Discussion:
Lymphangiomas are the cystic dilatation, due to malformation
(congenital) or fibrosis (acquired), of lymphatic channels. These are
benign slow-growing cystic masses that cause lymphangiectasia due to
lymphatic flow blockage. Gui et al described these segregated lymphatic
channels as defective channels formed during the embryonic period rather
than a true neoplasm [1]. These are generally reported in young
children and are linked with congenital disruption syndromes such as
Turner syndrome, Down syndrome, and Noonan syndrome [2]. During the
development of an embryo, the disconnection of lymphatic vessels results
in lymph obstruction that is enveloped by endothelial cells [3]. As
a result of this multiloculated lymphangiomas are formed. Whereas
acquired lymphangioma developed due to fibrosis, inflammation, and
lymphatic vessel degeneration [4]. Frequently these lesions are
found in the upper parts of the body mainly the neck and head (75%),
axilla (15%) [5, 6, 7], unusual sites are the pericardium, pleura,
liver, spleen, colon, groin, genital organs, and bones. Lymphangiomas
developing in the adult pancreas comprise less than 1% of all
Lymphangiomas [8].
Until now, only a few cases of lymphangiomas have been reported. The
first case was described by Koch K, in 1913 a benign cyst formed due to
blocked regional lymphatic ducts [9]. In medical literature, to our
best knowledge, less than 85 to 90 cases have been described [10].
Clinical manifestation of pancreatic lymphangiomas is nonspecific and
varies based on the site and size of the cyst[11]. Usually, they are
symptomless and found as incidental findings [8]. when symptomatic
are present, they are in the form of digestive discomfort, pain in the
upper abdomen, or palpable masses. Although benign may invade the
adjacent structure and when involve bordering structures like adrenal
gland patient presents with specific symptoms like acute renal injury
with the breakdown of skeletal muscle fibers.[12]
Hence, the combination of clinical presentation and laboratory
evaluation may help identify the origin of the tumor and make
appropriate diagnoses and differentials. In our case, the patient was
symptomatic, he was a male patient who came with complaints of
epigastric pain for few days. The average size of pancreatic
lymphangiomas is around 12 cm in the greatest dimension [13], but in
our case, the lesion was relatively larger. For evaluation, the CT
pancreas dynamic was performed which revealed a multilocular and
multiseptated homogeneously hypoattenuating/non-enhancing fluid density
omento mesenteric mass predominantly occupying the lesser sac. The
lesion was insinuating within the pancreatic body and tail parenchyma as
well as along the small bowel mesentery with mild mass effect on the
stomach which is anteriorly compressed. It was abutting the left adrenal
gland, which was however normal. The pancreatic head and uncinate
process appeared normal. It was causing displacement of the small bowel
loops and surrounding the transverse colon and splenic flexure.
Generally, pancreatic cystic lesions can be differentiated from
lymphangiomas include pancreatic simple cysts pseudocysts, mucinous
cystic neoplasms, serous cystadenomas, intraductal papillary mucinous
neoplasms, and cystic pancreatic carcinomas. Imaging results may assist
in preoperative diagnosis of upper abdominal lymphangiomas, even though
none of the findings are confirmatory [13]. On Ultrasound scan,
lymphangioma gives the impression as a complex cystic mass with
intra-cystic septation or internal echoes, with or without internal
calcifications. CT scan will reveal a low-density, thin-walled, uni, or
multilobulated cystic mass with thin enhancing endo-cystic septation
[8]. pancreatic cystadenomas share the same imaging findings and may
present in similar ways suspension, can be ruled out on histology.
Pseudocyst in the pancreas usually develops due to chronic or acute
pancreatitis, USG or CT imaging will reflect the finding. These changes
were not present in our case and therefore the possibility of pseudocyst
was low.
Diagnosing pancreatic lymphangioma is highly suspect with the help of
clinical findings and imaging investigations like CT, and EUS combined
with FNA. In our case after clinical evaluation, we did CT which narrow
down our differentials and leads us to ultrasound-guided Fine Needle
Aspiration (FNA). Aspirated fluid was sent for cytology and biochemistry
yielding very high LDH and triglyceride levels, making pancreatic
lymphangioma highly likely and our working diagnosis. Simple cysts,
serous cysts, or lymphangiomas usually yield clear thin, straw-colored
fluids, composed of lymphomononuclear cells. Fluid from mucinous cysts
will produce mucin, which can be detected grossly and microscopically.
Moreover, the aspirated fluid from mucinous cyst will show
mucin-producing columnar epithelial cells in varying amounts, arranged
in papillae, clusters, or singles, these cells may or may not show
cytological atypia. pancreatic Cystic carcinomas characteristically
exhibit cytologically and morphologically malignant cells arranged in
clusters, acinar or papillary patterns [8,13,14]
A definitive diagnosis is made on histopathological examination. Grossly
cystic lymphangiomas are typically soft multilobulated masses containing
serosanguinous or serous fluid. The cyst walls are usually
single-layered cells without any solid areas. Under microscope dilated
lymphatic channels of large and small sizes are seen, which are
separated by thin septa and are intermixed with the pancreatic
parenchyma [13]. Cysts are lined by flattened endothelial cells.
Lymphocytes aggregates may be noticed inside the cysts or adjoining
stromal tissues in Lymphangiomas [8,13]. Histologically
lymphangiomas are classified into cystic, cavernous, and capillary [4,
7 15]. This classification was defined by Wegner in 1877 [16].
2018 International Society for the Study Vascular Anomalies, subclassify
the cystic lymphangioma as macro-cystic lymphatic malformation if cyst
diameter is more than 1 cm, while cavernous lymphangioma is described as
microcystic lymphatic malformation as the cyst diameter is less than 1
cm. Thus, lymphangiomas are classified into microcystic, macrocytic, and
mixed lymphangiomas [17]. Capillary lymphangiomas are formed by
tiny, poorly defined lymphatic vessels comprising of a thick cellular
stroma [7]. Microcystic lymphangiomas are common in areas with dense
connective tissue so decreased muscle expansion, such as the tongue and
lip. Macro-cystic lymphangiomas are more common in areas with loose
connective tissue, like the axilla, neck, and abdomen, so
endothelial-lined channels can easily expand. [18]. Retroperitoneal
macro-cystic lymphangiomas are predominantly multilocular [7]. In
the pancreas, cystic and cavernous and a mixture of these two have been
reported.
The treatment of lymphangioma is based on classification. In macrocytic
or mixed lymphangiomas spontaneous regression usually occurs while it is
rare in microcystic lymphangioma. Old age is more likely associated with
spontaneous [19]. Pathologically, mixed lymphangiomas macrocystic
are comparable but vary from microcystic lymphangioma in the balance of
in and outflow of lymph fluid [19]. In microcytic lymphangioma,
surgery is a reasonable approach because of the lack of spontaneous
regression. While if the patient remains asymptomatic and the lesion is
not increasing, the patient can be managed conservatively with regular
surveillance imaging studies. Surgical resection is the definitive
treatment of lymphangiomas.
Different surgical choices may be considered, like simple cyst excision,
total pancreatic resection, (Whipple procedure or distal
pancreatectomy), which depends on the size and morphology of the cysts
[14]. En-bloc resection of the pancreatic lymphangioma is the
treatment of choice, which was done in the present case. Partial removal
of cyst or aspiration of the content of cyst is not recommended because
it may cause recurrences. Long term prognosis as complete resection of
the pancreatic lymphangioma is excellent [13,20].