International Journal of Urology

(2002)

9,

656–658

Case Report

Blackwell Science, LtdOxford, UKIJU

International Journal of Urology0919-81722002 Blackwell Science Asia Pty Ltd

911November 2002537

Renal metastasis of thyroid carcinomaK Abe et al.

10.1046/j.0919-8172.2002.00537.xCase Report656658BEES SGML

Correspondence: Kazuhiro Abe

MD

, 3-25-8 Nishishinbashi,Minato-ku,Tokyo 105-8461, Japan.Email: ju-kazuo@sb4.so.net.jp

Received 12 December 2001; accepted 13 May 2002.

Renal metastasis of thyroid carcinoma

KAZUHIRO ABE,

1

TARO HASEGAWA,

1

SHOICHI ONODERA,

1

YUKIHIKO OISHI

1

AND MASAFUMI SUZUKI

2

Departments of

1

Urology and

2

Pathology, Jikei University School of Medicine, Tokyo, Japan

Abstract

We report here the sixth known case of metastatic renal tumor of thyroid carcinoma. In 1999, a 37-year-old man was referred to us with a left renal mass found incidentally by ultrasound during anannual check-up. Computed tomography (CT) revealed a well-defined, hyperdense mass 3 cm indiameter in the middle of the left kidney. Left radical nephrectomy was performed under the preop-erative diagnosis of renal cell carcinoma. Histologically, the tumor was metastatic of typical papillarythyroid carcinoma.

Key words

kidney, metastasis, thyroid carcinoma.

Introduction

In general, well-differentiated thyroid carcinoma isan indolent disease. However, a small subset of well-differentiated thyroid carcinoma develop distantmetastases. Only five patients with metastatic renaltumor of thyroid carcinoma have been reported previ-ously.

1–5

We report here the sixth known case of renalmetastasis of papillary thyroid carcinoma.

Case report

A 37-year-old man with a left renal mass incidentallyfound during an annual check-up was referred to us inSeptember 1999. No abdominal mass or lymphonodewas palpable in the physical findings. In addition, noabnormal value including IAP was found in the labora-tory findings. Computed tomography (CT) scan con-firmed a well-defined, hyperdense mass with a diameterof 3 cm in the middle of the left kidney (Fig. 1). Leftrenal angiography showed no vascularity in the left renalmass. From these results, the preoperative diagnosis wasrenal cell carcinoma (RCC) and left radical nephrec-tomy was performed. Cervical CT scan revealed irreg-

ular thyroid swelling (Fig. 2). Histologically, the tumorwas a metastatic papillary thyroid carcinoma (Fig. 3).The patient then underwent a total thyroidectomy,demonstrating an encapsulated lesion with occasionaltumor cells invading the capsula, and cervical lymphmetastasis. The patient received

131

I ablation therapypostoperatively, and he is now alive, but has lungmetastasis.

Discussion

Metastatic renal tumor of thyroid cancer is rare. Onlyfive cases have been previously reported,

1–5

this casebeing the sixth. Among the six cases, four were follic-ular and two were papillary carcinomas (Table 1). Allexcept our case occurred in female patients. Two of thesix patients had bilateral kidney metastasis and three ofthe six cases had a second site of metastasis. The periodof interval between the diagnosis of thyroid cancer andthe diagnosis of renal metastasis was long (mean,16.6 years; range, 3–37 years). This finding is consistentwith the slow course of well-differentiated thyroid can-cer. According to the literature, 1.4–6% of well differ-entiated thyroid carcinoma patients developed distantmetastasis.

6

The most common sites of metastasis werebone (43%), lung (40%) and mediastinum (32%). Theprognosis of metastatic well-differentiated thyroid can-cer is favorable compared to that of other carcinomas.Wood

et al

. found the 5-year survival period of well-dif-ferentiated thyroid carcinoma patients with resectablemetastatic lesions was 67%.

6

Renal metastasis of thyroid carcinoma 657

In general, metastatic renal tumors are multiple,bilateral and accompanied by metastatic disease else-where. Honda

et al

. reported that CT analysis of meta-static renal tumors yields a high sensitivity fordistinction from RCC. They reported that metastaticrenal tumors are less exophytic, multiple and small renallesions with or without a wedge-shape appearance.

7

Differentiated thyroid carcinoma is generally consid-ered an indolent disease. We, therefore, believe surgicaltreatment of resectable metastasis may provide pro-longed prognosis.

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Fig. 1

Computed tomography scan revealed left renalmass heterogeneously enhanced.

Fig. 2

Cervical computed tomography scan revealed theirregular thyroid swelling.

Fig. 3

Histologic section of left renal mass showing met-astatic typical papillary thyroid carcinoma.

Table 1

Reported cases of metastatic renal tumor of thyroid cancer

Age Sex Side Interval (years)† Histology Metastatic site‡

47 Female Bilateral 3 Follicular —52 Female Left 22 Papillary Liver, rectus muscle49 Female Bilateral 18 Follicular —66 Female Left 37 Follicular Lung, mediastinum liver72 Female Right 3 Follicular Liver37 Male Left — Papillary Lymph nodes

†Interval between diagnosis of the thyroid cancer and renal metastasis; ‡excluding kidney.

658 K Abe

et al

.

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