Keywords
mesenteric lymphatic malformation - small bowel volvulus - counter clockwise barber
pole sign - CT angiography
Introduction
A 6-year-old female patient presented with a 2-day history of severe periumbilical,
colicky abdominal pain. She had six to eight episodes of non-bilious vomiting since
the onset of her symptoms, and no bowel movements had been recorded for the preceding
2 days. The patient had two similar previous episodes that resolved spontaneously.
The patient had been evaluated at outside health centers on multiple occasions. She
was investigated with an abdominal sonography and barium meal follow-through examination.
Both examinations were not available for review and were reportedly normal.
On physical examination, vital signs were within normal limits. Abdomen was soft and
not distended. Tenderness was present in the umbilical region. No palpable mass was
felt. Bowel sounds were normal. Routine laboratory investigations were within normal
limits. Abdominal X-rays were performed to exclude bowel obstruction, which showed
few non-specific bowel loops with a suggestion of a soft tissue opacity in the central
abdomen. There was no definite evidence of bowel obstruction or perforation. Ultrasonography
of abdomen showed few fluid-filled cystic spaces in the periumbilical and adjacent
supravesical regions. There was evidence of twisting of mesentery along with mesenteric
vessels. Multiple prominent lymph nodes were observed in the central abdomen and right
iliac fossa. Based on sonographic observation, the possibility of mesenteric lymphatic
malformation with small bowel volvulus was considered. There was no peritoneal fluid.
No evidence of bowel wall thickening was demonstrated on sonography. Doppler examination
suggested parallel, twining configuration of proximal mesenteric vessels at the central
abdomen. Evaluation of distal mesenteric vessels and bowel wall was unsatisfactory.
Contrast-enhanced multidetector computed tomography (MDCT) examination of abdomen,
which was performed to exclude bowel ischemia, demonstrated multiple thin-walled peripherally
enhancing fluid-filled cystic spaces in mesentery located in the central abdomen ([Fig. 1A]). There were features of small bowel volvulus with mesenteric twisting ([Fig. 1B]). Proximal mesentery showed counterclockwise twisting of more than 360 degrees.
There was mesenteric edema ([Fig. 1B]) and narrowing of the superior mesenteric artery (SMA), approximately 3 to 4 cm
from its origin ([Fig. 1C]). Maximal intensity projection (MIP) projection and 3-D volumetric display showed
the counterclockwise barber pole sign ([Fig. 1C], [D]). There was no evidence of intestinal obstruction or ischemia.
Fig. 1 (A) Axial contrast enhanced CT examination demonstrates cystic lesion in the mesentery
(circle). There are clusters of mesenteric vessels with adjacent thickened mesentery
(arrow). (B) Thickened mesentery around a pedicle is better demonstrated more proximally (arrow).
(C) The 3-D angiographic views show barber's pole sign (open arrow) and narrowing of
SMA. (D) Picture of a barber's pole with alternating stripes. CT, computed tomography; SMA,
superior mesenteric artery.
On diagnostic laparoscopy, a yellowish, fluctuant soft swelling in the mesentery of
mid-ileum was seen in association with associated mid-ileal volvulus. The bowel loops
were clustered together and appeared pink and healthy. Laparotomy confirmed mesenteric
lymphatic malformation and volvulus of small bowel ([Fig. 2A]). The lymphatic malformation was acting as the fulcrum of rotation of the mid-ileum.
The mass was adherent to adjacent ileal segments, needing resection of the affected
bowel segment, and end-to-end anastomosis of the uninvolved bowel. On pathological
examination, the small bowel segment measured 9.0 cm in length with an attached mesentery
of 3.5 cm length. The mesentery had a glistening nodular appearance. On slicing of
the mesentery, multiple cysts of variable sizes ranging from 0.2 to 3 cm, containing
pale pinkish fluid were noted ([Fig. 2B]). Histopathological examination showed variably sized, thin-walled lymphatic-like
channels extending up to muscularis mucosa lined with flattened lining. Lymphatic
spaces were seen amidst adipose tissue and fibromuscular stroma ([Fig. 2C]). The features were consistent with a macrocystic lymphatic malformation. The patient's
postoperative course was uneventful, and the patient was stable and asymptomatic on
follow-up.
Fig. 2 (A) Operative photograph showing mesenteric volvulus. No evidence of bowel infarction
was noted. Specimen photograph (B) shows focal areas of mesenteric cystic masses (open arrow). (C) Photomicrograph (x20) shows part of the small bowel (upper left corner) with adjacent
cystic spaces of varying size. Spaces are lined by flattened cells and contain proteinaceous
material with lymphocytes. Finding is consistent with lymphatic malformation.
Discussion
Lymphatic malformations are a frequently encountered pediatric disease, representing
6% of benign tumors in children[1]
[2] In pediatric patients, lymphatic malformations are often located in the cervico-facial
region and in the axilla. Intra-abdominal localization is less frequent, with a reported
incidence of <5 % of the total.[2]
[3] Lesions usually manifest in early childhood and are characterized by a slow, insidious
growth. Although the malformation is mostly asymptomatic, some may lead to complications,
such as secondary infection, rupture, hemorrhage, volvulus, or intestinal obstruction,
particularly when the lesion increases in size and volume.[1] As a cause of small bowel volvulus, the mesenteric lymphatic malformations constitute
a relatively uncommon entity.[4]
[5] When small bowel volvulus is encountered, it is a surgical emergency and needs prompt
diagnosis and management. Diagnosis of volvulus in older children or adults can be
delayed due to non-specific clinical manifestations. It is important to make an early
diagnosis to expedite surgical intervention and to avoid intestinal ischemia.
