Introduction
Eosinophilic pancreatitis (EP) is an extremely rare etiology of chronic pancreatitis,
and only a few cases have been reported [1]
[2]. It is characterized by diffuse or localized eosinophilic infiltration of the pancreas
and elevated IgE levels. Differential diagnosis between EP and pancreatic cancer (PC)
is challenging because clinical symptoms and auxiliary exams (laboratory tests and
radiological evaluation) may be rather similar [3].
Routine endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for resectable
pancreatic lesions is controversial [4]. Some experts advocate that routine FNA may detect a non-surgical condition and
therefore avoid an unnecessary operation and related complications. Conversely, EUS-FNA
presents a substantial false-negative rate and may be associated with some adverse
events, which might postpone or impair a curable resection [5]
[6]. We report a case that illustrates the aforementioned debate.
Case report
A 37-year-old man with a 4-month history of weight loss, obstructive jaundice, pruritus,
and nausea and vomiting was admitted with an acute clinical complaint of fever, cough
and dyspnea. He reported alcohol abuse for 15 years but denied any family medical
history of PC. Physical examination revealed normal general appearance (body mass
index = 21 kg/m2) but jaundice (2 +/4 +). Abdominal examination showed neither abdominal pain nor
palpable masses. Laboratory tests were as follows: hemoglobin, 12.1 g/L; leukocyte
count, 9.3 × 109/L; neutrophils, 5.6 × 109 (56 %); eosinophils: 0.12 × 109 (12 %) (reference range: 0.0 – 0.06 × 109); total bilirubin 3.97 mg/dL (direct bilirubin: 3.52 mg/dL); alkaline phosphatase,
769 U/L; gamma-glutamyl transferase, 591 U/L; AST, 76 U/L; ALT, 72 U/L; and normal
CA, 19.9. Hepatitis serology and autoimmune tests were negative.
Abdominal ultrasound showed biliary dilation but no cause for obstruction. Magnetic
resonance cholangiopancreatography revealead biliary dilation due to an abrupt irregular
narrowing in the distal common bile duct (CBD) without evident lesion associated with
pancreatic body and tail atrophy and a normal pancreatic duct. Finally, abdominal
computed tomography (CT) showed a 20-mm mass in the head of the pancreas, hypoattenuating,
with no vascular invasion ([Fig. 1]).
Fig. 1 EUS image showing a hypoechoic pancreatic head mass.
Endoscopic ultrasound (EUS) followed by endoscopic retrograde cholangiopancreatography
(ERCP) to evaluate the mass and perform biliary drainage was indicated. EUS demonstrated
a hypoechoic pancreatic head mass measuring 20 mm and a CBD dilatation. EUS-FNA was
performed with a 22-gauge needle (Expect Slimline, Boston Scientific, Marlborough,
Massachusetts, United States) but cytology was inconclusive.
ERCP demonstrated mild biliary duct dilatation due to a regular distal biliary stricture,
suggesting pancreatic extrinsic compression ([Fig. 2a]). Transpapillary forceps biopsy and brush cytology were negative for malignancy.
A 10 Fr × 7-cm plastic stent placement ensured adequate CBD drainage ([Fig. 2b]).
Fig. 2 a ERCP showing a distal biliary stricture; b Biliary drainage with 10 Fr × 7 cm plastic stent.
After the negative sample results, a multidisciplinary group discussed surgery versus
a new attempt at EUS-FNA. An EUS-FNA was indicated, and once again, we used a 22-gauge
needle (Expect Slimline, Boston Scientific, Marlborough, Massachusetts, United States).
The new cytological evaluation showed massive pancreatic eosinophilic infiltration
without a considerable increase in the presence of IgG4 positive cells, consistent
with eosinophilic pancreatitis ([Fig. 3]).
Fig. 3 Cell block, hematoxylin-eosin staining, 400 × Zoom, showing eosinophils in the pancreas.
After the diagnosis, the patient was also diagnosed with eosinophilic pneumonia and
treated with systemic corticosteroids for 5 weeks.
Post-treatment contrast abdominal CT revealed mass shrinking from 20 mm to 12 mm without
biliary tract dilation ([Fig. 4]). Repeat complete blood count showed no elevation of serum IgG4 (121 mg/dL), hemoglobin
16.0 g/L, leukocyte count 8.3 × 109/L, neutrophils 4.6 × 109 (46 %), eosinophils: 0.02 × 109 (2.0 %), total bilirubin 0.37 mg/dL, alkaline phosphatase 63 U/L, and gamma-glutamyl
transferase 132 U/L.
Fig. 4 Post-treatment CT study revealing a mass shrinking and no biliary dilation.
