Ectopic Cervical Thyroid Tissue Affected by Fibrosing Hashimoto’s Thyroiditis Mimicking Multifocal Metastatic Papillary Thyroid Carcinoma—A Hard Lesson Learnt from an Unusual Case

Abstract

We describe a case of ectopic cervical thyroid tissue which was involved by fibrosing Hashimoto's thyroiditis and which mimicked metastatic papillary thyroid carcinoma both on fine needle aspiration cytology and biopsy. The patient underwent total thyroidectomy which revealed fibrosing Hashimoto's thyroiditis, but no carcinoma. The entire thyroidectomy specimen was submitted for histopathological assessment. Even in the resected thyroidectomy specimen, there were cytological changes that were strongly reminiscent of papillary thyroid carcinoma. However, interpreted in the correct clinico-pathological context, these cytological alterations were deemed to be reactive secondary to the fibro-inflammatory process.

“Parasitic” or sequestered thyroid nodule

“…4 Tan HM, et al reported a 52-year-old female with hypothyroidism and developed an anterior neck (1.0 cm) nodule, which was distinctly separate from the thyroid gland. 5 Aspirate biopsy showed predominance of small lymphocytes, small crowded groups of atypical epithelial cells with large round to ovoid nuclei, and some nuclear grooves; the diagnostic hypotheses were lymph node metastatic carcinoma or lymphocytic thyroiditis. 5 As an excision biopsy was also suspected of metastatic carcinoma, a total thyroidectomy and neck dissection were performed, but fibrosing Hashimoto thyroiditis was confirmed.…”

“…5 Aspirate biopsy showed predominance of small lymphocytes, small crowded groups of atypical epithelial cells with large round to ovoid nuclei, and some nuclear grooves; the diagnostic hypotheses were lymph node metastatic carcinoma or lymphocytic thyroiditis. 5 As an excision biopsy was also suspected of metastatic carcinoma, a total thyroidectomy and neck dissection were performed, but fibrosing Hashimoto thyroiditis was confirmed. 5 The authors emphasized the procedures to avoid the misdiagnoses between Hashimoto thyroiditis and thyroid cancer, aiming to prevent the unnecessary surgical interventions.…”

“…Parasitic (or sequestered) is a peripheral thyroid nodule anatomically separate from the gland, or an implant of detached thyroid tissue from a Hashimoto thyroiditis or goiter. [1][2][3][4][5] They often have a perithyroidal site, but may appear in lateral neck or in mediastinum; [1][2][3][4][5] and the mean age of the patients is 51 (15-83) years, with a female/ male ratio of 4:1. 1 Besides thyroid embryogenic changes, trauma or surgery, the sequestered tissue has been associated with a mechanical action of neck muscles in cases of nodular colloid goiter.…”

“…1,2 The histopathologic aspect is similar to the thyroid gland, without a lymph node pattern; while the nodular hyperplasia or Hashimoto thyroiditis are the frequent findings, the main differential diagnosis is metastasis either of thyroid cancer or from other malignancy. [1][2][3][4][5] Therefore, it seems appropriate comment on some of the scarcely described cases of parasitic thyroid nodules, aiming to enhance the awareness and suspicion index among primary health care workers about investigations on the real nature of these changes. [2][3][4][5] Dos Santos VM, et al reported a 53-year-old female with Hashimoto thyroiditis and hypothyroidism, who had a right pre-laryngeal parasitic node (1.6 x 0.7 x 0.5cm); and a 99mTc isonitrile scintigraphy showed topic thyroid without uptake by the nodule.…”

“…[1][2][3][4][5] Therefore, it seems appropriate comment on some of the scarcely described cases of parasitic thyroid nodules, aiming to enhance the awareness and suspicion index among primary health care workers about investigations on the real nature of these changes. [2][3][4][5] Dos Santos VM, et al reported a 53-year-old female with Hashimoto thyroiditis and hypothyroidism, who had a right pre-laryngeal parasitic node (1.6 x 0.7 x 0.5cm); and a 99mTc isonitrile scintigraphy showed topic thyroid without uptake by the nodule. 2 The biopsy revealed epithelial cells with nuclear atypia, oncocytic changes, germinative centers, and lymphoid infiltration, mimicking metastasis of papillary thyroid carcinoma, diagnosis which was discarded by the absence of marginal sinuses in the silver staining.…”