Imaging plays a vital role in defining the diagnosis by demonstrating multiple fluid-filled
cysts in the mesentery along with the appearance of small bowel volvulus. Accurate
diagnosis can be suspected by sonography[6] or by CT. While selecting the choice of imaging modalities in children, the concern
for radiation needs to be weighed against the need for accurate, unambiguous diagnosis
and the promptness with which the final diagnosis can be reached. Due to technical
limitations, ultrasound examination often fails to provide accurate information about
the presence and extent of bowel ischemia or fails to detect small, peripherally located
mesenteric lesions predisposing to volvulus, as exemplified by our patient. In the
acute clinical setting, CT examination is often performed as a definitive investigation.
MDCT is considered the most useful examination for evaluation of suspected small bowel
volvulus.[7] Radiological interpretation requires, apart from demonstration of the lesion, additional
observations, such as signs of cyst rupture, bowel malrotation, volvulus, or bowel
ischemia. The presence of volvulus can occasionally be suspected on sonographic examination
by observing the relation of the SMA to the vein. Whirled appearance of mesenteric
veins around the SMA provides a clue to malrotation. Whirlpool sign is seen in majority
of cases of small bowel volvulus on MDCT. It refers to the whirling of branches of
superior mesenteric vessels around the main axis of the vessel. The sign basically
depicts the axial appearance of the mesentery around the axis of the SMA. Conversely,
the “barber pole sign” refers to the lateral profile of the mesentery, along the long
axis of mesenteric vessels, when obtained from the contrast-enhanced 3-D rendered
dataset of CT. The barber pole sign is due to the multiple stack of intertwining branches
of SMA and superior mesenteric vein (SMV) along the path of the mesentery. The barber's
pole, which is typically displayed outside barber shops, is characterized by alternating
strips of color, in combination of white, red, and blue around a pole. ([Fig. 1D]). This imaging sign is coined due to the resemblance of mesenteric vessels to a
Barber's pole. MDCT examination is a better suited technique for identifying volvulus
and its complications. Interrogation of the axial CT axial dataset, viewed craniocaudally,
allows the counterclockwise rotation of the mesentery to be unambiguously appreciated.
The sweeping of the mesenteric veins around the SMA is best visualized just beyond
the duodenojejunal (DJ) flexure.[6] Vessels appear like hockey sticks, with SMA in the position of the hook. CT also
provides information about mesenteric edema and bowel ischemia. Enhancement pattern
of the bowel indicates status of the viability of the bowel loops and possible bowel
gangrene. CT angiography, performed as part of CT evaluation, shows narrowing or occlusion
of SMA. Vascular narrowing, as seen in our patient, is an early sign that indicates
the potential for bowel infarction. The barber pole sign is occasionally reported
in malrotation, complicating mesenteric lymphatic malformation. This sign, also known
as ‘counterclockwise barber pole sign’ was originally described by Buranasiri et al[8] on an angiographic examination in a patient with counterclockwise malrotation. Reference
to the term “reverse barber pole” is made to imply the counterclockwise rotation of
the bowel. Hence, it appears appropriate to describe this sign as counterclockwise
barber pole sign as the terminology also directly implies the axis of bowel rotation.
Although the whirlpool sign and the barber pole sign refer to the same phenomenon
viewed from different orientations, the whirlpool sign is more often seen in the proximal
mesentery, while the barber pole sign can be detected anywhere along the mesenteric
axis. Comparison of the exact incidence of both signs is difficult as there are not
many large series reported in the literature. One report evaluating mesenteric volvulus
with CT reported the presence of the whirlpool sign in more than half of the cases.
No specific reference was made regarding the barber pole sign.[7] Description of the barber pole sign in association with mesenteric lymphatic malformation
is limited to case reports.[6] Occasionally, this sign is reported on CT angiography examination in adults[9] and older children. Rarely, this sign is seen in the absence of bowel malrotation.[9] The 3-D CT angiographic reconstructions and MIP projection of small volumetric dataset
of the area of interest enable illustration of this imaging sign most evidently. The
length of twisted vessels (barber pole length) will depend upon the extent of rotation
and, hence, can vary greatly. Selected, small volume 3-D data processing and surface/MIP
rendering around the mesenteric axis will help visualization of a short segment twist
in patients with subtle mesenteric rotation.
Conclusion
A case of mesenteric lymphatic malformation presenting with volvulus of small bowel
is described. The presence of “counterclockwise barber pole sign” was shown in the
reconstructed MDCT imaging datasets, thereby substantiating the diagnosis. The basis
of this not so well-known sign is presented, and we discuss how it differs from a
more classical sign, the ‘whirlpool sign’ of mesenteric volvulus. The importance of
this sign is highlighted as a means of prompt appreciation of signs of volvulus and
in the prediction of bowel ischemia secondary to vascular compression. We also discuss
the role of ultrasonography and MDCT in the clinical context of mesenteric volvulus.
