Papillary Thyroid Carcinoma in a Branchial Cleft Cyst without a Thyroid Primary: Navigating a Diagnostic Dilemma

Abstract

We report a rare case of papillary thyroid carcinoma incidentally found within a branchial cleft cyst. Only four other cases have been described in the literature. A total thyroidectomy and selective neck dissection was performed, and no evidence of occult primary disease was found after review of fine sections. Branchial cleft cysts are the most common lateral neck masses. Ectopic thyroid tissue within a branchial cleft cyst is an unusual phenomenon, and papillary thyroid carcinoma arising from this tissue is extremely rare. Clinicians are left with a diagnostic dilemma when presented with thyroid tissue neoplasm within a neck cyst in the absence of a thyroid primary—is this a case of metastatic disease with a missed primary or rather carcinoma arising in ectopic thyroid tissue? A thorough discussion of the etiologies of these lateral neck masses is reviewed including the embryogenesis of thyroid tissue in a branchial cleft cyst. The prognosis of patients with papillary thyroid carcinoma in lateral neck cysts without a primary site identified appears to be good following excision of the cyst and total thyroidectomy. Other management recommendations regarding these unique lateral neck malignancies are also presented.

Intrathyroidal Lymphoepithelial (Branchial) Cyst: Diagnostic and Management Challenge of a Rare Entity

“…This could suggest a causal relationship between the two entities, but it seems more likely that these were coincidental findings. 4,[22][23][24][25] Coincidental or not, in our reported case, a 0.3 cm area of papillary microcarcinoma was also found.…”

“…The remaining six cases showed different degrees of chronic inflammation. [4][5][6][7][8][9][10][12][13][14][15][16][22][23][24][25][26][27][28][29][30][31]…”

Thyroid Papillary Carcinoma in a Branchial Cleft Cyst—A Case Report

“…Lack of extra thyroidal invasion, negative lymph nodes with no evidence of metastasis and anatomical separation of the cyst and the thyroid are findings to support such a hypothesis. From our knowledge, this clinical entity is rare and is confirmed only in very few reports in the literature [14].…”

Wolf in sheep’s clothing-ectopic papillary thyroid carcinoma

“…This theory of cystic degeneration and development of de novo carcinoma are probably the answers to how a malignant tissue can transform from a benign lesion, as the case discussed here. [9] Microscopically, the combination of expressions of Napsin A and TTF-1 markers in immunohistochemistry staining helps to differentiate a primary lung adenocarcinoma from a metastatic lung malignancy. If both markers are positively expressed, a diagnosis of primary lung adenocarcinoma is confirmed and is highly specific.…”