At 1-year follow-up, the patient is asymptomatic on a low dose of systematic corticosteroids
even after biliary stent removal.
Discussion
EP is a rare etiology of chronic pancreatitis characterized by localized or diffuse
eosinophilic infiltration of the pancreas and increased serum IgE [3]. Usually, the patient presents with a pancreatic mass due to eosinophilic inflammatory
infiltration associated with obstructive jaundice, as in our case [2]
[3]. Many etiologies for EP have been suggested and published case reports include malignancy,
parasitic infection, hypersensitivity to medications (e. g., carbamazepine), milk
allergy, atopic diseases, newborn infant of a diabetic mother, and as an association
with hypereosinophilic syndrome or eosinophilic gastroenteritis [1]
[7].
A diagnosis of EP is often made based on hypereosinophilic syndrome or eosinophilic
gastroenteritis criteria in patients presenting with gastrointestinal symptoms who
exhibit eosinophilic infiltration in histological/cytological samples [3]
[4]
[8].
Diagnostic criteria for hypereosinophilic syndrome are as follows: peripheral eosinophil
count higher than 1.5 × 109 for 6 months; past medical history of rhinitis, asthma or other allergic diseases;
eosinophilic infiltration of other organs (digestive system, skin and/or heart); nad
exclusion of other causes for eosinophilia such as parasitic infestations or leukemia
[3]
[8].
Regarding the eosinophilic gastroenteritis, which our patient had as well, the diagnostic
criteria include presence of abdominal pain, vomiting, nausea, diarrhea, loss of appetite
or any other digestive symptom; intestinal sampling showing eosinophilic infiltration
and ruling out parasitic infection; and no involvement of organs outside the gastrointestinal
tract [4].
The main differential diagnosis includes autoimmune pancreatitis (AIP) and PC [3].
EP is difficult to distinguish from AIP because they present with similar clinical
symptoms and radiologic results [3]
[7]. However, subtle differences may favor one over the other. [Table 1] outlines characteristics that may help differentiate EP from AIP.
Table 1
Distinct characteristics of eosinophilic and autoimmune pancreatitis.
|
Autoimmune pancreatitis
|
Eosinophilic pancreatitis
|
|
Aspect of the pancreas
|
Enlarged pancreas (“sausage-like”)
|
Focal or diffuse
|
|
Histopathological findings
|
Lymphocytes
|
Eosinophils
|
|
Immunoglobulins
|
Elevated serum IgG4
|
Elevated serum IgE
|
|
Autoimmune and antinuclear antibodies
|
(+)
|
(–)
|
Both EP and AIP are commonly misdiagnosed as PC due to the similarity of symptoms
and imaging findings. It is important to recognize that some cases of PC are associated
with eosinophilia, which can make the diagnosis of either condition difficult [3].
Definitive diagnosis depends on histological/cytological findings, assessment of serum
tumor marker, absence of pancreatic duct dilation, history of hypereosinophilic syndrome
or eosinophilic gastroenteritis, and response to corticosteroid or/and cromolyn therapy
[4]
[9].
Nearly 7 % of patients undergoing pancreatoduodenectomy for suspected malignancy are
ultimately diagnosed with benign disease. Although some preoperative findings such
as abdominal pain, absence of jaundice, normal pancreatic duct and absence of a mass
or double duct sign on CT might indicate a benign condition, they are not sufficient
to warrant use of conservative therapy [9]. EUS-FNA is an essential procedure for a patient with suspected PC who does not
fit the typical demographics/preoperative findings.
Most cases of EP are diagnosed postoperatively. To avoid such unnecessary surgeries,
adequate assessment of the patientʼs medical history and EUS-FNA for tissue sample
are fundamental [3]
[6]. In our case, even after a negative EUS-FNA, we decided on another FNA because the
patient was young and well-appearing, and had no dilation of the main pancreatic duct.
However, only after the cytological results were we able to correlate the findings
of the patient's clinical history and laboratory tests and diagnosed the hypereosinophilic
syndrome.
There are few reports in the literature of cases of eosinophilic pancreatitis diagnosed
by EUS-FNA [1]
[8]
[10]. As in our patient, adequate control of the disease was achieved using prednisolone
or cromolyn [3]
[10].
Conclusions
In summary, EP is a rare condition that is frequently misdiagnosed with PC. Clinical
history, laboratory tests, radiological exams and tissue sampling are necessary for
a definite diagnosis. Correct and precise diagnosis is crucial and may prevent unnecessary
surgery and allow for noninvasive treatment. EUS-FNA is fundamental if the patient
does not fit the typical findings for PC.
