SOLITARY METASTASIS OF RENAL CLEAR CELL SOLITARY METASTASIS OF RENAL CLEAR CELL CARCINOMA TO HCARCINOMA TO HÜRTHLE CELL ADENOMA OF ÜRTHLE CELL ADENOMA OF

THYROID GLAND: REPORT OF A CASETHYROID GLAND: REPORT OF A CASE

SOLITARY METASTASIS OF RENAL CLEAR CELL SOLITARY METASTASIS OF RENAL CLEAR CELL CARCINOMA TO HCARCINOMA TO HÜRTHLE CELL ADENOMA OF ÜRTHLE CELL ADENOMA OF

THYROID GLAND: REPORT OF A CASETHYROID GLAND: REPORT OF A CASE

RITA PASSANTINO - LORENZO MARASA’RITA PASSANTINO - LORENZO MARASA’

Department of Pathology, A.R.N.A.S. Civico, PalermoDepartment of Pathology, A.R.N.A.S. Civico, Palermo

RITA PASSANTINO - LORENZO MARASA’RITA PASSANTINO - LORENZO MARASA’

Department of Pathology, A.R.N.A.S. Civico, PalermoDepartment of Pathology, A.R.N.A.S. Civico, Palermo

INTRODUCTIONINTRODUCTIONINTRODUCTIONINTRODUCTION

Metastases to the thyroid gland are a common finding at Metastases to the thyroid gland are a common finding at autopsy in patients who died of malignancy and are autopsy in patients who died of malignancy and are often misdiagnosed as primary thyroid neoplasms often misdiagnosed as primary thyroid neoplasms clinically. clinically.

Metastatic Renal Cell Carcinoma (RCC) to the thyroid Metastatic Renal Cell Carcinoma (RCC) to the thyroid gland is a rare occurence but must be considered in the gland is a rare occurence but must be considered in the differential diagnosis of Clear Cell Tumours (CCT) of the differential diagnosis of Clear Cell Tumours (CCT) of the thyroid gland to prevent misclassification, potentially thyroid gland to prevent misclassification, potentially resulting in inappropriate clinical management. resulting in inappropriate clinical management.

We present a patient with a rare, unusual case of RCC We present a patient with a rare, unusual case of RCC metastatic to a Hmetastatic to a Hürthle cell adenoma of the thyroid ürthle cell adenoma of the thyroid gland.gland.

Metastases to the thyroid gland are a common finding at Metastases to the thyroid gland are a common finding at autopsy in patients who died of malignancy and are autopsy in patients who died of malignancy and are often misdiagnosed as primary thyroid neoplasms often misdiagnosed as primary thyroid neoplasms clinically. clinically.

Metastatic Renal Cell Carcinoma (RCC) to the thyroid Metastatic Renal Cell Carcinoma (RCC) to the thyroid gland is a rare occurence but must be considered in the gland is a rare occurence but must be considered in the differential diagnosis of Clear Cell Tumours (CCT) of the differential diagnosis of Clear Cell Tumours (CCT) of the thyroid gland to prevent misclassification, potentially thyroid gland to prevent misclassification, potentially resulting in inappropriate clinical management. resulting in inappropriate clinical management.

We present a patient with a rare, unusual case of RCC We present a patient with a rare, unusual case of RCC metastatic to a Hmetastatic to a Hürthle cell adenoma of the thyroid ürthle cell adenoma of the thyroid gland.gland.

CASE REPORT CASE REPORT CASE REPORT CASE REPORT

The patient was a 77-year-old sicilian woman who was The patient was a 77-year-old sicilian woman who was referred to our department after a thyroid tumour was referred to our department after a thyroid tumour was identified in February 2008.identified in February 2008.

She had a history of RCC of the left kidney, which had She had a history of RCC of the left kidney, which had

been resected 3 years previously.been resected 3 years previously. Ultrasound sonography demonstrated a well-Ultrasound sonography demonstrated a well-

demarcated hypoechoic mass which measured 3.5 cm demarcated hypoechoic mass which measured 3.5 cm in greatest diameter and occupied the left lobe.in greatest diameter and occupied the left lobe.

A total thyroidectomy was performed on March 2008. A total thyroidectomy was performed on March 2008.

