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Leu-7 immunoreactivity in cytologic specimens of thyroid lesions, with emphasis on follicular neoplasms
M L Ostrowski1, R W Brown, T M Wheeler
1Department of Pathology, Baylor College of Medicine, Houston, TX, USA.
Insights
The anti-Leu-7 antibody shows reactivity in both benign and malignant thyroid follicular neoplasms. This study found it is not a specific marker for distinguishing follicular carcinoma from follicular adenoma in cytologic specimens.
Area of Science:
- Immunohistochemistry
- Cytopathology
- Endocrinology
Background:
- The anti-Leu-7 antibody (HNK-1, CD 57) is a marker for natural killer lymphocytes.
- Previous studies indicated strong immunoreactivity with thyroid carcinomas but weak with benign lesions.
Purpose of the Study:
- To evaluate the utility of the anti-Leu-7 antibody as a specific marker for malignancy in thyroid cytologic specimens, particularly follicular neoplasms.
Main Methods:
- Analysis of fine-needle aspiration biopsy specimens from 44 thyroid lesions.
- Immunohistochemical staining using the anti-Leu-7 antibody.
- Comparison of immunoreactivity patterns in follicular carcinomas, follicular adenomas, adenomatous nodules, papillary carcinomas, and Hashimoto's thyroiditis.
Main Results:
- All ten follicular carcinomas showed anti-Leu-7 immunoreactivity (9/10 moderate to strong).
- Six of fourteen follicular adenomas also exhibited similar immunoreactivity.
- Other lesions showed patterns consistent with prior research.
Conclusions:
- The anti-Leu-7 antibody is not a specific marker for malignancy in the cytologic assessment of thyroid follicular neoplasms.
- Distinguishing between follicular carcinoma and follicular adenoma using this antibody alone is unreliable.
Abstract:
Anti-Leu-7 (HNK-1, CD 57) antibody, a marker for natural killer lymphocytes, was employed by Ghali et al. (Hum Pathol 1992;23: 21-25) to study surgically resected formalin-fixed, paraffin-embedded thyroid lesions. They demonstrated strong immunoreactivity of this antibody with thyroid carcinomas, both follicular and papillary, and only occasional weak immunoreactivity with colloid goiters and follicular adenomas. We studied cytologic specimens (primarily fine-needle aspiration biopsy specimens) from 44 thyroid lesions, including 10 follicular carcinomas, 14 follicular adenomas, seven adenomatous nodules, six papillary carcinomas, and seven cases of Hashimoto's thyroiditis. All follicular carcinomas exhibited immunoreactivity to anti-Leu-7 antibody, usually of a moderate to strong degree (9/10); however, six of 14 follicular adenomas yielded similar results. The patterns of immunoreactivity in the other lesions were similar to those previously described (Ghali et al., Hum Pathol 1992;23:21-25). It does not appear that anti-Leu-7 antibody can be used as a specific marker of malignancy in the cytologic assessment of follicular neoplasms of the thyroid.