We have previously shown that necrotic
tumors retain their immunoreactivity for a range of
cytokeratin antibodies. Some thyroid
tumors undergo extensive
necrosis after fine-needle aspiration (FNA) procedures. We evaluated the sensitivity of
antibodies on necrotic thyroid
tumors by examining a series of thyroid
tumors consisting of 10 Hurthle cell
neoplasms, 8
carcinomas, and 2
follicular adenomas (12 with post-FNA
necrosis). These were stained with
antibodies to AE1/3, PANCK,
thyroglobulin and S100. Four of the cases of
papillary carcinoma were also stained with
antibodies to CK19. As a control for the specificity of
thyroglobulin immunoreactivity in necrotic tissue, we also stained 11 nonthyroid
tumors with extensive
necrosis (7
carcinomas, 1
lymphoma, 2
melanomas, 1
sarcoma) for
thyroglobulin. Six of 8
thyroid carcinomas were positive for AE1/3 and PANCK; AE1/3 reactivity was retained in necrotic areas of 4 of 6. AE 1/3 was positive in necrotic portions of 5 of 10 Hurthle cell lesions, whereas PANCKwas negative in all but 1.
Thyroglobulin reactivity was present in 18 of 20 cases, and was preserved in necrotic portions of 5 of 6
carcinomas, as well
as 8 of 10 Hurthle cell
neoplasms. S100 cytoplasmic reactivity was present in 4 Hurthle cell
neoplasms and 1
papillary carcinoma; this staining was lost in necrotic areas. No staining by
thyroglobulin was observed in the viable or necrotic areas of nonthyroid
neoplasms. The preservation of
cytokeratin reactivity, measured by AE1/3, in
thyroid neoplasms is a diagnostically useful feature in spontaneous and post-FNA
infarction. PANCK is not a well-preserved marker in necrotic thyroid tissue. This difference may be due to detection of
keratin 19 by AE1/3.
Thyroglobulin is preserved in some necrotic
thyroid carcinomas and in Hurthle cell lesions. Preservation of
thyroglobulin reactivity in necrotic tissue is specific in that no staining was observed in nonthyroid
neoplasms. These results suggest that
thyroglobulin is useful in demonstrating thyroid lineage of both primary and metastatic necrotic
tumor masses.