Vocal cord paralysis secondary to a benign parathyroid cyst: a case ...

Eur Radiol (2008) 18: 2015–2018
DOI 10.1007/s00330-008-0919-8 INTERPRETATION CORNER
E. K. Woo
R. Simo
B. Conn
S. E. J. Connor
Received: 6 October 2007
Revised: 2 January 2008
Accepted: 11 January 2008
# European Society of Radiology 2008
E. K. Woo (*)
Department of Radiology, Stoke
Mandeville Hospital,
Aylesbury, Buckinghamshire, UK,
HP21 8AL
e-mail: eric.woo@buckshosp.nhs.uk
Tel.: +44-1296-316917
R. Simo
Department of Otolaryngology,
Guy’s Hospital,
London, UK
Case report
Vocal cord paralysis secondary to a benign
parathyroid cyst: a case report with clinical,
imaging and pathological findings (2008:6b)
B. Conn
Department of Dental Histopathology,
Guy’s Hospital,
London, UK
S. E. J. Connor
Department of Radiology,
Guy’s Hospital,
London, UK
An 83-year-old man presented with a history of hoarseness,
neck swelling and shortness of breath. There was no history
of dysphagia, voice strain or neck pain. Physical examination
revealed a slight smooth fullness of the right neck,
but no nodularity to suggest cervical lymphadenopathy.
Fibreoptic endoscopy revealed right vocal cord immobility.
No intrinsic vocal cord lesion was identified. This was
consistent with right recurrent laryngeal nerve palsy.
CT was performed through the neck and chest. Signs of a
right vocal cord paralysis were seen. There was thickening
and medial positioning of the right aryepiglottic fold and
dilatation of the pyriform sinus (Fig. 1). The arytenoid
cartilage was anteromedially positioned (Fig. 2). There was
also atrophy of the thyroarytenoid (Fig. 3) and cricoarytenoid
muscles (Fig. 4). A large 3.3-cm (transverse)×3.9cm
(AP)×3.8-cm (craniocaudal) well-defined low-density
lesion was also seen posterior to the right lobe of the
thyroid gland. This extended to the superior mediastinum
and was associated with slight displacement of the trachea
Abstract Parathyroid cysts are uncommon
entities. Symptomatic parathyroid
cysts are extremely rare with
approximately only 200 cases reported
in the literature. Only ten cases have
been reported with recurrent laryngeal
nerve paralysis and none in the radiological
literature. We present a case
of parathyroid cyst and recurrent
laryngeal nerve paralysis with illustrations
of the clinical, radiological
and pathological appearances as well
as discussion on the management of
this condition.
Keywords Parathyroid . Cyst . CT
to the left (Fig. 5). The appearance was in keeping with a
parathyroid cyst.
Excision of the presumed parathyroid cyst was planned.
Preoperative laboratory tests were all within normal limits
(including serum calcium and parathyroid hormone levels).
Intra-operatively, a large cystic lesion was identified
separate from and posterior to the right lobe of the thyroid
gland consistent with a parathyroid cyst (Fig. 6). The
recurrent laryngeal nerve was seen to enter the cyst wall
and therefore sacrificed with excision of the cyst. Pathological
examination revealed a parathyroid cyst with no
malignant features (Fig. 7). Post-operatively, there was
improvement in the patient’s pressure symptoms, but the
vocal cord paralysis remained.
Discussion
Parathyroid cysts are uncommon entities. Symptomatic
parathyroid cysts are extremely rare with approximately
only 200 cases reported in the literature [1]. Only ten cases

2016
Fig. 1 Axial CT scan shows thickening and medial positioning of
the right aryepiglottic fold (arrow) and dilatation of the ipsilateral
pyriform sinus
have been reported with recurrent laryngeal nerve paralysis
[2–6] and none in the radiological literature. From
embryological developments, the parathyroid glands and
therefore parathyroid cysts can be found related to the
thyroid gland (upper parathyroid glands) and the thymus
Fig. 2 Axial CT scan shows anteromedial positioning of the right
arytenoid cartilage (arrow)
Fig. 3 Axial CT scan shows atrophy of the right thyroarytenoid
muscle (arrow)
(lower parathyroid glands). A parathyroid cyst may be
found in the neck or the mediastinum and may mimic a
thyroid or mediastinal lesion [7]. Most are presumed to be
asymptomatic and are occasionally described as incidental
findings in postmortem studies [8]. If they present
clinically, symptoms include dysphagia, odynophagia and
very rarely recurrent laryngeal nerve palsy [5, 6].
Approximately 10% of patients with parathyroid cysts
have hyperparathyroidism [9].
Fig. 4 Axial CT scan shows atrophy of the right cricoarytenoid
muscle (arrowhead)