A solitary, well circumscribed, encapsulated, bright A solitary, well circumscribed, encapsulated, bright yellow to reddish-tan mass with hemorrhage and yellow to reddish-tan mass with hemorrhage and degenerative changes, which measured 3.5 cm in degenerative changes, which measured 3.5 cm in greatest diameter and occupied the left lobe of the greatest diameter and occupied the left lobe of the thyroid gland. thyroid gland.

The patient was a 77-year-old sicilian woman who was The patient was a 77-year-old sicilian woman who was referred to our department after a thyroid tumour was referred to our department after a thyroid tumour was identified in February 2008.identified in February 2008.

She had a history of RCC of the left kidney, which had She had a history of RCC of the left kidney, which had

been resected 3 years previously.been resected 3 years previously. Ultrasound sonography demonstrated a well-Ultrasound sonography demonstrated a well-

demarcated hypoechoic mass which measured 3.5 cm demarcated hypoechoic mass which measured 3.5 cm in greatest diameter and occupied the left lobe.in greatest diameter and occupied the left lobe.

A total thyroidectomy was performed on March 2008. A total thyroidectomy was performed on March 2008.

A solitary, well circumscribed, encapsulated, bright A solitary, well circumscribed, encapsulated, bright yellow to reddish-tan mass with hemorrhage and yellow to reddish-tan mass with hemorrhage and degenerative changes, which measured 3.5 cm in degenerative changes, which measured 3.5 cm in greatest diameter and occupied the left lobe of the greatest diameter and occupied the left lobe of the thyroid gland. thyroid gland.

HISTOLOGICAL EXAMINATIONHISTOLOGICAL EXAMINATION HISTOLOGICAL EXAMINATIONHISTOLOGICAL EXAMINATION

A HA Hürthle cell adenoma containing large clusters of ürthle cell adenoma containing large clusters of cells with abundant clear cytoplasm and round nuclei. cells with abundant clear cytoplasm and round nuclei.

The predominant histologic pattern was characterized The predominant histologic pattern was characterized by the presence of small nests, cords and by the presence of small nests, cords and “pseudofollicles” made up of neoplastic cells separated “pseudofollicles” made up of neoplastic cells separated by a prominent vascular stroma with sinusoidal-type by a prominent vascular stroma with sinusoidal-type blood vessels and intraluminal fresh hemorrhage.blood vessels and intraluminal fresh hemorrhage.

Metastatic cells contained variable amounts of PAS-Metastatic cells contained variable amounts of PAS-positive material which was indicative of glycogen in positive material which was indicative of glycogen in the cytoplasm of the clear cells.the cytoplasm of the clear cells.

Metastasis showed morphological characteristics Metastasis showed morphological characteristics identical to the RCC resected 3 years previously. identical to the RCC resected 3 years previously.

A HA Hürthle cell adenoma containing large clusters of ürthle cell adenoma containing large clusters of cells with abundant clear cytoplasm and round nuclei. cells with abundant clear cytoplasm and round nuclei.

The predominant histologic pattern was characterized The predominant histologic pattern was characterized by the presence of small nests, cords and by the presence of small nests, cords and “pseudofollicles” made up of neoplastic cells separated “pseudofollicles” made up of neoplastic cells separated by a prominent vascular stroma with sinusoidal-type by a prominent vascular stroma with sinusoidal-type blood vessels and intraluminal fresh hemorrhage.blood vessels and intraluminal fresh hemorrhage.

Metastatic cells contained variable amounts of PAS-Metastatic cells contained variable amounts of PAS-positive material which was indicative of glycogen in positive material which was indicative of glycogen in the cytoplasm of the clear cells.the cytoplasm of the clear cells.

Metastasis showed morphological characteristics Metastasis showed morphological characteristics identical to the RCC resected 3 years previously. identical to the RCC resected 3 years previously.

IMMUNOHISTOCHEMICAL EXAMINATION IMMUNOHISTOCHEMICAL EXAMINATION IMMUNOHISTOCHEMICAL EXAMINATION IMMUNOHISTOCHEMICAL EXAMINATION

Specific markers of HSpecific markers of Hürthle cell adenoma such as ürthle cell adenoma such as thyroglobulin, CK14, CEA, S-100 protein and HMB-45 thyroglobulin, CK14, CEA, S-100 protein and HMB-45 stained negatively in the clear neoplastic cells.stained negatively in the clear neoplastic cells.

Specific markers of RCC such as EMA and vimentin Specific markers of RCC such as EMA and vimentin stained positively. stained positively.

