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Fibrolipoma of the median nerve
Joint Bone Spine 74 (2007) 98e99 http://france.elsevier.com/direct/BONSOI/
Case report
Fibrolipoma of the median nerve Kais Nouira a,*, Hend Belhiba a, Sofie`ne Baccar a, Anissa Miaaoui a, Monia Ben Messaoud a, Ime`ne Turki a, Ilhem Cheour b, Emna Menif a a
Medical Imaging Department, La Rabta Hospital, 5 Rue Ibn Messaoud, El Menzeh 6, 2091 Tunis, Tunisia b Rheumatology Department, La Rabta Hospital, Tunis, Tunisia Received 23 June 2005; accepted 17 February 2006 Available online 13 November 2006
Abstract Neural fibrolipoma or fibrolipomatous hamartoma is an uncommon benign tumor that usually arises in the median nerve. Fibrofatty tissue proliferates around the nerve and infiltrates the epineurium and perineurium. We report a case of fibrolipomatous hamartoma of the left median nerve in an 18-year-old woman. Our objective was to describe the pathognomonic magnetic resonance imaging features, whose presence obviates the need for a diagnostic biopsy. Ó 2006 Elsevier Masson SAS. All rights reserved. Keywords: Ultrasonography; Fibrolipomatous hamartoma; Median nerve
1. Introduction Neural fibrolipoma or fibrolipomatous hamartoma is a rare benign tumor composed of fibrofatty tissue surrounding a nerve and infiltrating the epineurium and perineurium [1]. Most cases are diagnosed in childhood or early adulthood. 2. Case report An 18-year-old woman presented with a soft lump in the palm of the left hand and volar aspect of the left thumb. The lump had been present since childhood. She had no other symptoms. The neurological evaluation was normal, Phalen’s maneuver was negative, and Tinel’s sign was absent. Ultrasonography showed an elongated hyperechoic mass containing co-axial hypoechoic bands. The mass measured 10 cm 2 cm 1.5 cm. It originated in the distal third of the forearm, prolonging the median nerve and passing through the carpal tunnel to the thenar compartment and volar aspect of the thumb. Magnetic resonance imaging (MRI) showed * Corresponding author. Tel.: þ216 98 33 42 93; fax: þ216 71 57 87 74. E-mail address: [email protected] (K. Nouira).
a signal of fat intensity without postgadolinium enhancement. The mass prolonged the median nerve in the distal third of the left forearm, dissociating the nerve fibers, which were seen as low-intensity signal on T1- and T2-weighted images. The mass passed through the carpal tunnel to the thenar compartment and volar aspect of the thumb (Figs. 1 and 2). These features were consistent with fibrolipomatous hamartoma of the left median nerve. Given the absence of symptoms and of major deformity, a wait-and-see approach was adopted. 3. Discussion Fibrolipomatous hamartoma, also known as neural fibrolipoma, perineural lipoma, or intraneural lipoma, is an extremely uncommon benign tumor. The first description was published in 1953 [1]. The median nerve and its branches are the main sites of involvement, followed by the radial nerve, ulnar nerve, nerves at the dorsal aspect of the foot, brachial plexus, and cranial nerves [2,3]. Adults younger than 30 years of age are selectively affected [1]. Although the etiopathogenesis of fibrolipomatous hamartoma remains unknown, a congenital abnormality affecting the growth of fibrofatty tissue in the nerve sheath is the most likely mechanism. Fibrofatty tissue infiltrates the endoneurium, perineurium, and epineurium, causing enlargement of the nerve.
1297-319X/$ - see front matter Ó 2006 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.jbspin.2006.02.012
K. Nouira et al. / Joint Bone Spine 74 (2007) 98e99
99
Fig. 2. Magnetic resonance imaging, T1-weighted sequence, axial section through the metacarpals of the left hand: fatty tissue that infiltrates and enlarges the median nerve, surrounding the nerve fibers (arrowheads).
Fig. 1. Magnetic resonance imaging, T1-weighted sequence, sagittal section centered on the left hand: high-signal mass containing low-signal bands and traveling through the carpal tunnel.
