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SOLITARY METASTASIS OF RENAL CLEAR CELL
CARCINOMA TO HÜRTHLE CELL ADENOMA OF
THYROID GLAND: REPORT OF A CASE
RITA PASSANTINO - LORENZO MARASA’
Department of Pathology, A.R.N.A.S. Civico, Palermo
INTRODUCTION
 Metastases to the thyroid gland are a common finding at
autopsy in patients who died of malignancy and are
often misdiagnosed as primary thyroid neoplasms
clinically.
 Metastatic Renal Cell Carcinoma (RCC) to the thyroid
gland is a rare occurence but must be considered in the
differential diagnosis of Clear Cell Tumours (CCT) of the
thyroid gland to prevent misclassification, potentially
resulting in inappropriate clinical management.
 We present a patient with a rare, unusual case of RCC
metastatic to a Hürthle cell adenoma of the thyroid
gland.
CASE REPORT
 The patient was a 77-year-old sicilian woman who was
referred to our department after a thyroid tumour was
identified in February 2008.
 She had a history of RCC of the left kidney, which had
been resected 3 years previously.
 Ultrasound
sonography
demonstrated
a
welldemarcated hypoechoic mass which measured 3.5 cm
in greatest diameter and occupied the left lobe.
 A total thyroidectomy was performed on March 2008.
 A solitary, well circumscribed, encapsulated, bright
yellow to reddish-tan mass with hemorrhage and
degenerative changes, which measured 3.5 cm in
greatest diameter and occupied the left lobe of the
thyroid gland.
HISTOLOGICAL EXAMINATION
 A Hürthle cell adenoma containing large clusters of
cells with abundant clear cytoplasm and round
nuclei.
 The
predominant
histologic
pattern
was
characterized by the presence of small nests, cords
and “pseudofollicles” made up of neoplastic cells
separated by a prominent vascular stroma with
sinusoidal-type blood vessels and intraluminal fresh
hemorrhage.
 Metastatic cells contained variable amounts of PASpositive material which was indicative of glycogen in
the cytoplasm of the clear cells.
 Metastasis showed morphological characteristics
identical to the RCC resected 3 years previously.
IMMUNOHISTOCHEMICAL EXAMINATION
 Specific markers of Hürthle cell adenoma such as
thyroglobulin, CK14, CEA, S-100 protein and HMB-45
stained negatively in the clear neoplastic cells.
 Specific markers of RCC such as EMA and vimentin
stained positively.
THYROGLOBULIN
EMA
VIMENTIN
CONCLUSIONS
 The thyroid gland is a rare site of tumour metastasis.
 RCC is one of the more common neoplasm to
metastasize to the thyroid gland (<0.1%).
 Metastatic RCC to a thyroid neoplasm is extremely rare,
with only three reports found in the international
literature.
 The possibility of metastatic RCC should always be
taken under consideration, especially when nests of
clear cells are seen infiltrating into the thyroid
parenchyma or neoplasm.
CONCLUSIONS
 Our report shows that the architectural, cytologic, histologic, histochemical, and immunohistochemical features are sufficiently distinctive to allow differentation
of a primary thyroid epithelial neoplasm with clear cell
changes from metastatic RCC.
 This distinction is important to correctly manage the
patient.
 Surgical treatment is recommended as the patient may
enjoy a prolonged survival.
MAIN REFERENCE:
Qian L. Renal cell carcinoma metastatic to Hürthle cell
adenoma of thyroid. Ann Diagn Pathol. 2004 Oct; 8(5):
305-8.