Proteus syndrome with sciatic nerve fibrolipomatous hamartoma: an uncommon finding in a rare disease: report of two cases with literature review

Proteus syndrome is an extremely rare condition, characterized by progressive asymmetric overgrowth of multiple body tissues. Here we present two cases of Proteus syndrome demonstrating typical clinical and radiological features of Proteus syndrome, in addition to an uncommon fibrolipomatous hamartoma of the sciatic nerve. The first case is a five-year-old girl who presented with seizures. The patient showed facial dysmorphic features, left head enlargement, kyphoscoliosis, asymmetric overgrowth of the right lower limb, right foot drop, and cribriform connective tissue nevi on the right palm and the right sole. Radiological examinations demonstrated left calvarial hyperostosis, dysplasia of the left cerebral hemisphere, dysregulation of the subcutaneous adipose fat of the body, kyphoscoliosis, and lipoma of the filum terminale. CT of both thighs showed asymmetric soft tissue overgrowth of the right thigh, associated with diffuse enlargement and fatty infiltration of the right sciatic nerve starting from the upper thigh, down to its bifurcation into the tibial and common peroneal nerves. The second case is an eighteen-year-old girl who presented with left conductive deafness. The patient showed facial dysmorphic features, right head enlargement, asymmetric overgrowth of the right upper limb, kyphoscoliosis, left foot drop, and cribriform connective tissue nevi on the nose and the left foot. Radiological examinations demonstrated right calvarial hyperostosis, left external auditory canal hyperostosis and stenosis, and kyphoscoliosis. CT and MRI of both thighs showed diffuse enlargement of the left sciatic nerve starting from the upper thigh down to the mid-thigh and showing inter fascicular adipose tissue proliferation, giving the typical features of nerve lipomatosis.

Fibrolipomatous Hamartoma Arising from the Median Nerve—A Case Report

Fibrolipomatous hamartoma is a rare nonhereditary, congenital condition characterized by benign hyperplasia of fibroadipose tissue around nerve bundles. The median nerve is commonly affected. Underlying pathological process is mature adipose and fibrous tissue infiltrating the epineural and perineural compartments giving typical “pseudo-onion bulb” appearance on histology and “coaxial cable” appearance on magnetic resonance imaging (MRI). This case of fibrolipomatous hamartoma well illustrates its characteristic clinical, radiological, and histopathological features. Patient is a teenage female presented with painless gradually enlarging mobile lump in the central left palm. Ultrasound scan revealed a hyperechoic subcutaneous lesion, with intervening fine hypoechoic cable like structures following the course of median nerve which was thickened. Computed tomography (CT) confirmed thickened left median nerve with radiating isodense fascicles surrounded by fatty areas. There were no calcifications. MRI showed classic “coaxial cable” like T1, T2 isointense fascicles continuous with the median nerve surrounded by a fusiform lesion demonstrating fat signals on spin-echo sequences which dropped on fat-suppressed gradient echo sequences. Diagnosis of fibrolipomatous hamartoma arising from left median nerve was made, based on typical imaging findings. Biopsy confirmed fibrolipomatous hamartoma. Diagnosis can be made confidently on imaging alone especially with MRI, without the need of biopsy. Both CT and MRI demonstrate fatty mass encasing the thickened nerve fibers. On MRI, characteristic appearance is seen as T1 and T2 low intense tubular thickened neural bundles surrounded by high signal fatty tissue.

Carpal Tunnel Syndrome Caused by A Fibrolipomatous Hamartoma of the Median Nerve

Fibrolipomatous hamartoma (FLH) of the nerve (also known as perineural lipoma, neural fibrolipoma, or lipomatosis of the nerve) is a well-known, rare benign lesion that can affect any peripheral nerve, resulting in significant enlargement of the involved nerve with fibrofatty infiltration. Although it is most commonly involving the median nerve, other peripheral nerves can be also involved. Being familiar with the pathognomonic characteristics on different imaging modalities and the association of this entity with macrodactyly help reach the diagnosis, avoid putting the patient at risk of an invasive procedure, and can guide management. We present to you a rare case of a FLH of the median nerve that was diagnosed on MRI of an adult female who presented with carpal tunnel syndrome (CTS) and progressive swelling of the right hand and wrist.

Fibrolipomatous Hamartoma of the Median Nerve of the Hand: A Case Report and Literature Review

Introduction: Fibrolipomatous Hamartoma (FLH) is a rare tumor-like disease, mainly occurs in benign tumors of the peripheral nerves of the upper limbs, which characterized by the overgrowth of neuronal fat and fibrous tissue.Case presentation: A patient had numbness of fingers in the left hand for more than 5 years. Three years ago, the superficial sensation at the metacarpophalangeal joint of the hypothenar of the left hand was weakened. Two years later, the distal ulnar side of the index finger and the distal radial side of the middle finger were secondary to weakened superficial sensation and megalodactyly symptoms of the middle finger and index finger of the left hand were developed. Physical examination showed a mass on the left palm side. MRI showed an abnormal subcutaneous fusiform signal at the palmar side of the left wrist: T1W1 isointensity, T2W1 inhomogeneous slightly hyperintense signal. The clinical features, radiologic presentations, treatment choice, and pathologic characteristic were illustrated. During the operation, the appearance of the nerve was hypertrophic and variant, without obvious masses, the proliferated fibrous tissues were showed a fusiform change, and the nerve fibers were degenerated and atrophied. Immunohistochemical results showed S-100 (+), NSE (focus +), EMA (portion +), GFAP (-), ERG (blood vessel +), SMA (blood vessel +), Ki-67 (1%+), NF (small region +). The patient's finger numbness symptom improved obviously and the condition was stable when paying a return visit 3 months after the operation. Conclusions：The clinical symptoms of FLH of median nerve mainly include gradually enlarged painless mass, macrodactyly, pain, numbness, paresthesia and carpal tunnel syndrome. The diagnosis mainly depends on ultrasonic examination and MRI. The pathological sections of FLH sometimes show perineurioma-like changes, which need to be identified by clinical and MRI features. The treatment methods include prophylactic carpal tunnel release (CTR) and nerve transplantation after the whole nerve resection. CTR, has been proven to be helpful for many patients suffering from carpal tunnel symptoms and can relieve most of the symptoms, is the main method. However, the pathogeny needs to be further explored.

FIBRO-LIPOMATOUS HAMARTOMA.

Fibro-lipomatous hamartomas are non-malignant tumors that are commonly seen in infants and rarely affect young adults and children.[1] Neural fibro-lipoma, lipo-fibromatous hamartoma, peri-neural lipoma and intra-neural lipoma are the other terms used for fibrolipomatous hamartoma. Among all, the median nerve is by far the most commonly affected(80% of cases) and less commonly the ulnar and radial nerves, and brachial plexus. [2] Although median nerve is the commonly affected nerve, lesions are also found in the radial, sciatic, plantar and ulnar nerves. Further,the median nerve is most commonly involved at the level of hand and wrist.[3]