Y015
False positive diagnosis of a paraganglioma
of the organ of Zuckerkandl
Samir Damji, Rashpal Flora, Jeannie
Todd, Fausto Palazzo, Imperial Healthcare NHS Trust.
Case: A 66-year-old lady was
discovered to have a 3.7cm mass at the aortic bifurcation after being
investigated for back pain. She had a past medical history of endometrial
carcinoma, diagnosed 18 years ago and subsequently underwent a total
hysterectomy and external beam radiotherapy. Following an MDT review, a
suspicion was raised that the lesion may have been a paraganglioma.
Subsequent testing for urinary metanephrines was
negative however a there was a borderline increase in plasma metanephrine of 1290 pmol/L, with
a normal upper limit of 1180 pmol/L. Molecular
genetic testing for familial paraganglioma/phaeochromocytoma did not detect a pathogenic variant. The
patient underwent whole body 68Gallium DOTATATE PET-CT scanning, which identified
avid uptake of tracer and somatostatin receptor positivity in the mass at the
aortic bifurcation, in keeping with a paraganglioma
of the organ of Zuckerkandl. Following review at the
NET MDT a decision was made to proceed with surgical resection and the patient
underwent pre-operative anaesthetic assessment and optimisation with
alpha-blockade. An open resection of the paraganglioma
with lymphadenectomy was performed and the patient made an uncomplicated
recovery and was discharged on the 6th post-operative day. The
histopathological analysis of the mass at the aortic bifurcation showed a 30mm
lymph node infiltrated by a metastatic malignant tumour. The morphology and immunoprofile was in keeping with a metastatic carcinoma of
the female genital tract, likely a poorly differentiated endometrial carcinoma.
There was no evidence of a paraganglioma.
Discussion: Neuroendocrine tumours
arising from extra-adrenal ganglia are rare tumours, however they are associated
with high morbidity and mortality. Whilst the mainstay of treatment is surgical
resection, the diagnosis and localisation is often challenging and complex.
However, with the increasing advancement and availability of PET imaging,
somatostatin analogues have been labelled with positron emitting isotopes such
as Gallium-68, to image somatostatin receptor expressing neuroendocrine
tumours. It has been demonstrated that 68Ga-DOTATATE PET scans can
significantly improve the spatial resolution and lesion detectability compared
to MIBG scintigraphy, CT or MRI. A number of studies have confirmed a
sensitivity between 85%-100% and specificity between 82%-90% in the ability to
diagnose NETs. Although a highly sensitive and specific imaging modality, and
whilst extremely rare the physician must be aware of physiological and
pathological processes which may lead to interpretive errors. We present the
first described metastatic, endometrial carcinoma with somatostain
receptor expression resulting in a false positive diagnosis of a paraganglioma of the organ of Zuckerkandl.