Lipofibromatous Hamartoma of the Median Nerve in Association with or without Macrodactyly
Jyoti R KINI1, Hema KINI1, Aarathi RAU1, Jagannath KAMATH2, Anand KINI3
1Department of Pathology, Kasturba Medical College, Manipal University, Mangalore, KARNATAKA, INDIA
2Department of Orthopaedics, Kasturba Medical College, Manipal University, Mangalore, KARNATAKA, INDIA
3Department of Plastic Surgery, Kasturba Medical College, Manipal University, Mangalore, KARNATAKA, INDIA
Keywords: Carpal tunnel syndrome, Median nerve, Hamartoma
Lipofibromatous hamartoma is a rare tumour-like condition
involving the peripheral nerves, particularly the median nerve. It
commonly affects the volar aspect of the hands, wrists and forearms
of young adults. Most patients present either early with macrodactyly
or later with a forearm mass lesion or symptoms consistent with
compressive neuropathy of the involved nerve. The clinical and
histomorphological findings of five patients with lipofibromatous
hamartoma of the median nerve are analysed. The presentation,
pathological features and differential diagnosis of neural lipofibromas
are discussed along with a brief review of the literature. Of the five
cases of lipofibromatous hamartoma, all were seen to involve the
median nerve, occurring in four women and one man. Three of these
cases had associated macrodactyly which was congenital in two and
was seen from childhood in one. Microscopic examination showed
fibrofatty tissue surrounding and infiltrating along the epineurium
and perineurium. The nerve bundles were splayed apart by the
infiltrating adipose tissue. Neural fibrolipomatous hamartoma is a
benign condition. Most respond to conservative management with
surgical exploration, biopsy and carpal tunnel release to decompress
the nerve. Correct diagnosis of this uncommon lesion is important
as surgical excision of the lesion may lead to loss of neurological
Lipofibromatous Hamartoma (LFH) of the nerve is a rare
tumour-like condition involving the peripheral nerves, most
commonly in the upper extremity with a predilection for
the median nerve. It is almost always described in children
and young adults. The lesion is sometimes associated with
macrodactyly and lipomatous macrodystrophy of muscles
and subcutaneous fat in the region supplied by the nerve.
The characteristic enlargement of the affected nerve trunk
is caused by the proliferation of the epineural adipose tissue
associated with perineural fibrosis.
Five cases of LFH of the median nerve sent for
histopathological examination from July 1991 to June 2011
were retrieved from the departmental records maintained
in our institute. The H&E stained paraffin sections were
reviewed for the histomorphological features.
Case 1: A 30-year-old woman presented with a fiveyear
history of swelling in the left hand and wrist. On
examination she had features of carpal tunnel syndrome.
On surgical exploration the carpal tunnel was tight and
showed thickened median nerve from eight centimeters above the wrist joint. The carpal tunnel was decompressed
and the thickened nerve sheath relieved. A biopsy was sent
Case 2: An 18-year-old girl presented with complaints of
insidious onset of pain and swelling in the right hand of one
month duration associated with macrodactyly of ring finger
which was present since childhood. On examination, there
was diffuse swelling in the ventral aspect of the forearm and
hand along with enlargement of the ring finger (Figure 1).
There was no neurological deficit. On exploration, the mass
was seen to arise from the median nerve (Figure 2).
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|Figure 1: An 18-year-old girl presented with diffuse swelling in
the ventral aspect of the hand and enlargement of the ring finger.
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|Figure 2: Intraoperatively a mass was seen to arise from the
Case 3: A 28-year-old woman came to the orthopedic
outpatient department with an insidious history of swelling
in the right hand and forearm associated with macrodactyly
of thumb and index finger since birth. On examination
she had diffuse swelling in the volar aspect of the right
hand, macrodactyly of thumb and index finger. There was
ventral angulation and deformity of the index finger. The movements of the wrist joint, the index finger and thumb
were slightly limited and mildly painful when forced.
