A fibrolipomatous hamartoma of the nerve (also known as a neural fibrolipoma or lipomatosis of the nerve) is a benign neoplasm of nerves, resulting from anomalous growth of fibroadipose tissue of the nerve sheath.
Fibrolipomatous hamartoma may be related to hypertrophy of mature fat and fibroblasts in the epineurium.
A fibrolipomatous hamartoma of the nerve can involve the median (80%), ulnar and or radial nerves and or dorsum of the hand.
The WHO classification of tumors of soft tissue categorizes this entity under adipocytic tumors 3.
Macrodactyly of the involved limb or digit can be present in ~ 66% of all cases of fibrolipomatous hamartoma of the median nerve.
A characteristic hypoechoic coaxial cabling encased by an echogenic substratum may be seen 3.
MRI features are often pathognomonic and typically shows a coaxial cable-like appearance on axial images and a spaghetti-like appearance on coronal images 2,6.
- T1: the neural bundles were hyperintense to muscle and the surrounding substratum was isointense to muscle 3
- T2: fat components are high signal and fibrous components are low signal
History and etymology
It is thought to have been first reported by M L Mason in 1953 5.
Treatment and prognosis
The lesion is benign and the preferred management of the lesion is conservative.
- 1. Silverman TA, Enzinger FM. Fibrolipomatous hamartoma of nerve. A clinicopathologic analysis of 26 cases. Am. J. Surg. Pathol. 1985;9 (1): 7-14. - Pubmed citation
- 2. Jain TP, Srivastava DN, Mittal R et-al. Fibrolipomatous hamartoma of median nerve. Australas Radiol. 2007;51 Spec No. : B98-B100. doi:10.1111/j.1440-1673.2007.01790.x - Pubmed citation
- 3. Toms AP, Anastakis D, Bleakney RR et-al. Lipofibromatous hamartoma of the upper extremity: a review of the radiologic findings for 15 patients. AJR Am J Roentgenol. 2006;186 (3): 805-11. doi:10.2214/AJR.04.1717 - Pubmed citation
- 4. Murphey MD, Carroll JF, Flemming DJ et-al. From the archives of the AFIP: benign musculoskeletal lipomatous lesions. Radiographics. 24 (5): 1433-66. doi:10.1148/rg.245045120 - Pubmed citation
- 5. Mason ML. Presentation of cases. Proceedings of the American Society of Surgery of the Hand. J Bone Joint Surg Am. 1953 Jan 1;35A(1):273–275.
- 6. Chiang CL, Tsai MY, Chen CK. MRI diagnosis of fibrolipomatous hamartoma of the median nerve and associated macrodystrophia lipomatosa. J Chin Med Assoc. 2010;73 (9): 499-502. doi:10.1016/S1726-4901(10)70107-6 - Pubmed citation
- 7. Ha JF, Teh BM, Abeysuriya DT et-al. Fibrolipomatous hamartoma of the median nerve in the elbow: a case report. Ochsner J. 2012;12 (2): 152-4. Free text at pubmed - Pubmed citation