Falsn

Ga-

            

                       

se positivneuroend-DOTAT

      

ve localizaocrine tum

TATE PETman

ation of pmor to thT-CT chanagement

 

  

primary mhe pancreaanging thet

mesentericas with e surgical

c

l

ww.sciencedirect.com

a p o l l o m e d i c i n e 1 1 ( 2 0 1 4 ) 1 3 1e1 3 3

Available online at w

ScienceDirect

journal homepage: www.elsevier .com/locate/apme

Case Report

False positive localization of primary mesentericneuroendocrine tumor to the pancreas withGa-DOTATATE PETeCT changing the surgicalmanagement

Rochita Venkata Ramanan a,*, Manish Chandra Varma b,Arunachalam Pudhiavan a

aDepartment of Radiology, Apollo Hospitals, Chennai, Tamil Nadu, IndiabDepartment of Liver Disease and Transplant, Apollo Hospitals, Chennai, Tamil Nadu, India

a r t i c l e i n f o

Article history:

Received 5 April 2014

Accepted 1 May 2014

Available online 24 May 2014

Keywords:

Neuroendocrine tumors

Pancreas

Primary mesenteric

Ga-DOTA PETeCT

False positive

* Corresponding author. No 34 Srinivasa MooE-mail address: rochitav@yahoo.com (R.V

http://dx.doi.org/10.1016/j.apme.2014.05.0070976-0016/Copyright ª 2014, Indraprastha M

a b s t r a c t

Neuroendocrine tumors (NETs) are a group of neoplasms that arise from the neural crest.

They can be predominantly found in the gastrointestinal tract, pancreas, lung and rarely in

the ovary and thymus.

The introduction of b emitting 68Ga-radiolabelled-DOTA peptides in PETeCT for the

imaging of NETs has been giving promising results. But, it is worthwhile to know the

limitations of using Ga-DOTA peptides to minimize the occurrence of false positives. We

report an interesting case of a primary mesenteric neuroendocrine tumor that was mis-

diagnosed as a nodal secondary from a falsely localized primary pancreatic NET as a result

of non-specific physiologic Ga-DOTA uptake in the pancreas. This resulted in an unnec-

essary distal pancreatectomy.

Copyright ª 2014, Indraprastha Medical Corporation Ltd. All rights reserved.

1. Introduction

Neuroendocrine tumors (NETs) are a group of neoplasms that

arise from the neural crest. They can be predominantly found

in the gastrointestinal tract, pancreas, lung and rarely in the

ovary and thymus.

The introduction of b emitting 68Ga-radiolebelled-DOTA

peptides in PETeCT for the imaging of NETs has been giving

promising results. But, it isworthwhile to know the limitations

of usingGa-DOTApeptides tominimize the occurrence of false

rthy Avenue, Off L B Roa. Ramanan).

edical Corporation Ltd. A

positives. We report an interesting case of a primary mesen-

teric neuroendocrine tumor that wasmisdiagnosed as a nodal

secondary from a primary pancreatic NET as a result of non-

specific Ga-DOTA uptake in the pancreas.

2. Case report

We report the case of a 59-year-old female patient, who pre-

sented with complaints of pain in the epigastric region and

chest along with dysphagia for two months. An abdominal

d, Adyar, Chennai, Tamil Nadu 600020, India.

ll rights reserved.

Fig. 2 e Oblique volume rendered CT reconstruction in the

venous phase reveals the mass close to the first loop of the

jejunum and separate from the pancreas. P-Body pancreas,

a p o l l o m e d i c i n e 1 1 ( 2 0 1 4 ) 1 3 1e1 3 3132

ultrasound revealed a spherical hypoechoic mass with

hyperechoic areas in the periphery at the epigastric region,

below and close to the pancreatic body.

This was followed by a contrast enhanced 160 slice helical

CT in the arterial and venous phases. It showed a spherical

solid mass with heterogeneous contrast enhancement

adherent to the duodeno-jejunal flexure and at one point

infiltrating the wall of the jejunum. The mass showed few

calcific foci and hypodense areas within it. The mass was

separate from the pancreas and no focal lesion was found in

the pancreas other than a small cyst in the body. A diagnosis

of gastrointestinal stromal tumor was made on the CT scan.

(Figs. 1 and 2) Guided biopsy of the mass revealed a NET.

It was then decided to perform a Ga-DOTATATE PETeCT.