A soft, lump in the palm of the hand, wrist, and/or forearm growing slowly since childhood is the most common presentation. Although pain, paresthesia, or carpal tunnel syndrome may be present, many patients have no symptoms. About twothirds of patients exhibit macrodactyly, which predominantly affects the phalanges and is related to periosteal and endosteal bone formation [2,4,5]. The combination of fibrolipomatous hamartoma and macrodactyly, known as lipomatous macrodystrophy, should prompt a search for a hemangioma, a lymphangioma, an arteriovenous malformation, or neurofibromatosis [4e6]. Less common findings in patients with fibrolipomatous hamartoma include ectopic soft tissue calcifications, bony excrescences, subcutaneous lipomas, fatty infiltration of the muscles, and vascular tumors in Ref. [6]. Bony metaplasia of the tumor may occur (ossifying fibrolipomatous hamartoma) and should be distinguished from macrodactyly. Standard radiographs may be normal or may show soft tissue thickening related to the proliferation of fibrofatty tissue [7]. In digits with macrodactyly, hypertrophy of the bone is seen as widening and lengthening of the phalanges with joint space narrowing and, in some patients, osteophytes [4]. Ultrasonography shows a hyperechoic mass containing co-axial hypoechoic bands [8], with no vascularization by color Doppler. The mass is continuous with the nerve and develops along the nerve trajectory. MRI is the key diagnostic investigation. The mass generates a fat-intensity signal (high signal on T1- and T2-weighted images with saturation on fat-suppression images). Serpiginous bands of low signal on T1and T2-weighted images represent enlarged nerve fascicles and fibrous tissue. The result is a pathognomonic co-axial cable-like
appearance on axial sections and spaghetti-like appearance on coronal sections [1,9]. In our patient, passage of the tumor through the carpal tunnel produced a bow-tie image. Surgical biopsy is unnecessary in patients who exhibit pathognomonic MRI features [9]. The treatment of fibrolipomatous hamartoma is highly controversial. The tumor infiltrates the nerve, so that tumor excision can be achieved only at the cost of sacrificing the nerve. But nerve resection is usually contraindicated, so complete tumor excision is not feasible [10]. 4. Conclusion The MRI appearance of fibrolipomatous hamartoma is pathognomonic. Histological confirmation is not always required, particularly as complete tumor excision can be achieved only at the cost of sacrificing the nerve. References [1] Van Breuseghem I, Sciot R, Pans S, Geusens E, Brys P, De Wever I. Fibrolipomatous hamartoma in the foot: atypical MR imaging findings. Skeletal Radiol 2003;32:651e5. [2] Ly JQ, Bui-Mansfield LT, SanDiego JW, Beaman NA, Ficke JR. Neural fibrolipoma of the foot. J Comput Assist Tomogr 2003;27:639e40. [3] Silverman TA, Enzinger FM. Fibrolipomatous hamartoma of nerve. A clinicopathologic analysis of 26 cases. Am J Surg Pathol 1985;9:7e14. [4] Sone M, Ehara S, Tamakawa Y. Macrodystrophia lipomatosa: CT and MR findings. Radiat Med 2000;18:129e32. [5] Gupta SK, Sharma OP, Sharma SV, Sood B, Gupta S. Macrodystrophia lipomatosa: radiographic observations. Br J Radiol 1992;65:769e73. [6] Al-Qattan MM. Lipofibromatous hamartoma of the median nerve and its associated conditions. J Hand Surg 2001;26:368e72. [7] Murphey MD, Smith WS, Smith SE, Kransdorf MJ, Temple HT. From the archives of the AFIP. Imaging of musculoskeletal neurogenic tumors: radiologic-pathologic correlation. Radiographics 1999;19:1253e80. [8] Stuart RM, Koh ESC, Breidahl WH. Sonography of peripheral nerve pathology. AJR 2004;182:123e9. [9] Marom EM, Helms CA. Fibrolipomatous hamartoma: pathognomonic on MR imaging. Skeletal Radiol 1999;28:260e4. [10] Chick G, Alnot JY, Silbermann-Hoffman O. Tumeurs be´nignes isole´es des nerfs pe´riphe´riques. Rev Chir Orthop 2000;86:825e34.
