Thyroid & parathyroid

Congenital / metabolic anomalies

Solid cell nests / ultimobranchial body remnants

Last author update: 1 September 2015
Last staff update: 18 November 2021

Copyright: 2003-2023,, Inc.

PubMed Search: Solid cell nests [title] thyroid

Andrey Bychkov, M.D., Ph.D.
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Cite this page: Bychkov A. Solid cell nests / ultimobranchial body remnants. website. Accessed June 3rd, 2023.
Definition / general
  • Also known as ultimobranchial body remnants, ultimobranchial body nests
  • Solid cell nests are the ultimobranchial body remnants in postnatal life
  • Rarely called compact cell nests, solid cell rests
  • Located in the middle or occasionally in the upper third of the thyroid lateral lobes and placed in a central to paracentral and slightly dorsal longitudinal axis (J Pathol 1988;155:191)
Clinical features
  • Usually an incidental microscopic finding
Case reports
  • 47 year old man with ultimobranchial body remnants (J Clin Endocrinol Metab 2012;97:2209)
  • 48 year old man with BRAF mutation in solid cell nest hyperplasia (Hum Pathol 2009;40:1029)
  • 58 year old man with carcinoma showing thymus-like elements arising in close association with solid cell nests (Thyroid 2013;23:511)
  • 65 year old man with branchial-like cysts of the thyroid associated with solid cell nests (Pathol Int 2006;56:150)
  • 70 year old man with absence of the BRAF and GRIM-19 mutations in oncocytic solid cell nests (Am J Clin Pathol 2012;137:612)
  • 70 year old man with thyroid tumor-in-tumor with basaloid differentiation and phenotype similar to solid cell nests (Int J Surg Pathol 2011;19:276)
  • "Giant" solid cell rest of thyroid (Int J Surg Pathol 2009;17:268)
  • Solid cell nest in fine needle aspiration of goiter (Diagn Cytopathol 2002;27:66)
  • Thyroid-type solid cell nests in struma ovarii (Int J Surg Pathol 2011;19:627)
  • Microscopic (histologic) description
    • Small cells in solid structures (50 - 1000 μm) interspersed between follicles
    • Usually surrounded by stroma and demarcated by adjacent thyroid follicles
    • Lobulated, nested or irregular shape on low power
    • Multiple foci (2 - 8 per section) are common (Histopathology 2016;68:866)
    • Composed of two cell populations - predominant main cells and a minority of C cells
      • Sometimes with intermingled cystic structures containing mucin and mixed follicles
    • Main cells:
      • Polygonal / elongated to round to spindle cells
      • Scant amphophilic or rarely deeply eosinophilic cytoplasm with squamoid features (but no intercellular bridges)
      • Nuclei are centrally located, oval to fusiform, with finely granular chromatin, uneven nuclear membrane, occasional nuclear grooves
    • C cells: minor population of cells with clear cytoplasm and centrally located, small compact nuclei
    • May contain ciliated columnar cells
    • May also contain cells with follicular lumen-like pattern (mixed follicles)
    • Usually have a tropism to lymphocytes because of the common embryologic derivation of SCNs and the thymus (Pathol Int 2006;56:150, Hum Pathol 2009;40:1029)
    • C cells in small clusters are common in the vicinity of solid cell nests
    • Cartilage and adipose tissue are rarely seen (Hum Pathol 1994;25:684)
    • Asioli et al classified SCN based on the solid (types 1 - 2) or cystic (types 3 - 4) patterns (Endocr Pathol 2009;20:197):
      • Type 1 (floret-like) is composed of main cells, characterized by round to oval or elongated cells with scant cytoplasm, centrally located oval to fusiform nuclei, and occasional nuclear grooves
        • The cells form round to oval groups, surrounded by lymphocytes
      • Type 2 SCN (epidermoid-like) are made of larger, polygonal cells with an epidermoid appearance
      • Type 3 has cystic architecture lined by flattened or polygonal cells
      • Type 4 SCNs (mixed follicles) have a follicular appearance and contain both follicular epithelium and small main cells
    Microscopic (histologic) images

    Contributed by Andrey Bychkov, M.D., Ph.D.

    Solid cell nests

    Histologic mimics of SCN

    Solid cell nests: p63

    Solid cell nests: thyroglobulin-

    Solid cell nests

    Nested pattern

    Cystic SCN

    Clear cells

    Occasional nuclear grooves

    AFIP images
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    Type 1 and 2 solid cell nests

    Images hosted on other servers:
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    Admixture of main and C cell

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    High mag of solid cell nests

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    Various stains

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    Galectin 3, CEA

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    Conventional solid cell nests

    Cytology description
    • Cohesive cellular group consisting of polygonal squamoid cells with lightly eosinophilic cytoplasm (no intercellular bridges), elongated to columnar shaped cells with clear cytoplasm, and scattered lymphocytes
    • Nucleus is large and centrally located, slightly irregular with evenly distributed chromatin and chromocenter (Hum Pathol 2004;35:465)
    Positive stains
    Negative stains
    Electron microscopy description
    Molecular / cytogenetics description
    Differential diagnosis
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