Contributed by Siobhan O'Connor, MD, Leon Barnes, MD and Karen Schoedel, MD
Published on line in February 2006
The patient is a 65 year old man who presented for fine needle aspiration of the thyroid due to heterogeneous enlargement of both lobes of the gland.
Past medical history is significant for renal cell carcinoma, clear cell type, confined to the left kidney status post radical left nephrectomy in 1994. Adenocarcinoma of the prostate was diagnosed in 1999 and treated with radical prostatectomy. Bilateral lymph node dissection demonstrated no metastases.
Enlargement of the left lobe of the thyroid to 2.4 x 3.3 cm was noted incidentally on a surveillance CT scan. A subsequent fine needle aspiration showed scant cellularity, but was negative for malignant cells, and occasional macrophages were identified. Ultrasound of the thyroid showed multinodular goiter with a dominant nodule in each lobe. Heterogeneous enlargement of the thyroid was again noted by CT scan. There was no laboratory evidence of thyroid dysfunction.
The ultrasound-guided fine needle aspiration revealed atypical cells with abundant, focally vacuolated cytoplasm and prominent nucleoli. Images 1 (Diff-Quick) and 2 (Papanicolaou) show these features, which appear more distinct with Diff-Quick staining. The sample from the right thyroid also contained several clusters of epithelial cells associated with lymphocytes. Hürthle-like changes and presence of lymphocytes were suggestive of lymphocytic thyroiditis. However, given the patient's history, renal cell carcinoma could not be excluded. Images 3 and 4 demonstrate the enlarged (right greater than left), multinodular thyroid lobes seen by ultrasound. Findings on ultrasound were interpreted as multinodular thyroid goiter with a 3.3 cm dominant heterogeneous nodule in the mid to lower pole of the left lobe.
FINE NEEDLE ASPIRATION:
The patient underwent total thyroidectomy on 11/15/05. Image 5 shows the 56.56 gram multinodular thyroid, right lobe 5.8 x 5.5 x 3.0 cm and left lobe 4.7 x 3.2 x 2.6 cm. On cut section, the thyroid was almost completely replaced by a fleshy, yellow/tan, septated and hemorrhagic tumor (Images 5, 6 and 7).
Scrape preparation H&E stained sections performed at time of gross dissection show a bloody background with clusters of atypical cells. In images 8 and 9, the nuclei are somewhat pleomorphic with prominent nucleoli, and there is abundant cytoplasm which appears predominantly granular, but vacuoles can be identified.
At low power, histologic sections reveal tumor nodules divided by fibrous septae. A pseudocapsule of fibrous tissue is present at the periphery, separating the tumor mass from adjacent compressed thyroid tissue (image 10). At higher power, some cells form solid sheets while others are arranged in an alveolar pattern with thin connective tissue strands between the tumor nests. The mass is highly vascular with numerous thin-walled vessels and extravasation of red blood cells. It is composed of clear cells with sharply outlined borders and oval nuclei with mild to moderate pleomorphism and visible nucleoli (images 11 and 12).
The tumor shows diffuse, strong staining with CD10 (image 13) and vimentin (image 14). Diffuse, but lighter staining was achieved with renal cell carcinoma immunostain (image 15) and patchy strong staining with epithelial membrane antigen (image 16).
Tthe patient is healing well from his thyroidectomy, and, by CT scan, has a stable nodule in the upper lobe of the left lung and one in the right adrenal gland. These nodules have not been evaluated histologically, but are presumed to represent stable metastatic disease.