagnosis of carpal tunnel syndrome

INTRODUCTION

The purpose of this study was to develop an evidence-based guideline for the use of neuromuscular ultrasound in the diagnosis of carpal tunnel syndrome (CTS).

METHODS

Two questions were asked: (1) What is the accuracy of median nerve cross-sectional area enlargement as measured with ultrasound for the diagnosis of CTS? (2) What added value, if any, does neuromuscular ultrasound provide over electrodiagnostic studies alone for the diagnosis of CTS? A systematic review was performed, and studies were classified according to American Academy of Neurology criteria for rating articles of diagnostic accuracy (question 1) and for screening articles (question 2).

RESULTS

Neuromuscular ultrasound measurement of median nerve cross-sectional area at the wrist is accurate and may be offered as a diagnostic test for CTS (Level A). Neuromuscular ultrasound probably adds value to electrodiagnostic studies when diagnosing CTS and should be considered in screening for structural abnormalities at the wrist in those with CTS (Level B).

MRI appearances of common benign soft-tissue tumours

Benign soft-tissue tumours are many times more common than their malignant counterparts, and magnetic resonance imaging (MRI) is the technique of choice for imaging the lesions. This review illustrates the MRI appearances of the most common benign soft-tissue tumours, based on consecutive referrals to our institution. The imaging signs that are useful for diagnosis are described.

Lipofibromatous Hamartoma of the Upper Extremity: A Review of the Radiologic Findings for 15 Patients

OBJECTIVE

The purpose of this study was to analyze the radiologic characteristics of lipofibromatous hamartomas affecting upper limb peripheral nerves.

CONCLUSION

Although there are pathognomonic features that characterize lipofibromatous hamartoma on MRI, the range of appearances is broad. Sonography appears to show equally characteristic features and may be a useful tool for assessing this condition.

Lipofibromatous hamartoma of the median nerve and its associated conditions

This study reports on ten cases of lipofibromatous hamartoma of the median nerve, with specific references to its associated conditions. Macrodactyly was the most common associated condition and was seen in 6 cases. Two cases had associated fatty tumours and another two had bony tumours. The literature was reviewed and a classification of the sites of involvement of the median nerve and its associated conditions is suggested.

From the archives of the AFIP. Imaging of musculoskeletal neurogenic tumors: radiologic-pathologic correlation

Numerous neurogenic tumors can affect the musculoskeletal system, including traumatic neuroma, Morton neuroma, neural fibrolipoma, nerve sheath ganglion, neurilemoma, neurofibroma, and malignant peripheral nerve sheath tumors (PNSTs). The diagnosis of neurogenic tumors can be suggested from their imaging appearances, including lesion shape and intrinsic imaging characteristics. It is also important to establish lesion location along a typical nerve distribution (eg, plantar digital nerve in Morton neuroma, median nerve in neural fibrolipoma, large nerve trunk in benign and malignant PNSTs). Traumatic and Morton neuromas are commonly related to an amputation stump or are located in the intermetatarsal space, respectively. Neural fibrolipomas show fat interspersed between nerve fascicles and are often associated with macrodactyly. Nerve sheath ganglion has a cystic appearance and commonly occurs about the knee. Radiologic characteristics of neurilemoma, neurofibroma, and malignant PNST at computed tomography (CT), ultrasonography, and magnetic resonance imaging include fusiform shape, identification of entering and exiting nerve, low attenuation at CT, target sign, fascicular sign, split-fat sign, and associated muscle atrophy. Although differentiation of neurilemoma from neurofibroma and of benign from malignant PNST is problematic, recognition of the radiologic appearances of neurogenic tumors often allows prospective diagnosis and improves clinical management of patients.

Fibrolipoma of the median nerve

Images

Intraneural lipofibroma of the median nerve

Intraneural lipofibroma of the median nerve is rare. We present three cases of this condition and discuss the surgical management. Open biopsy and carpal tunnel release are usually required.

Fibrolipomatous hamartoma: MR imaging findings

OBJECTIVE

To analyze the MR imaging features of fibrolipomatous hamartoma (FLH) of nerves.

DESIGN AND PATIENTS

MR imaging studies from six patients (three men and three women) were retrospectively reviewed by three musculoskeletal radiologists. In four patients, a biopsy of the nerve lesion was performed. In two patients, biopsy data were unavailable and the diagnosis was based on the clinical history combined with the MR imaging findings.

RESULTS AND CONCLUSION

MR imaging demonstrated fusiform nerve enlargement that was caused by fatty proliferation and thickening of nerve bundles. Nerve bundles appeared as serpentine tubular structures, hypointense on both T1- and T2-weighted images. The degree of fatty proliferation varied among patients. In addition, significant variation in the distribution of fat along the course of the nerves was noted. In three patients, FLH followed the branching pattern of the nerves, a characteristic pathologic finding. In two patients, intramuscular fat deposition (biceps and tibialis posterior muscles) was present. MR imaging findings of FLH are typical, allowing a confident diagnosis. The variation of fatty proliferation among patients and involved nerves as well as the tendency of the abnormalities to follow the branching pattern of the nerves is well demonstrated with MR imaging. FLH may present as an isolated nerve lesion, may be associated with intramuscular fat deposition, or may occur as a feature of macrodystrophia lipomatosa (MDL).

Pictorial review: imaging of peripheral nerve tumours

The ultrasound, computed tomography and magnetic resonance features of extracranial nerve tumours are reviewed. Characteristic locations and appearances help to define nerve tumours although the imaging findings of nerve and other soft tissue tumours overlap.