Solid cell nests of the thyroid

Abstract

The ultimobranchial thyroid solid cell nests (SCN), irregular structures of about 1 mm in maximal diameter, are usually found in the middle third of the thyroid lateral lobes. SCN are basically composed of non-keratinizing epidermoid cells which lack intercellular bridges and are immunohistochemically positive for a panel of high and low molecular weight keratin proteins, as well as for carcinoembryonic antigen. In addition, SCN display isolated or grouped peripheral calcitonin-immunoreactive 'clear' (C) cells in up to 54 per cent of cases. The SCN central lumen, when present, is usually surrounded by mucinous cells; in addition, it may contain desquamated cells, cell debris, acid mucosubstances, characteristic PAS-positive granular material after diastase treatment, and colloid-like material. The so-called mixed follicles, structures lined by epidermoid cells of SCN and follicular epithelium, are often found as an additional component of the ultimobranchial remnants. The relationship of SCN to thyroid parenchymal cells and the probable implications of the thyroid 'ultimobranchial system' to tumour histogenesis are analysed. Pitfalls that may emerge with regard to SCN in practical pathological approaches are emphasized.

Solid Cell Nests in Hashimoto’s Thyroiditis Sharing Features with Papillary Thyroid Microcarcinoma

“…SCN can also be misinterpreted as squamous metaplasia of follicular thyroid cells, primary or metastatic squamous cell carcinoma, thyroglossal cyst, C-cell hyperplasia, and medullary microcarcinoma [2,9]. The distinction between these latter lesions and SCN can usually be made on the basis of the hematoxylin and eosin (H&E) appearance, but can be confirmed by immunohistochemistry as SCN were reported as usually negative for thyroglobulin and TTF-1 and strongly reactivity for p63 [20].…”

“…Previous studies have described the histological and immunohistochemical features of SCN [2,3,6,[9][10][11][12][13][14][15]. Four different types of SCN have been reported [2,7]: (1) SCN type 1 are mainly composed of small round or oval groups of elongated or even spindle shaped cells with centrally located, oval to fusiform nuclei with uneven nuclear envelope showing occasional grooves, and scanty eosinophilic cytoplasm which are called "main cells" (floret-like features), surrounded by collection of lymphocytes; (2) SCN type 2 have large polygonal cells with abundant cytoplasm and distinct cell boundaries (epidermoid-like features); (3) SCN type 3 are characterized by cystic structure lined by flattened or large polygonal cells; and (4) SCN type 4 are composed of structures lined by main cells and follicular epithelium (so-called mixed follicles; Table 1).…”

“…Other cells with round nuclei and clear cytoplasm may be present. SCN are found in 3% of routinely examined thyroid glands and in one study were identified in 61% of thyroids serially sectioned [2].…”

“…C-cells have accounted for a minor proportion of the solid cell nest population and were characterized by clear cytoplasm and centrally located, small compact nuclei [2,9,19].…”

Coexistence of papillary and medullary carcinoma of the thyroid gland-mixed or collision tumour? Clinicopathological analysis of three cases

“…A further supportive fact is the common presence of both C cells and thyroglobulin producing, follicle forming cells within solid cell nests (Harach 1985(Harach , 1987. Solid cell nests, first described by Getzowa (1907), have been regarded as remnants of the ultimobranchial body (Harach 1985(Harach , 1987(Harach , 1988Ozaki 1991), because of the presence of C cells. A common origin of thyrocytes and C cells is also suggested by the fact that and were able to isolate a thyroglobulin-like 27 S glycoprotein from human medullary thyroid carcinoma as well as canine C cells.…”