This showed an increased tracer uptake by the mass with a

SUVmax of 40. In addition, a small area of increased tracer

uptake was also seen in the pancreatic tail region with a

SUVmax of 4.5. (Fig. 3) No corresponding lesion could be

identified on the CT scan. Nevertheless a final diagnosis of a

primary pancreatic NET with adjacent nodal secondaries was

made. Accordingly, the surgical management was changed

from only a wide resection of the mass to a subtotal distal

pancreatectomy with en bloc removal of the mass with

spleen, third and fourth parts of the duodenum and the

proximal jejunum. (Fig. 4).

Histopathology of the mesenteric mass established it to be

a well-differentiated primary mesenteric NET. The resected

pancreatic parenchyma was normal and no lesion corre-

sponding to the increased tracer uptake in the PETeCT ex-

amination could be identified.

H-Head pancreas, St-Stomach.

3. Discussion

Somatostatin is a small, cyclic neuropeptide that is present in

neurons and endocrine cells. It has a high density in the brain,

peripheral neurons, endocrine pancreas and gastrointestinal

tract.

Fig. 1 e Oblique volume rendered CT reconstruction in the

arterial phase reveals a mass inferior to and separate from

the pancreas.

Fig. 3 e Ga DOTATATE PETeCT reveals a focal increased

uptake in the tail pancreas marked within cursors.

Fig. 4 e Surgical specimen reveals the mass (M), distal

pancreas (P), Duodenum (D), Proximal jejunum (J) and

spleen (Sp).

a p o l l o m e d i c i n e 1 1 ( 2 0 1 4 ) 1 3 1e1 3 3 133

The rationale for employment of Ga-DOTA-conjugate pep-

tides in the assessment of SST-receptor (SSTR) expressing NET

relies on the high affinity of these compounds for SSTR.

Ga-DOTA-TATE presents a predominant affinity for SSTR 2.

Although PETwith thenewerGa-DOTA-conjugate peptides like

Ga-DOTA-TOC, Ga-DOTA-NOC, Ga-DOTA-TATE has brought

about dramatic improvements in spatial resolution compared

to the older I-123 and In-111 labeled studies, there are some

limitations in organs with a higher physiological uptake.

The pancreas shows variable uptake of Ga-DOTA-

conjugate peptides. Though all 5 subtypes of SSTR are pre-

sent in the pancreas, the subtype-2 receptor is commonly

found and is located in the islets. Accumulation of islets in one

pancreatic region, frequently the pancreatic head, may cause

an increased uptake mimicking a tumor.

Any area of focal increased uptake that is not physiological

and has a high SUV is considered diagnostic for tumors. The

median SUVmax values are 59.4 � 48.6 for pancreatic NETs,

26.5 � 18.6 for gastrointestinal NETs and 20.4 � 13.5 for lung

NETs.1

Castellucci et al, in their study have found that in cases of

extra-pancreatic NET, several patients showed increased

pancreatic DOTA uptake, either focal or diffuse.2 Since this

uptake remained stable over a period of follow up, they

concluded that this uptake was likely due to physiologic

variability in SSTR expression by pancreatic endocrine cells

and to variability in their anatomic distribution in the organ.

Awareness of this physiologic variability in SSTR expression

and endocrine cell distribution within the pancreas is impor-

tant especially to avoid misdiagnosis of a tumor.

In our case, this kind of misinterpretation led to an un-

necessary resection of the tail pancreas. The fact that the NET

was closely related to the tail pancreas also contributed to

misdiagnosis. This can be avoided by noting the SUVmax

value of physiologic uptake within normal pancreatic tissue,

which is significantly lower than that of NET. This case

highlights the phenomenon of non-specific physiological Ga-

DOTATATE uptake by pancreatic tissue, which can result in

false positive interpretations and the method to prevent such

an error.

Conflicts of interest

The authors declare no conflict of interest whatsoever arising

out of the publication of this manuscript.

r e f e r e n c e s

1. Campana Davide, Ambrosini Valentina, Pezzilli Raffaele, et al.Standardized uptake values of 68Ga-DOTANOC PET: apromising prognostic tool in neuroendocrine tumors. J NuclMed. 2010;51:353e359.

2. Castellucci Paolo, Pou Ucha Javier, Fuccio Chiara, et al.Incidence of increased 68Ga-DOTANOC uptake in thepancreatic head in a large series of extrapancreatic NETpatients studied with sequential PET/CT. J Nucl Med.2011;52(6):886e890.

Apollo hospitals: http://www.apollohospitals.com/Twitter: https://twitter.com/HospitalsApolloYoutube: http://www.youtube.com/apollohospitalsindiaFacebook: http://www.facebook.com/TheApolloHospitalsSlideshare: http://www.slideshare.net/Apollo_HospitalsLinkedin: http://www.linkedin.com/company/apollo-hospitalsBlog:Blog: http://www.letstalkhealth.in/