Surgical exploration with decompression of the median
nerve and excision of the mass involving the digital nerve
of the index finger was done. The right index finger was
Case 4: A 16-year-old girl presented with a history of
progressively increasing swelling in the right hand and
forearm associated with macrodactyly of thumb since
birth. On examination, the right hand showed a diffuse
mass in the ventral aspect of the forearm, wrist and thenar
region along with enlargement of the thumb. There was no
neurological deficit. Fibrofatty tissues were dissected and
removed from the nerve. The result of surgical debulking
was satisfactory. Post-operatively there was no change in
function or recurrence of the mass.
Case 5: A 30-year-old man presented with complaints of
swelling in the right forearm of six years duration associated
with intermittent pain. On examination, there was diffuse
swelling in the ventral aspect of the forearm. There was no
neurological deficit. On exploration, an oval bright yellow
mass was seen to arise from the median nerve. The fibrofatty
sheath was decompressed and the mass was excised.
The case histories and clinical findings of the five patients
are summarized in Table I.
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|Table I: The clinical details of the five patients are summarized below
Histopathological findings: The H&E stained slides of
all the lesions showed fibrofatty tissue surrounding and
infiltrating along the epineurium and perineurium (Figure
3). The nerve bundles were splayed apart by the infiltrating
mature adipose tissue (Figure 4). Perineural fibrosis was
identified in four cases and focal myxoid change was seen in one case. Immunohistochemical staining with S
100 protein in one of the case showed strong positivity of
the nerve fibres (Figure 5). All lesions were diagnosed as
lipofibromatous hamartoma of the median nerve.
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|Figure 3: Section shows fibrofatty tissue surrounding and
infiltrating along the epineurium and perineurium. (H&E; x100).
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|Figure 4: Section shows nerve bundles splayed apart by the
infiltrating mature adipose tissue. (H&E; x100).
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|Figure 5: Section shows cross section of nerve bundle with
perineural proliferation and strong immunoreactivity of the
Schwann cells for S 100. (S100; x200).
Lipofibromatous hamartoma of the nerve is an uncommon
neural non-neoplastic lesion demonstrating gross enlargement
of a nerve caused by epineural and perineural proliferation of fibrofatty tissue1-5
. Less than 100 cases of
LFH affecting the median nerve have been documented, of
which about one-fourth were associated with true macrodactyly
in the territory of the nerve distribution, predominantly
. We present five more cases of lipofibromatous
hamartoma of the median nerve occurring in
four women and one man. Three of these cases had associated
Numerous synonyms have been used for describing
this condition, the most common ones being neural
fibrolipoma, neural fibrolipomatosis, neural lipofibroma,
neural lipomatous hamartoma, neural fibrolipomatous
hamartoma, fatty infiltration of nerve and fibrofatty
proliferation of peripheral nerve3-9.
This uncommon benign slow growing lesion with an
indolent course was first reported by Mason in 19536. This was followed by two cases of diffuse fibrofatty
overgrowth involving the adipose tissue of the median
nerve published by Mikhail in 19647. One was a case of
macrodystrophia lipomatosa of the thumb and index finger
with a marked fibrofatty infiltration of the median nerve
and its digital branches to the thumb and index finger. The
other was termed fibrolipoma of the median nerve trunk.
Yeoman reported three patients with fatty infiltration of the
median nerve and stated that the intimate association of the
fibrofatty tissue within the nerve precluded enucleation of
the swelling8. Johnson and Bonfiglio in 1969 reviewed
the literature and put up a case of their own with detailed
histological account of the lesion and coined the term
lipofibromatous hamartoma of nerve, which aptly fits the
In our series there was 100% involvement of the median
nerve, four of the five cases were in women, three had
macrodactyly, and the age range at presentation varied
from 16 to 30 years. Approximately, 80% of these lesions
originate in the distribution of the median nerve with a
predilection for the carpel tunnel1-12. Other reported
sites of involvement include the ulnar nerve2,11,13-15,
radial nerve16, nerves of the foot3, brachial plexus,
and cranial nerves17. Patients commonly present within
the first three decades of life with few reports in children
that are considered congenital by some authors8,9,14.
