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tumor in the hypothenar space and Guyon’s canal [Figure 3]. authors postulated that the lipoma originated from the
The distal sensory branches of the ulnar nerve were firmly nerve itself and termed it an “intra neural lipoma”. Our
adherent to the tumor and were splayed by it. It appeared case was similar in presentation. The lipoma was present
as if the branches were embedded in the tumor capsule. between the superficial and deep branches of the ulnar
There was inadvertent injury to the ulnar digital nerve to nerve. The superficial sensory branches were splayed by
the little finger, which was repaired with 8–0 nylon. the tumor and appeared to be embedded in the capsule.
Hence, an intraneural origin cannot be ruled out.
Postoperative recovery was uneventful. The histopathological
examination showed mature fat cells, suggestive of lipoma. The possibility of nerve injury should always be discussed
At 6-month follow-up, the patient was doing well with with the patient preoperatively. Extreme caution should
normal sensation on the ring and little fingers.

DISCUSSION

Lipoma in Guyon’s canal is rare, with only 13 cases
reported, including the present case [Table 1].
[9]
Except for the case of an 8 years old, all others were
reported in adults, ranging from 36 to 74 years old,
with a mean age of 52.2 years. There were 7 males and
6 females. Nine of the 13 cases occurred on the right
side. The tumor size varied from 1.5 cm × 1 cm (area)
to 6.5 cm × 4 cm × 2.5 cm (volume), with this largest
lesion seen in the present case. Six patients had only
sensory involvement, 2 had only motor symptoms, and
4 patients had a combined neuropathy. One patient
had no neuropathy and was the only pediatric patient Figure 1: Diffuse swelling in the hypothenar area
in the series. This was attributed to unique anatomical
and physiological differences for Guyon’s canal and the
attending nerves. MRI was taken in 7 cases. It gave
[9]
accurate diagnosis in 5 patients, while, in 2 cases, the
findings were suggestive of ganglion. [6,13] Surgical removal
alleviated symptoms in all patients.

Shea and McClain have classified lesions of Guyon’s canal
into three types: type I – proximal lesions having both
sensory and motor involvement (30%), type II – lesions
causing weakness of the intrinsic muscles (52%)
and type III – distal lesions causing only sensory
abnormalities (18%). Recently Wu et al. have suggested
[14]
[15]
a classification into five types. Type I is a mixed a b
motor and sensory neuropathy with the lesion at the Figure 2: Magnetic resonance imaging finding of hyper-intense lesion in
proximal end of Guyon’s canal. Type II is a pure sensory T1 (a) with short T1 inversion recovery suppression (b) in hypothenar
space and Guyon’s canal
neuropathy, with the lesion involving only the sensory
branch. Type III is a pure motor neuropathy, with the
lesion proximal to the branch supplying the hypothenar
muscles. Type IV spares the hypothenar muscles with
the lesion distal to the hypothenar muscle branch.
Type V involves only the adductor pollicis and first
dorsal interosseous muscles. The present case is type III
according to Shea and McClain and type II according to
the Wu classification.

Ganglions are the most common causes of
Guyon’s canal syndrome. Other causes include giant cell
tumors, neurilemmomas, repetitive trauma, vascular lesions,
anomalous muscles, carpal fractures and rheumatoid arthritis.
Lipoma is a rare cause of nerve compression at this site.
The cellular origin of lipoma in Guyon’s canal is debatable. a b
[10]
Balakrishnan et al. reported a case in which the branches Figure 3: Intra-operative pictures showing (a) dissection and (b)
of the ulnar nerve were splayed by the tumor; these enucleated specimen and underlying ulnar nerve and its branches

Plast Aesthet Res || Vol 1 || Issue 3 || Dec 2014 119