Case report
Fibrolipoma of the median nerve Kais Nouira a,*, Hend Belhiba a, Sofie`ne Baccar a, Anissa Miaaoui a, Monia Ben Messaoud a, Ime`ne Turki a, Ilhem Cheour b, Emna Menif a a
Medical Imaging Department, La Rabta Hospital, 5 Rue Ibn Messaoud, El Menzeh 6, 2091 Tunis, Tunisia b Rheumatology Department, La Rabta Hospital, Tunis, Tunisia Received 23 June 2005; accepted 17 February 2006 Available online 13 November 2006
Abstract Neural fibrolipoma or fibrolipomatous hamartoma is an uncommon benign tumor that usually arises in the median nerve. Fibrofatty tissue proliferates around the nerve and infiltrates the epineurium and perineurium. We report a case of fibrolipomatous hamartoma of the left median nerve in an 18-year-old woman. Our objective was to describe the pathognomonic magnetic resonance imaging features, whose presence obviates the need for a diagnostic biopsy. Ó 2006 Elsevier Masson SAS. All rights reserved. Keywords: Ultrasonography; Fibrolipomatous hamartoma; Median nerve
1. Introduction Neural fibrolipoma or fibrolipomatous hamartoma is a rare benign tumor composed of fibrofatty tissue surrounding a nerve and infiltrating the epineurium and perineurium [1]. Most cases are diagnosed in childhood or early adulthood. 2. Case report An 18-year-old woman presented with a soft lump in the palm of the left hand and volar aspect of the left thumb. The lump had been present since childhood. She had no other symptoms. The neurological evaluation was normal, Phalen’s maneuver was negative, and Tinel’s sign was absent. Ultrasonography showed an elongated hyperechoic mass containing co-axial hypoechoic bands. The mass measured 10 cm 2 cm 1.5 cm. It originated in the distal third of the forearm, prolonging the median nerve and passing through the carpal tunnel to the thenar compartment and volar aspect of the thumb. Magnetic resonance imaging (MRI) showed * Corresponding author. Tel.: þ216 98 33 42 93; fax: þ216 71 57 87 74. E-mail address: [email protected] (K. Nouira).
a signal of fat intensity without postgadolinium enhancement. The mass prolonged the median nerve in the distal third of the left forearm, dissociating the nerve fibers, which were seen as low-intensity signal on T1- and T2-weighted images. The mass passed through the carpal tunnel to the thenar compartment and volar aspect of the thumb (Figs. 1 and 2). These features were consistent with fibrolipomatous hamartoma of the left median nerve. Given the absence of symptoms and of major deformity, a wait-and-see approach was adopted. 3. Discussion Fibrolipomatous hamartoma, also known as neural fibrolipoma, perineural lipoma, or intraneural lipoma, is an extremely uncommon benign tumor. The first description was published in 1953 [1]. The median nerve and its branches are the main sites of involvement, followed by the radial nerve, ulnar nerve, nerves at the dorsal aspect of the foot, brachial plexus, and cranial nerves [2,3]. Adults younger than 30 years of age are selectively affected [1]. Although the etiopathogenesis of fibrolipomatous hamartoma remains unknown, a congenital abnormality affecting the growth of fibrofatty tissue in the nerve sheath is the most likely mechanism. Fibrofatty tissue infiltrates the endoneurium, perineurium, and epineurium, causing enlargement of the nerve.
1297-319X/$ - see front matter Ó 2006 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.jbspin.2006.02.012
K. Nouira et al. / Joint Bone Spine 74 (2007) 98e99
99
Fig. 2. Magnetic resonance imaging, T1-weighted sequence, axial section through the metacarpals of the left hand: fatty tissue that infiltrates and enlarges the median nerve, surrounding the nerve fibers (arrowheads).
Fig. 1. Magnetic resonance imaging, T1-weighted sequence, sagittal section centered on the left hand: high-signal mass containing low-signal bands and traveling through the carpal tunnel.