Fig. 5 Axial CT scan shows a large well-defined cystic lesion
posterior to the right lobe of the thyroid gland extending to the
superior mediastinum and causing minor mass effect. The appearance
is consistent with a parathyroid cyst
Theories of the pathogenesis of parathyroid cysts are
varied and include: development from epithelial remnants
of the third and fourth branchial pouches, fusion of
microcysts present in the normal gland and as parathyroid
hormone retention cysts due to gland hyperfunction. It has
also been proposed that cysts may arise due to the
persistence of Kurtsteiner canals associated with the
developing parathyroid gland [10]. Microscopically, a
parathyroid cyst is composed of a fibrous connective tissue
wall with occasional entrapped islands of parathyroid chief
cells. Cysts may be lined by chief cells that can secrete
parathyroid hormone into the cyst cavity.
The imaging features of parathyroid cysts can be nonspecific.
Ultrasound would show a low echogenic lesion
Fig. 6 Operative view of the parathyroid cyst being delivered to the
neck
2017
Fig. 7 Right picture: (H&E ×100) fibrous cyst wall with incomplete
single-cell thick epithelial lining (arrow). Top left: (H&E ×200) cyst
wall and lining (arrow). Bottom left: (H&E ×20) parathyroid gland
in fat adjacent to cyst
closely related to the posterior aspect of the thyroid gland,
but is difficult to distinguish from a thyroid nodule. A fineneedle
aspiration often contains brownish fluid with
elevated parathyroid hormone level [11, 12]. Technetium
radionuclide scintigraphy may complicate matters by
demonstrating a cold nodule [6].
In our patient, CT was performed to evaluate the cause of
the recurrent laryngeal nerve palsy. Generally, MRI is used
to evaluate a proximal vagal lesion, and CT of the skull
base through to the upper mediastinum is used to evaluate a
recurrent laryngeal nerve (or distal vagal) lesion. CT clearly
demonstrated the signs of a vocal cord paralysis. The cystic
nature as well as its inferoposterior relation to the thyroid
suggested a parathyroid cyst. Less likely differential
diagnoses would include thyroid cyst, cystic hygroma,
thymopharyngeal cyst, thymic cyst and cystic adenopathy.
The lack of circumferential thyroid tissue around the lesion
would not favour a thyroid cyst. Thymopharyngeal and
thymic cysts as well as cystic hygromas are usually
congenital and usually found in the paediatric group.
Cystic hygromas are typically transspatial. Cystic adenopathy
is not found in the visceral space and would be
located lateral to the thyroid and related to the internal
jugular vein and carotid sheath.
Uncomplicated non-functioning parathyroid cysts may
be treated by ultrasound-guided aspiration as there are no
reports of malignancy [5, 6]. Sclerotherapy has been used,
but there is a risk of neurotoxicity [13]. Surgical excision is
recommended for recurrence, functioning parathyroid cysts
or when there are symptoms of dysphagia, dyspnoea or
recurrent laryngeal nerve palsy.
In conclusion, parathyroid cyst is a rare lesion that
should be considered in the differential diagnosis of a
recurrent laryngeal nerve palsy. The imaging findings of a
cystic lesion inferoposteriorly related to the thyroid gland
should strongly suggest the diagnosis.

2018
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Precisely correct answer was received by closing date from:
Shinichi Kan, Sagamihara, Kanagawa, Japan
Manabu Minami, Ibaraki, Japan
Annemie Snoeckx, Zandhoven, Belgium
Vassilios Maniatis, Palini, Greece
Thaworn Dendumrongsup, Songkhla, Thailand
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Precisely correct answer was received by closing date from:
Shinichi Kan, Sagamihara, Kanagawa, Japan
Manabu Minami, Ibaraki, Japan
Annemie Snoeckx, Zandhoven, Belgium
Vassilios Maniatis, Palini, Greece
Thaworn Dendumrongsup, Songkhla, Thailand
N.B.S. Mani, Miami, USA
Luc Vanstraelen, Mol, Belgium
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