Keywords
Follicular carcinoma - Hurthle cell - renal metastasis - thyroid malignancies
Introduction
Hurthle cell carcinoma is a rare variant of follicular carcinoma of thyroid, accounting
for about 3% of all thyroid malignancies.[1] These tumors tend to recur locoregionally, and distant metastases are rather uncommon.[2] However, distant failure represents the most frequent cause of thyroid cancer-related
death in these patients. The most common sites of metastases encountered are lungs
and bones.[3] Renal metastasis is extremely rare. Herein, we present a case of Hurthle cell carcinoma
of thyroid with metachronous renal metastasis. Extensive literature search suggests
it to be the fourth reported case.[2],[4],[5]
Case Report
An otherwise well, 58-year-old lady presented with swelling in the right side of the
neck for 3 years in December 2014 which was rapidly progressing for the past 3 months.
Contrast-enhanced computed tomography (CECT) scan of the neck, thorax, and abdomen
revealed a large heterogeneous mass in the right lobe of thyroid with no evidence
of distant metastasis. Fine-needle aspiration cytology from swelling showed predominantly
Hurthle cells. She underwent total thyroidectomy in January 2015. Histopathologic
examination of postoperative specimen showed features of Hurthle cell carcinoma [Figure 1]. Tumor was seen involving capsule, surrounding soft tissue, skeletal muscle, and
skin. Six lymph nodes (two each from paratracheal, Level III, and central lymph nodes)
were dissected which were all involved by tumor. She was started on levothyroxine
and underwent Iodine-131 whole-body scan, 6-week postsurgery, which showed thyroid
remnant, left cervical Level VI lymph node, and bilateral pulmonary nodules. Hence,
she was administered 150 mCi radioiodine (RAI) therapy thrice at 6-month intervals
till April 2016. Post-third session therapy and Iodine-131 whole-body scan showed
faint uptake in the right neck node. In December 2016, she developed a right cervical
swelling in the neck, and on Iodine-131 whole-body scan, there was no uptake. CECT
scan of the neck, thorax, and abdomen was done which showed multiple right cervical
lymph nodes at Level II, III, IV and supraclavicular region, bilateral pulmonary nodules,
and lytic destruction of left transverse process of D8 vertebra [Figure 2]. A large exophytic lesion (40 mm × 29 mm) was seen arising from the posterior interpolar
region of the right kidney suggestive of renal metastasis [Figure 3]. Thyroglobulin was measured 2625 ng/ml. She was administered palliative radiotherapy
of 20 gray (Gy) in five fractions over 1 week to the neck and 8 Gy in single fraction
to D7–D9 vertebrae. Subsequently, she was started on oral sorafenib in view of progressive
disease.
Figure 1: Histopathologic examination showing features of Hurthle cell carcinoma
Figure 2: Contrast-enhanced computed tomography scan showing right cervical lymph
nodes (a), bilateral pulmonary nodules (b), and lytic destruction of left transverse
process of D8 vertebra (c)
Figure 3: Contrast-enhanced computed tomography scan showing right renal metastasis
Discussion
According to the World Health Organization classification, Hurthle cell thyroid carcinoma
(HCTC) is considered to be an oxyphilic variant of follicular thyroid carcinoma (FTC).[6] Although earlier studies reported inferior survival of these patients with HCTC,[7] a recent study by Bhattacharyya[1] showed similar outcome as compared with patients of FTC. However, it has been seen
that HCTC is associated with higher rates of metastases compared to other subtypes.
Lung and bone are the most common sites of distant metastases.[3] Renal metastasis is a rare occurrence. Exhaustive search of English literature revealed
that our presented case is the fourth case reported [Table 1]. In general, metastatic kidney lesion should ideally be proven by biopsy, but the
diagnosis by imaging may also be acceptable in cases where the lesion is too small
to be biopsied or biopsy is not possible due to medical comorbidities.[4] In the index case, biopsy from the renal lesion was not done in view of strong clinicoradiological
correlation. Treatment of metastatic HCTC is not well defined owing to its low incidence
and hence fewer extensive experience. The management of distant metastases includes
levothyroxine replacement, focal therapy, and systemic treatment (including RAI),
and in patients with RAI-refractory disease, it includes the use of kinase inhibitors.
Focal treatment is indicated in local tumor palliation and orthopedic or neurologic
sequelae, for example, external beam radiotherapy (EBRT) for palliation of the bone
and brain metastasis or surgical fixation for fractures. RAI ablation is difficult
in HCTC as most of them do not uptake RAI, and some of the tumors which show faint
uptake is probably due to the follicular component.[3] Chemotherapy is usually not effective.[8] Among kinase inhibitors, sorafenib is approved by the US Food and Drug Administration
for advanced differentiated thyroid cancer.[9] Similarly, our patient was managed by sorafenib and local EBRT to the neck and D8
vertebrae.
Table 1
Previous published reports of Hurthle cell carcinoma of thyroid with renal metastases
|
Authors
|
Age (years)
|
Sex
|
Renal metastasis diagnosed by
|
Treatment received
|
|
CT – Computed tomography; RAI – Radioiodine; SPECT – Single-photon emission computed
tomography; FDG – Fluoro-deoxyglucose
|
|
Djekidel et al.[1]
|
75
|
Male
|
FDG positron emission tomography-CT scan, magnetic resonance imaging
|
Thyroidectomy, RAI therapy, radical nephrectomy, and palliative radiotherapy to vertebral
metastasis
|
|
Claimon et al.[4]
|
61
|
Female
|
SPECT/CT imaging
|
Thyroidectomy and RAI therapy
|
|
Kushchayeva et al.[6]
|
70
|
Unknown
|
Unknown
|
Thyroidectomy, RAI therapy, and radical nephrectomy
|
Conclusion
Renal metastasis from HCTC is a rare occurrence which tends to be overlooked and usually
occurs in the setting of extensive multiple organ metastases.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form the patient(s) has/have given his/her/their consent for his/her/their
images and other clinical information to be reported in the journal. The patients
understand that their names and initials will not be published and due efforts will
be made to conceal their identity, but anonymity cannot be guaranteed.
