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Morphological Changes of the Median Nerve After Carpal Tunnel Release in a Median Nerve Lipofibromatous Hamartoma

Son, Eun-Seok, MD, PhD; Kim, Du Hwan, MD, PhD

American Journal of Physical Medicine & Rehabilitation: March 2019 - Volume 98 - Issue 3 - p e24–e26
doi: 10.1097/PHM.0000000000001004
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From the Department of Orthopedic Surgery, Dongsan Medical Center, School of Medicine, Keimyung University, Daegu, Korea (E-SS); and Department of Rehabilitation Medicine, Dongsan Medical Center, School of Medicine, Keimyung University, Daegu, Korea (DHK).

All correspondence should be addressed to: Du Hwan Kim, MD, PhD, Department of Rehabilitation Medicine, Dongsan Medical Center, School of Medicine, Keimyung University, 56 Dalseong-ro, Jung-gu, Daegu 41931, Korea.

E-SS and DHK did not receive any financial support or other benefits from commercial sources for the work reported on this manuscript, nor did any of the authors have any financial interests with regard to the work that may create a potential conflict of interest or the appearance of one. This work has not been presented, submitted, or published in any form or any language.

Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article.

A 41-yr-old woman presented with a tingling sensation in the right hand for 1 yr. On inspection, there was soft tissue swelling on the volar surface of the wrist and marked atrophic change of the thenar muscles. Ultrasonography (US) demonstrated a markedly increased cross-sectional area (0.455 cm2 at the maximal swollen point), which started from 2 cm proximal to the inlet of the carpal tunnel (Fig. 1). Magnetic resonance imaging of the wrist demonstrated fusiform enlargement of the median nerve with intermediate signal intensity on sagittal T2 sequences (Fig. 2). The lesion was suggestive of spaghetti string appearance on axial T2 sequences (Fig. 2). The patient underwent a carpal tunnel release. At surgery, prominent thickening of the median nerve was observed (Fig. 3). Considering the typical imaging findings and gross morphology, lipofibromatous hamartoma (LFH) was highly suspected and a biopsy was not performed. The patient's sensory symptoms completely resolved at the 6-mo follow-up. Follow-up US demonstrated morphological changes in which the shape changed from flattened to oval appearance without the change of cross-sectional area (0.454 cm2 at the maximal swollen point) and individual bundles of enlarged axons were apparent (Fig. 4).

FIGURE 1

FIGURE 1

FIGURE 2

FIGURE 2

FIGURE 3

FIGURE 3

FIGURE 4

FIGURE 4

Lipofibromatous hamartoma is a rare benign neoplasm consisting of fibroadipose tissue that affects peripheral nerves, most commonly the median nerve.1,2 Diagnosis of median nerve LFH is generally based magnetic resonance imaging or US.1,3 Spaghetti string appearance on images suggests that the nerve is enlarged (containing coaxial cable-like bundles of axons 2 to 3 mm in diameter encased in epineural fibrous tissue) and pathognomonic.3

This present case is unique in that follow-up US revealed a change in median nerve LFH morphology after carpal tunnel release. Surgical treatment of symptomatic median nerve LFH is the current standard of care; however, this approach remains highly controversial. Because of concerns over recurrence, more aggressive surgical treatment (e.g., invasive intraneural dissection, debulking surgery, early resection) were introduced as means to prevent repetitive surgeries.2 Nevertheless, most authors report carpal tunnel release alone as an initial treatment for median nerve LFH. In the present case, follow-up US demonstrated apparent morphologic changes of the median nerve after carpal tunnel release. Ultrasonography may be a useful tool in monitoring the tumor size and visualizing the extent of involvement.

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REFERENCES

1. Agarwal S, Haase SC: Lipofibromatous hamartoma of the median nerve. J Hand Surg Am 2013;38:392–7; quiz 7
2. Tahiri Y, Xu L, Kanevsky J, et al: Lipofibromatous hamartoma of the median nerve: a comprehensive review and systematic approach to evaluation, diagnosis, and treatment. J Hand Surg Am 2013;38:2055–67
3. Arora R, Arora AJ: Imaging features on sonography and MRI in a case of lipofibromatous hamartoma of the median nerve. Quant Imaging Med Surg 2014;4:207–9
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