DOI:10.2214/AJR.04.0920
AJR 2005; 185:1350-1354
© American Roentgen Ray Society
Chronic Granulomatous Lesions After Thyroidectomy: Imaging Findings
Jill E. Langer1,
Erika Luster1,
Steven C. Horii1,
Susan J. Mandel2,
Zubair W. Baloch3 and
Beverly G. Coleman1
1 Department of Radiology, University of Pennsylvania Medical Center, 3400
Spruce St., Philadelphia, PA 19104.
2 Department of Medicine, University of Pennsylvania Medical Center,
Philadelphia, PA 19104.
3 Department of Pathology, University of Pennsylvania Medical Center,
Philadelphia, PA 19104.
Received June 10, 2004;
accepted after revision November 2, 2004.
Address correspondence to J. E. Langer.
Abstract
OBJECTIVE. The purpose of this report is to describe the imaging
appearance of granulomatous inflammation in the neck presenting as a late
complication in patients who have undergone thyroidectomy for differentiated
thyroid carcinoma.
CONCLUSION. Granulomatous inflammation can occur as a palpable mass
in the operative bed of asymptomatic patients who have undergone thyroidectomy
for thyroid carcinoma. The diagnosis may be suggested when the lesion shows
the sonographic appearance of a poorly defined hypoechoic lesion or lesions
with a central echogenic nonshadowing focus, often within the
sternocleidomastoid muscle. These lesions may appear as complex cystic masses
on CT and MRI and may have increased activity on PET. Percutaneous biopsy can
establish the diagnosis of an inflammatory lesion and can exclude underlying
active infection and malignancy.
Introduction
The most common indications for total thyroidectomy are malignancy and
benign thyroid enlargement. The immediate surgical complications of the
procedure include hypocalcemia, recurrent laryngeal nerve injury, hemorrhage,
and infection
[1-3].
Beyond the perioperative period, tumor recurrence becomes the primary concern
in those patients who have had thyroidectomy for malignancy. Patients are
monitored for recurrence by various methods including clinical examination of
the neck; serum thyroglobulin levels; sonography of the neck; and, in some
cases, total-body radioactive iodine scanning
[4-8].
If a neck mass is detected on imaging or at physical examination, fine-needle
aspiration of the lesion is recommended. The purpose of this report is to
describe the imaging findings of granulomatous inflammation presenting as a
palpable focal mass in the surgical bed occurring as a late complication of
thyroidectomy for thyroid carcinoma.
Materials and Methods
A retrospective review of the pathology results of all patients who
underwent sonographically guided fine-needle aspiration of a neck mass or of
abnormal-appearing paratracheal or cervical lymph nodes after previous total
thyroidectomy for thyroid malignancy in our institution's thyroid carcinoma
evaluation center was performed. From September of 1999 to June 2004, the
center performed sonographically guided fine-needle aspiration on 156 patients
who have had one or more focal lesions detected by sonography. In four
patients (2.5%), the fine-needle aspiration was consistent with the diagnosis
of a granulomatous inflammatory lesion without microorganisms or malignancy.
The imaging findings of these four patients are reported.
All four patients were referred for diagnostic sonography and
sonographically guided fine-needle aspiration of a palpable neck lesion.
Sonography evaluation was performed using an ATL scanner (Philips Medical
Systems) with a 12-5-MHz linear-array transducer. Fine-needle aspiration was
performed under direct sonographic guidance using an 8-5-MHz curvilinear
transducer and a 25-gauge needle. All specimens underwent cytologic and
microbiologic evaluation. In addition, one patient had a PET scan, and another
patient had a both a CT scan and MR examination of the neck. CT was performed
on a LightSpeed Plus CT scanner (GE Healthcare) and MRI was performed on a
1.5-T scanner (Signa, GE Healthcare) using a head and neck surface coil. One
patient had surgical excision of the palpable lesion.
