Thyroid & parathyroid

Other thyroid nonneoplastic

Plasma cell granuloma

Topic Completed: 1 April 2015

Minor changes: 11 August 2021

Copyright: 2015-2021,, Inc.

PubMed Search: Plasma cell granuloma thyroid

Andrey Bychkov, M.D., Ph.D.
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Cite this page: Bychkov A. Plasma cell granuloma. website. Accessed December 7th, 2021.
Definition / general
  • Marked polyclonal plasma cell infiltration with nodular or diffuse thyroid involvement
  • Also known as plasma cell granuloma type of inflammatory pseudotumor; but sclerosing type of inflammatory pseudotumor of thyroid is mainly composed of spindle cells (Eur Arch Otorhinolaryngol 2009;266:763, Endocr Pathol 2009;20:186)
  • Note: at other sites, the term inflammatory myofibroblastic tumor (or inflammatory pseudotumor) is usually used because myofibroblasts are common, and it is understood that some variants will have numerous plasma cells; however, in the thyroid gland, these cases are still called plasma cell granuloma because there are usually marked plasma cell infiltrates and myofibroblasts are usually limited
  • ~ 20 cases reported, mainly middle age and elderly women (range, 18 - 89 years, M/F = 1:4)
Clinical features
  • Neck mass with compression signs
  • Mainly indolent clinical behavior
  • Often accompanied by hypothyroidism or Hashimoto thyroiditis
  • Histology after biopsy or surgery
Radiology description
  • Nonspecific; solitary benign nodule or diffuse involvement on ultrasound, cold nodule on scintigraphy
Case reports
  • Lobectomy / partial excision for nodular lesion, total thyroidectomy for diffuse form
  • Conservative steroid and immunosuppressive therapy (J Clin Endocrinol Metab 2004;89:1534)
  • No recurrences / metastases after excision
Gross description
Gross images

Images hosted on other servers:


Cut surface

Microscopic (histologic) description
  • Abundant benign plasma cells forming sheets inside cellular fibroblastic stroma with residual thyroid tissue
  • Variable lymphocytes and histiocytes, and occasional polymorphonuclear leukocytes or eosinophils
  • Russel bodies (aggregates of immunuoglobulin) within plasma cells; Russel bodies may form grape-like clusters
  • Mott cells (plasma cells with spherical inclusions packed in their cytoplasm, Endocr Pract 2008;14:611)
  • Hürthle cell changes of follicular epithelium in thyroid with diffuse involvement
  • Rare sclerosing subtype is hypocellular with focal uniform spindle cells / myofibroblasts arranged in fascicles; large histiocytes, lymphocytes, plasma cells and scattered eosinophils are in background
Microscopic (histologic) images

Images hosted on other servers:

Plasma cells, lymphocytes and fibrous tissue

Clumps of plasma cells

Plasma cells around follicular epithelium


Kappa and lambda light chains

Positive stains
Negative stains
  • ALK1 for spindle cells (no positive cases reported so far)
Molecular / cytogenetics description
  • No monoclonality by PCR
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