The female: male ratio is approximately 2:114. The
most common presentation of LFH is a mass or swelling
on the volar aspect of the wrist or distal forearm. Neural
fibrolipomatous hamartoma can be asymptomatic or
accompanied by pain; there may be local motor or sensory
symptoms, and late compression neuropathy. Macrodactyly
is seen in 25 to 60 percent of patients with LFH and is most
often congenital2,3,14. Macrodactyly was present in three
of our cases, was congenital in two and seen from childhood
in one. Two of our patients presented with tingling and
paraesthesia along the distribution of the median nerve
in the hand predominantly affecting the palmar aspect of
thumb and index finger.
Neural fibrolipoma is an orange- yellow, fusiform, sausage
like or ropelike enlargement of the nerve3,4,10,11,18. The
sheath of the nerve is shiny, intact and non-adherent, but
thick, firm and non-resilient as in case 1 in this study. The
nerves may be markedly increased in length and diameter
in the involved area4. Preoperative diagnosis is made
by Magnetic Resonance Imaging (MRI) where the lesion
produces the characteristic feature known as the cable sign5. The thickened nerve bundles surrounded by uniformly
distributed fat appear as serpentine, low intensity structures
encircled by high intensity signal giving rise to the cable
like appearance in the axial plane and a spaghetti- like
or strands of hair appearance in the coronal plane1.
Electromyography and nerve conduction studies can show
prolonged latency of sensory or motor innervations and
fibrillations in distal muscles to confirm a compressive
myopathy4,14. None of our patients had undergone MRI
Morphology remains the mainstay of diagnosis and
immunohistochemistry does not aid in the diagnosis of
these lesions. The Schwann cells typically are strongly
positive for S 100 protein and myelin in the nerve fibres
show intense positivity for basic myelin protein. The
perineural cells stain positive for epithelial membrane
Lipofibromatous Hamartoma is considered to be a
hamartoma because of the overgrowth of the normal
connective tissue components: fat and fibrous tissue15,17.
On microscopic examination, a fibrofatty expansion of the
epineural space is seen with splaying of the nerve bundles.
Perineural fibrosis and endoneural fibrosis may be seen.
Occasionally, in long standing lesions, metaplastic bone is
found in the fibrofatty tissue1,2. The differential diagnosis
of LFH on histopathology includes neural lipomas, diffuse
lipomatosis, neuromas and neurofibromas. Lipoma of the
nerves is an encapsulated fatty proliferation encloses the
nerve sheaths2,3. Histology clinches the diagnosis as there
is no characteristic scattering of individual nerve fascicles
within the fatty mass in these tumours2,3,17. In diffuse
lipomatosis there is primary involvement of muscle and
subcutis with the nerves being secondarily involved. Other
differential diagnoses such as neuromas and neurofibromas
can be ruled out by the absence of proliferation of the
Neural fibrolipomatous hamartoma is a benign condition.
Treatment of LFH is directed towards management of the
digital or soft tissue involvement and management of the
enlarged nerve. The surgical management of this condition
is controversial and most often involves conservative
management with surgical exploration, biopsy and carpal
tunnel release to decompress the nerve. The ideal plan is
to release the fascia of the forearm, carpal tunnel, palm, or
digit, as indicated by the location of the lesion1,3,10. The
lesion can be debulked extensively to improve the functional
status. Extensive microsurgical intraneural dissection can
lead to significant ischemic complications12,14. Nerve
fasciotomy with simple excision of fatty tissue and sparing of
the nerve is the treatment of choice. Complete excision of a
lipofibromatous hamartoma of the median nerve can result
in disastrous loss of neurological function. Patients with
macrodactyly or advanced disease may require debulking
and reconstructive procedures aimed at improving hand
function4. Awareness of this condition is crucial in order
to avoid misdiagnosis on biopsy, which may result in a
more drastic surgery.
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