Results
The clinical and pathologic findings are summarized in
Table 1. The patients included
three men and one woman with an age range of 47 to 62 years when the lesions
were palpated. All four patients had previous total or near-total
thyroidectomy for well-differentiated thyroid carcinoma. All of the primary
thyroid tumors were confined to the thyroid without evidence of extrathyroidal
extension or paratracheal lymph node involvement. The patients were referred
for diagnostic sonography and sonographically guided fine-needle aspiration 6
to 60 months after thyroidectomy to evaluate a nontender palpable abnormality
in the neck without other symptoms. The palpable lesion was contralateral to
the original tumor in two patients and ipsilateral in one patient. One patient
(patient 4) developed an ipsilateral neck lesion 1 year after thyroidectomy
that was resected at another institution. Pathologic analysis showed
granulation tissue; multinucleated giant cells; and fibrosis without
microorganisms, foreign body, or malignancy. Four years later, he developed a
contralateral palpable abnormality and presented to our institution for
further analysis. All patients had serum thyroglobulin levels of less than 1
ng/mL at the time of presentation.
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Fig. 1 —47-year-old man (patient 1 in
Table 1) who developed palpable
left-sided lesion 6 months after thyroidectomy for right 3-mm papillary
carcinoma. Transverse sonogram of neck at level just below hyoid shows 6
x 10 x 11 mm hypoechoic lesion with several central echogenic foci
in left sternocleidomastoid muscle (large arrow) and similar
appearing 5 x 5 x 7 mm lesion in anterior midline subcutaneous
tissues (small arrow). Fine-needle aspiration biopsy of both lesions
was consistent with granuloma. Repeat sonograms (not shown) obtained 2 years
later showed no change in the appearance of these lesions.
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Fig. 2 —62-year-old man (patient 2 in
Table 1) who underwent
thyroidectomy for rightsided 5.4-cm minimally invasive follicular carcinoma
presented 29 months after initial surgery with vague palpable abnormality.
Transverse sonogram of left neck shows ill-defined lesion measuring 14 x
14 x 42 mm in left sternocleidomastoid muscle that has central
hyperechoic focus (arrow). Fine-needle aspiration biopsy was
consistent with granuloma. Repeat sonograms (not shown) obtained 19 months
later showed no change.
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Neck sonography showed a poorly marginated hypoechoic lesion with one or
more central echogenic foci that corresponded to the palpable abnormality in
all four patients (Figs. 1,
2,
3A,
3B,
3C,
3D, and
4). In addition to the palpable
lesion, two patients had a similar-appearing second smaller lesion in close
proximity to the palpable lesion; the remainder of the sonographic
examinations were unremarkable in all four patients. The lesions ranged in
size from 5 to 42 mm in longest diameter
(Table 1). Three of the lesions
were centered in the sternocleidomastoid muscle, one within the anterior
subcutaneous tissues of the neck, and two within the paratracheal region, both
of these occurring in the same patient.
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Fig. 3A —57-year-old woman (patient 3 in
Table 1) who underwent total
thyroidectomy for 4-mm follicular carcinoma with minimal capsular invasion
presented 5 years after surgery with palpable abnormality in right neck Axial
T2-weighted fat-suppressed fast spin-echo image of neck shows two foci with
bright signal: one within right paratracheal region (long arrow) and
smaller similar-appearing, more anterior lesion (short arrow)
extending into adjacent muscle.
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Fig. 3B —57-year-old woman (patient 3 in
Table 1) who underwent total
thyroidectomy for 4-mm follicular carcinoma with minimal capsular invasion
presented 5 years after surgery with palpable abnormality in right neck Axial
T1-weighted image after IV gadolinium administration shows ring enhancement of
both lesions (arrows). Sonogram obtained at time of fine-needle
aspiration (not shown) revealed 17 x 26 x 41 mm complex, partially
cystic lesion in right thyroidectomy bed. Surgical excision showed only
fibroadipose tissue, necrosis, lymphoid tissue, and both acute and chronic
granulomatous inflammation.
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Fig. 3C —57-year-old woman (patient 3 in
Table 1) who underwent total
thyroidectomy for 4-mm follicular carcinoma with minimal capsular invasion
presented 5 years after surgery with palpable abnormality in right neck
Longitudinal sonogram obtained 18 months after excision of inflammatory lesion
shows hypoechoic heterogeneous lesion measuring 18 x 18 x 42 mm
that has several internal echogenic foci and smaller adjacent lesion measuring
8 x 12 x 13 mm (not shown).
