CASTLE Thyroid Tumor: A Case Report and Literature Review

Abstract

Carcinoma showing thymus-like differentiation is a rare tumor of the thyroid gland, which is structurally similar to thymic tissue. Overall, it has a favorable prognosis. Radiotherapy has been shown to be an effective local treatment, but there have been reports of distant recurrence. It has been suggested that adding chemotherapy may decrease the risk of recurrence. Here, we present a case report of a patient with a large tumor and extrathyroidal extension. The patient was treated with surgery, radiotherapy, and cisplatin with acceptable toxicity. The patient is free of locally recurrent or distant disease at 3 years.

Keywords: CASTLE; case report; radiation therapy; thyroid carcinoma; thyroid tumor.

Figure 1

The tumor cells are arranged in broad, pushing, smooth-bordered islands abutted against a lymphocyte rich stroma and seen in 10× (Figure 1) and 20× (Figure 2).

Figure 2

Figure 1 magnification. The asterisks highlights the lobules of tumor in the images. These are surrounded by lymphocytes and plasma cells, as indicated by the arrow.

Figure 3

The neoplastic cells are strongly immunoreactive for pancytokeratin. Lymphocytes are negative.

Figure 4

The tumor cell shows strong immunoreactivity to p63. Lymphocytes lack reactivity.

Figure 5

Tumors cells that demonstrate strong positivity to CD5, also marking background lymphocytes.

Figure 6

Coronal section of radiotherapy plan showing 60 Gy dose line in green and boost volume in red.