Abstract
BackgroundAnaplastic thyroid carcinoma (ATC) is a rare malignant tumor. In addition to the main ATC type with classical histopathological features, the other morphological types of ATC include paucicellular variant, angiomatoid, lymphoepithelioma-like, and small-cell variant. However, an ATC variant with a chondrosarcomatous component has not been reported to date.Case presentationComputed tomography imaging of a 63-year-old male with a 2-month history of a cervical mass revealed a 4.5-cm lesion with heterogeneous enhancement in the left thyroid lobe and two smooth and homogeneous nodules in the right thyroid lobe. The patient underwent total thyroidectomy and cervical lymph node resection. Histologically, the tumor boundary in the left lobe was clear, with a few mitotically active, spindle sarcoma-like tumor cells observed in some areas. Immunohistochemically, these spindle cells were positive for vimentin and negative for cytokeratin, paired box-8, epithelial membrane antigen, calcitonin, thyroglobulin, and thyroid transcription factor-1. In other areas, abundant cartilage matrix production and irregularly shaped lobules of cartilage, often separated by fibrous bands, were observed. The chondrocytes appeared mildly/moderately atypical and contained enlarged, hyperchromatic nucleoli. One of the two nodules in the right thyroid lobe had a clear boundary and comprised some bland spindle cells in a prominently collagenous stroma with clear boundaries. The other nodule in the right thyroid lobe was completely enclosed within a thin, fibrous capsule and exhibited normofollicular and microfollicular architecture. The patient received adjuvant radiotherapy after the surgery and was free of any local or regional recurrence or distant metastases at the 8-month follow-up evaluation.ConclusionsThis unusual case of ATC with chondrosarcomatous differentiation is an important addition to the morphology spectrum of ATC types.
Highlights
Anaplastic thyroid carcinoma (ATC) is a rare malignant tumor
This unusual case of ATC with chondrosarcomatous differentiation is an important addition to the morphology spectrum of ATC types
The spindle tumor cells in both thyroid lobes were positive for vimentin (Fig. 3a) but negative for cytokeratin (Fig. 3b and c) and epithelial membrane antigen
Summary
Anaplastic thyroid carcinoma (ATC) is a rare malignant tumor. In addition to the main ATC type with classical histopathological features, the other morphological types of ATC include paucicellular variant, angiomatoid, lymphoepithelioma-like, and small-cell variant. The diagnosis can be more challenging in cases where ATC does not exhibit a typical morphology, especially when the malignant spindle cells do not express cytokeratin. We report an unusual case of ATC containing a chondrosarcomatous component. The majority of the tumor in the left thyroid lobe comprised low-grade hyaline-type cartilage, and some spindle cells were observed around the Immunohistochemical findings Table 1 shows the summary of immunohistochemical findings.
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