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Fig. 3D —57-year-old woman (patient 3 in
Table 1) who underwent total
thyroidectomy for 4-mm follicular carcinoma with minimal capsular invasion
presented 5 years after surgery with palpable abnormality in right neck Axial
contrast-enhanced neck CT scan obtained shortly after C shows
hypoattenuating lesion in right paratracheal region (arrow).
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Fig. 4 —55-year-old man (patient 4 in
Table 1) who had thyroidectomy
for right 4-cm follicular variant of papillary carcinoma. Four years earlier
patient had granuloma resected from right neck. Five years after
thyroidectomy, patient noted left-sided neck lesion. Sonogram shows complex
lesion (electronic calipers) measuring 7 x 13 x 16 mm in
left sternocleidomastoid muscle that has central markedly echogenic focus
surrounded by hypoechoic zone.
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Sonographically guided fine-needle aspiration was performed on the four
palpable lesions and one of the adjacent smaller lesions (patient 1). In
addition, one patient (patient 2) underwent fine-needle aspiration of a single
lesion both at 29 and 49 months after thyroidectomy.
In all five lesions, fine-needle aspiration showed granulation tissue,
histiocytes, and neutrophils without evidence of malignancy and stains for
microorganisms were negative. In addition, two patients (patients 2 and 4) had
negative results for microbacterial and fungal cultures of the fine-needle
aspiration specimens. Thyroglobulin analysis was performed of the fine-needle
aspirate of both lesions in one patient (patient 1), and an abnormal
thyroglobulin level was not detected.
Additional imaging was performed in two patients. One patient (patient 2)
had noted a palpable abnormality in the left neck 29 months after
thyroidectomy for a minimally invasive right follicular carcinoma. Neck
sonography showed an ill-defined hypoechoic lesion with a central echogenic
focus (Fig. 2). Sonographically
guided fine-needle aspiration showed granulation tissue and giant cell
reaction without microorganisms or malignancy. Four years after thyroidectomy,
a PET scan was obtained (not shown); it depicted abnormal uptake in the left
neck corresponding to the site of the palpable lesion. A repeat sonogram
showed no interval change. Repeat fine-needle aspiration was performed and
again showed only granulation tissue and giant cell reaction. Microbiologic
and fungal cultures of the specimen were negative.
One patient (patient 3) underwent MRI and CT of the neck. At the time of
the palpable lesion, MRI showed a complex enhancing mass in the right
paratracheal region (Figs. 3A
and 3B) and a smaller
similar-appearing lesion more superiorly in the paratracheal region. The
lesions had central low signal on T1-weighted images and high signal on
T2-weighted images. Sonography showed a 17 x 26 x 41 mm hypoechoic
mass in the paratracheal region and a smaller similar-appearing 8 x 12
x 13 mm more superior paratracheal lesion. Fine-needle aspiration of the
larger lesion showed only inflammatory cells without evidence of malignancy.
Because of a high clinical concern of recurrence, the patient underwent
surgical excision of the lesions and paratracheal lymph node dissection.
Surgical pathology yielded only fibroadipose tissue, necrosis, lymphoid
tissue, and both acute and chronic granulomatous inflammation without evidence
of malignancy or foreign body. All stains and cultures for microorganisms were
negative. Surveillance sonography 14 months later showed two complex lesions
in the right paratracheal region, similar in appearance to the preoperative
lesion, measuring 18 x 18 x 42 mm and 8 x 12 x 13 mm
(Fig. 3C). CT of the neck
performed at this time showed a lesion in the right paratracheal region
(Fig. 3D) with a
low-attenuating center and enhancing rim. Because the patient was asymptomatic
and the serum thyroglobulin level remained undetectable, the patient is
undergoing routine annual monitoring for recurrence without further
intervention.
Discussion
The definitive treatment for thyroid cancer is a total or near-total
thyroidectomy often followed by radioactive iodine ablation therapy of any
remaining thyroid tissue or radioactive iodine-avid metastases. This approach
is curative in most patients with well-differentiated thyroid cancer.
