J Korean Endocr Soc.  2008 Oct;23(5):327-331. 10.3803/jkes.2008.23.5.327.

A Case of Hyalinizing Trabecular Tumor of the Thyroid Gland Misdiagnosed as Medullary Carcinoma at Cytologic Examination

• Han JJ
• Lee YJ
• Choi MC
• Kwon M
• Chon S
• Lee J

• KMID: 1479225
• DOI: http://doi.org/10.3803/jkes.2008.23.5.327

Abstract

A hyalinizing trabecular tumor (HTT) is a rare benign thyroid tumor that can present as a solitary thyroid nodule, a prominent nodule in a multinodular goiter, or as an incidental finding within a thyroidectomy specimen. The clinical importance of this entity is that it is frequently misdiagnosed as papillary carcinoma or medullary carcinoma on fine-needle aspiration cytology or histopathologic examination. The cytology of HTT is characterized by hypercellularity, nuclear grooves, nuclear pseudoinclusions, and powdery chromatin of the tumor cells, which is frequently seen in papillary carcinomas. The histologic findings of the tumor show polygonal and spindle cells arranged in a trabecular growth pattern with the presence of a variable hyalinized stroma. Calcitonin and other neuroendocrine markers can be used to differentiate HTT from medullary carcinoma. MIB-1, galectin-3, or other cytokeratin markers help to exclude papillary carcinoma. We report a patient with a thyroid tumor misdiagnosed as a medullary carcinoma on fine-needle aspiration and finally diagnosed as HTT after total thyroidectomy and immunohistochemical examination.

Keyword

fine needle aspiration; hyalinizing trabecular tumor; thyroid nodules

MeSH Terms

Biopsy, Fine-Needle
Calcitonin
Carcinoma, Medullary
Carcinoma, Papillary
Chromatin
Galectin 3
Goiter
Humans
Hyalin
Incidental Findings
Keratins
Thyroid Gland
Thyroid Nodule
Thyroidectomy
Calcitonin
Chromatin
Galectin 3
Keratins

Figure

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  Fig. 1 0.8 × 0.7 cm and 1.6 × 0.7 cm sized isoechoic nodules were noted at right and left thyroid.

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  Fig. 2 Specimen form fine needle aspiration show atypical spindle cells having elongate nuclei and pseudoinclusions.

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  Fig. 3 After total thyroidectomy, cut surface of surgical specimen shows three rather well defined nodules, measuring 1.7 × 1.3 cm, 1 × 0.8 cm and 1.0 × 1.0 cm in size, respectively.

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  Fig. 4 H&E stain, ×400; Proliferation of spindle and ovoid cells with granular ampophilic cytoplasm and medium sized nucleus, separated by vascular stroma, hyalinized collagen and amyloid, arranged in follicular and trabecular pattern.

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  Fig. 5 Immunohistochemical stain with calcitonin, thyroglubuilin were both positive. But, chromogranin and synaptophysin were both negative.

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  Fig. 6 Immunohistochemical stain with MIB-1 (Ki-67) was positive along with the cell membrane.

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  Fig. 7 Galectin stain was positive.

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