A soft, lump in the palm of the hand, wrist, and/or forearm growing slowly since childhood is the most common presentation. Although pain, paresthesia, or carpal tunnel syndrome may be present, many patients have no symptoms. About twothirds of patients exhibit macrodactyly, which predominantly affects the phalanges and is related to periosteal and endosteal bone formation [2,4,5]. The combination of fibrolipomatous hamartoma and macrodactyly, known as lipomatous macrodystrophy, should prompt a search for a hemangioma, a lymphangioma, an arteriovenous malformation, or neurofibromatosis [4e6]. Less common findings in patients with fibrolipomatous hamartoma include ectopic soft tissue calcifications, bony excrescences, subcutaneous lipomas, fatty infiltration of the muscles, and vascular tumors in Ref. [6]. Bony metaplasia of the tumor may occur (ossifying fibrolipomatous hamartoma) and should be distinguished from macrodactyly. Standard radiographs may be normal or may show soft tissue thickening related to the proliferation of fibrofatty tissue [7]. In digits with macrodactyly, hypertrophy of the bone is seen as widening and lengthening of the phalanges with joint space narrowing and, in some patients, osteophytes [4]. Ultrasonography shows a hyperechoic mass containing co-axial hypoechoic bands [8], with no vascularization by color Doppler. The mass is continuous with the nerve and develops along the nerve trajectory. MRI is the key diagnostic investigation. The mass generates a fat-intensity signal (high signal on T1- and T2-weighted images with saturation on fat-suppression images). Serpiginous bands of low signal on T1and T2-weighted images represent enlarged nerve fascicles and fibrous tissue. The result is a pathognomonic co-axial cable-like
appearance on axial sections and spaghetti-like appearance on coronal sections [1,9]. In our patient, passage of the tumor through the carpal tunnel produced a bow-tie image. Surgical biopsy is unnecessary in patients who exhibit pathognomonic MRI features [9]. The treatment of fibrolipomatous hamartoma is highly controversial. The tumor infiltrates the nerve, so that tumor excision can be achieved only at the cost of sacrificing the nerve. But nerve resection is usually contraindicated, so complete tumor excision is not feasible [10]. 4. Conclusion The MRI appearance of fibrolipomatous hamartoma is pathognomonic. Histological confirmation is not always required, particularly as complete tumor excision can be achieved only at the cost of sacrificing the nerve. References [1] Van Breuseghem I, Sciot R, Pans S, Geusens E, Brys P, De Wever I. Fibrolipomatous hamartoma in the foot: atypical MR imaging findings. Skeletal Radiol 2003;32:651e5. [2] Ly JQ, Bui-Mansfield LT, SanDiego JW, Beaman NA, Ficke JR. Neural fibrolipoma of the foot. J Comput Assist Tomogr 2003;27:639e40. [3] Silverman TA, Enzinger FM. Fibrolipomatous hamartoma of nerve. A clinicopathologic analysis of 26 cases. Am J Surg Pathol 1985;9:7e14. [4] Sone M, Ehara S, Tamakawa Y. Macrodystrophia lipomatosa: CT and MR findings. Radiat Med 2000;18:129e32. [5] Gupta SK, Sharma OP, Sharma SV, Sood B, Gupta S. Macrodystrophia lipomatosa: radiographic observations. Br J Radiol 1992;65:769e73. [6] Al-Qattan MM. Lipofibromatous hamartoma of the median nerve and its associated conditions. J Hand Surg 2001;26:368e72. [7] Murphey MD, Smith WS, Smith SE, Kransdorf MJ, Temple HT. From the archives of the AFIP. Imaging of musculoskeletal neurogenic tumors: radiologic-pathologic correlation. Radiographics 1999;19:1253e80. [8] Stuart RM, Koh ESC, Breidahl WH. Sonography of peripheral nerve pathology. AJR 2004;182:123e9. [9] Marom EM, Helms CA. Fibrolipomatous hamartoma: pathognomonic on MR imaging. Skeletal Radiol 1999;28:260e4. [10] Chick G, Alnot JY, Silbermann-Hoffman O. Tumeurs be´nignes isole´es des nerfs pe´riphe´riques. Rev Chir Orthop 2000;86:825e34.