Specific markers of HSpecific markers of Hürthle cell adenoma such as ürthle cell adenoma such as thyroglobulin, CK14, CEA, S-100 protein and HMB-45 thyroglobulin, CK14, CEA, S-100 protein and HMB-45 stained negatively in the clear neoplastic cells.stained negatively in the clear neoplastic cells.

Specific markers of RCC such as EMA and vimentin Specific markers of RCC such as EMA and vimentin stained positively. stained positively.

THYROGLOBULINTHYROGLOBULIN VIMENTINVIMENTINEMAEMA

CONCLUSIONSCONCLUSIONSCONCLUSIONSCONCLUSIONS

The thyroid gland is a rare site of tumour metastasis.The thyroid gland is a rare site of tumour metastasis.

RCC is one of the more common neoplasm to RCC is one of the more common neoplasm to metastasize to the thyroid gland (<0.1%).metastasize to the thyroid gland (<0.1%).

Metastatic RCC to a thyroid neoplasm is extremely rare, Metastatic RCC to a thyroid neoplasm is extremely rare, with only three reports found in the international with only three reports found in the international literature.literature.

The possibility of metastatic RCC should always be The possibility of metastatic RCC should always be taken under consideration, especially when nests of taken under consideration, especially when nests of clear cells are seen infiltrating into the thyroid clear cells are seen infiltrating into the thyroid parenchyma or neoplasm. parenchyma or neoplasm.

The thyroid gland is a rare site of tumour metastasis.The thyroid gland is a rare site of tumour metastasis.

RCC is one of the more common neoplasm to RCC is one of the more common neoplasm to metastasize to the thyroid gland (<0.1%).metastasize to the thyroid gland (<0.1%).

Metastatic RCC to a thyroid neoplasm is extremely rare, Metastatic RCC to a thyroid neoplasm is extremely rare, with only three reports found in the international with only three reports found in the international literature.literature.

The possibility of metastatic RCC should always be The possibility of metastatic RCC should always be taken under consideration, especially when nests of taken under consideration, especially when nests of clear cells are seen infiltrating into the thyroid clear cells are seen infiltrating into the thyroid parenchyma or neoplasm. parenchyma or neoplasm.

CONCLUSIONSCONCLUSIONSCONCLUSIONSCONCLUSIONS

Our report shows that the architectural, cytologic, hi-stologic, Our report shows that the architectural, cytologic, hi-stologic, histochemical, and immunohistochemical fea-tures are histochemical, and immunohistochemical fea-tures are sufficiently distinctive to allow differentation of a primary sufficiently distinctive to allow differentation of a primary thyroid epithelial neoplasm with clear cell changes from thyroid epithelial neoplasm with clear cell changes from metastatic RCC.metastatic RCC.

This distinction is important to correctly manage the patient. This distinction is important to correctly manage the patient.

Surgical treatment is recommended as the patient may enjoy Surgical treatment is recommended as the patient may enjoy a prolonged survival.a prolonged survival.

MAIN REFERENCE:MAIN REFERENCE: Qian L. Renal cell carcinoma metastatic to Hürthle cell Qian L. Renal cell carcinoma metastatic to Hürthle cell

adenoma of thyroid. adenoma of thyroid. Ann Diagn Pathol. Ann Diagn Pathol. 2004 Oct; 8(5): 305-8. 2004 Oct; 8(5): 305-8.

Our report shows that the architectural, cytologic, hi-stologic, Our report shows that the architectural, cytologic, hi-stologic, histochemical, and immunohistochemical fea-tures are histochemical, and immunohistochemical fea-tures are sufficiently distinctive to allow differentation of a primary sufficiently distinctive to allow differentation of a primary thyroid epithelial neoplasm with clear cell changes from thyroid epithelial neoplasm with clear cell changes from metastatic RCC.metastatic RCC.

This distinction is important to correctly manage the patient. This distinction is important to correctly manage the patient.

Surgical treatment is recommended as the patient may enjoy Surgical treatment is recommended as the patient may enjoy a prolonged survival.a prolonged survival.

MAIN REFERENCE:MAIN REFERENCE: Qian L. Renal cell carcinoma metastatic to Hürthle cell Qian L. Renal cell carcinoma metastatic to Hürthle cell

adenoma of thyroid. adenoma of thyroid. Ann Diagn Pathol. Ann Diagn Pathol. 2004 Oct; 8(5): 305-8. 2004 Oct; 8(5): 305-8.