Branchial cleft-like cysts in Hashimoto's thyroiditis: A case report and literature review

Ultimobranchial body cyst in an adult horse: clinical, histopathologic, and immunohistochemical features

A 9-y-old Mangalarga Marchador gelding was referred to a veterinary hospital because of a swelling on the upper right side of the neck. Ultrasound examination revealed a multilocular structure adjacent to the thyroid gland with low echogenic content suggestive of fluid. The mass was removed surgically. Histologically, the cystic cavities in the surgical sample were filled with abundant eosinophilic secreta and lined by cuboidal, segmentally ciliated, columnar epithelium with interspersed goblet cells. Segmental crowding of the multilayered lining of the cyst was noted. Immunohistochemistry suggested the presence of both C cells and follicular cells, given the positivity of the immunomarkers calcitonin and TTF-1, respectively. The histogenesis of ultimobranchial cysts is uncertain. Based on clinical, histopathologic, and immunohistochemical identification, the cystic structure in this case is compatible with an ultimobranchial body cyst.

Thyroid Lymphoepithelial Cysts Mimicking Calcified or Solid Nodules on Ultrasonography

Purpose

Thyroid lymphoepithelial cysts (TLECs) are rare, and detailed ultrasonography (US) findings have not been reported. This study aimed to examine in detail the US findings for 32 TLECs and to clarify the diagnostic problems associated with them.

Materials and Methods

We examined 32 TLECs resected from 21 patients at the Kuma hospital between January 2008 and April 2018. All patients underwent US before resection. From the patients’ medical records, we retrospectively assessed US reports and photographs of TLECs.

Results

The following four types of TLECs were classified: cystic, mixed solid and cystic, pseudo-solid, and pseudo-calcified types. The incidences were 50.0%, 12.5%, 12.5%, and 25.0%, respectively. Among the four types, pseudo-calcified TLECs were the smallest in size (mean: 7.1 mm). Of 24 nodules that had been interpreted in US reports, 11, 9, 1, 2, and 1 were benign, very low, low, intermediate, and high, respectively. Calcification and intramural solid growth were not identified by histological examination.

Conclusion

We should be aware that approximately half of TLECs do not exhibit US appearances typical of simple cysts, and TLECs may mimic calcified or solid nodules on US, although the reason remains unknown.

Derivation of thyroid lymphoepithelial cysts from follicular cells

The pathogenesis of thyroid lymphoepithelial cysts is controversial, and two hypotheses have been proposed, namely derivation from branchial-derived remnants or from squamous metaplasia of the follicular cells. The aim of this study was to clarify the pathogenesis of thyroid lymphoepithelial cysts. We performed pathological and immunohistochemical examination of 21 thyroid lymphoepithelial cysts, 13 non-neoplastic squamous metaplasia samples without thyroid carcinoma, 13 solid cell nests, and 14 lateral cervical cysts. On ultrasound, half of thyroid lymphoepithelial cysts were interpreted as calcified nodules regardless of no calcification. Thyroid lymphoepithelial cysts and squamous metaplasia tended to be located in the central and lower portions of the thyroid, while solid cell nests were located in the upper and central portions (p < 0.05). In 95.2% of patients with thyroid lymphoepithelial cysts and all patients with squamous metaplasia, lesions were histologically associated with chronic thyroiditis forming lymph follicles. Hashimoto's disease was serologically confirmed in 18 patients with lymphoepithelial cysts (85.7%) and 10 patients with squamous metaplasia (76.9%). Immunohistochemically, lymphoepithelial cysts showed nuclear positivity for PAX8, thyroid transcription factor 1, and p63. One lateral cervical cyst (7.1%) showed positive staining for PAX8, while solid cell nests were PAX8-negative. In three (14.3%) cases of thyroid lymphoepithelial cysts, squamous cells located on the superficial layer were focally and weakly positive for CEA. We concluded that thyroid lymphoepithelial cysts originate from follicular cells and are unrelated to solid cell nests and lateral cervical cysts arising from branchial-derived remnants.

Thyroid FNA biopsies comprised of abundant, mature squamous cells can be reported as benign: A cytologic study of 18 patients with clinical correlation

BACKGROUND

A thyroid nodule comprised almost exclusively of mature, benign-appearing squamous cells is an uncommon finding in fine-needle aspiration (FNA) biopsies of thyroid nodules. Reporting such specimens was not originally addressed by The Bethesda System for Reporting Thyroid Cytopathology. The authors correlated the biologic behavior of the specimens with their benign cytologic appearance through clinical, radiographic, and surgical follow-up.

METHODS

The pathology archives of 3 tertiary hospitals were searched for thyroid FNA specimens consisting of mature squamous cells without atypia. The authors reviewed all available slides and included only cases that were moderately to highly cellular; nucleated or anucleate squamous cells without atypia comprised the vast majority of the cellularity. Available clinical information and/or thyroid ultrasound examination(s) were reviewed by an endocrinologist or radiologist, respectively.

RESULTS

A total of 18 patients (7 men and 11 women; age range, 19-76 years) with 20 nodules met the prespecified inclusion criteria. The average nodule size was 2.1 cm. Common sonographic characteristics included a well-defined appearance, the lack of internal vascularity, a thin outer wall, general hypoechogenicity with low-intermediate internal echoes, and posterior acoustic enhancement. Clinical and radiographic follow-up (mean, 3.8 years; range, <1 to 9 years) was available for 9 patients, and all nodules were stable. All 4 cases with histologic follow-up were benign squamous-lined cysts.

CONCLUSIONS

The findings of the current study suggest that thyroid FNA specimens comprised almost exclusively of mature squamous cells can be reported as benign. Cancer Cytopathol 2018;126:336-41. © 2018 American Cancer Society.