Recurrence occurs in approximately 10% of patients, most commonly in the neck
region [4].
Patients at highest risk are the elderly and those with tumors that have
aggressive histiologic features, are larger than 4 cm, and show extrathyroidal
invasion or lymph node involvement at the time of resection
[4-6].
However, all patients, regardless of risk, are followed postoperatively
because low-risk patients account for up to 50% of patients with recurrence
[4].
Patients are monitored for neck recurrence by various methods including
clinical examination, serum thyroglobulin levels, sonography, and when
indicated, total-body radioactive iodine scanning
[4-8].
Among these methods, high-frequency sonography has shown to be the most
sensitive in the detection of thyroid carcinoma
[4,
6]. The traditional management
of suspected recurrence is fine-needle aspiration for cytologic analysis. More
recently, the technique of analyzing the fine-needle aspiration specimen for
thyroglobulin has been added
[4] and shows increased
sensitivity for detecting recurrence.
On sonography, metastatic disease is most commonly detected in the regional
lymph nodes—that is, the paratracheal, anterior, and posterior jugular
chains—and is less commonly detected in the thyroid bed. Lymph nodes
involved by differentiated thyroid cancer may have cystic change,
calcifications, enlargement, or a more rounded shape
[4-9].
Recurrence to the thyroidectomy bed typically appears as a solid hypoechoic
infiltrating mass on sonography
[5,
6].
The presence of a palpable lesion in these four patients raised concern for
recurrent thyroid carcinoma, and the patients were appropriately referred for
diagnostic sonography and sonographically guided fine-needle aspiration of the
lesions. However, the sonographic appearance of these lesions was not typical
for a lymph node or a thyroid bed recurrence. The appearance of the lesions,
an ill-defined hypoechoic lesion with a focal central echogenic focus, is more
similar to that of a foreign-body granuloma
[10]. Gritzmann et al.
[9] described a hypoechoic
lesion with an echogenic central focus in the neck of a postthyroidectomy
patient that proved to be a foreign-body granuloma occurring from a suture.
The appearance of that lesion is similar to that reported in this article.
However, there was no evidence of a suture or other foreign body in the one
patient who had surgical excision at our institution or by report in the one
patient who had previous excision of a contralateral lesion (patient 4). The
location of the lesion or lesions in three patients (patients 1, 2, and 4) was
also atypical for recurrent thyroid malignancy. The lesions were located in
relatively superficial locations, occurring within the sternocleidomastoid
muscle and the adjacent superficial subcutaneous tissues, unusual places for
recurrence in the absence of extrathyroidal extension or muscle invasion at
the time of resection.
The findings of these granulomatous lesions on other imaging techniques
such as MRI and CT are nonspecific. The scans showed a complex cystic lesion
with an enhancing rim that would be compatible with cystic lymphadenopathy and
with a postoperative abscess or inflammatory lesion
[3]. Patient 2 had undergone
PET, which showed uptake in the region of the inflammatory mass raising
concern for recurrence. Uptake of the PET radionuclide secondary to chronic
inflammation in a patient who has had thyroidectomy for carcinoma has been
reported [11]. In that case, a
chronic granuloma was caused by polytetrafluoroethylene injection that had
been used as an operative technique to isolate the recurrent laryngeal
nerve.
In conclusion, chronic granulomatous inflammation can occur as a palpable
mass or masses in the operative bed of otherwise asymptomatic patients who
have undergone thyroidectomy for thyroid carcinoma. Often these patients will
be referred to undergo sonography and fine-needle aspiration. The diagnosis
may be suggested when the lesion shows the typical sonographic appearance of a
hypoechoic lesion with a central echogenic focus, often within an atypical
location such as the sternocleidomastoid muscle or subcutaneous tissues of the
neck in a patient at low risk for recurrence. These lesions may appear as
complex cystic masses on CT and MRI and may have increased activity on PET.
Percutaneous biopsy will establish the diagnosis of an inflammatory lesion and
can exclude underlying active infection and malignancy.
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Abstract
Introduction
