Lymph nodes & spleen, nonlymphoma

Ectopic tissue / inclusions

Mesothelial inclusions

Last author update: 1 June 2014
Last staff update: 10 April 2023

Copyright: 2003-2023,, Inc.

PubMed Search: Mesothelial cell inclusions [title]

Jayalakshmi Balakrishna, M.D.
Page views in 2022: 5,715
Page views in 2023 to date: 2,543
Cite this page: Balakrishna J. Mesothelial inclusions. website. Accessed June 5th, 2023.
Definition / general
  • Benign mesothelial inclusions
  • Benign metastasizing mesothelial cells
  • Very rare occurrence
  • Mediastinal and abdominal lymph nodes
  • Rare - cervical lymph nodes
  • Transportation of these cells through the lymphatics to the lymph node during injury or manipulation at the primary site of the origin
  • They undergo a degeneration, and thus it becomes difficult to find them
Clinical features
  • Incidental finding
  • Enlarged lymph nodes
  • Site specific symptoms
  • Biopsy plus immunohistochemistry
Radiology images

Contributed by Kristin Dittmar, M.D.

Enlarged lymph node due to mesothelial inclusion

Prognostic factors
  • Benign process with no significant clinical implications
Case reports
  • Depends upon the clinical presentation / underlying cause
  • In incidental findings, none necessary
Gross description
  • Enlarged lymph nodes with yellowish tan to gray white, smooth to mottled surface
Microscopic (histologic) description
  • Small clusters and singly scattered, round to polygonal cells, seen in the subcapsular and interfollicular sinuses of the nodes
  • These cells show a round, vesicular nucleus with small nucleolus
  • The nuclear - cytoplasmic ratio is low
  • No mitotic activity is detected
  • There is no extranodal or parenchymal infiltration of the cells
  • Tiny spaces are seen in between the cells of the clusters (mesothelial windows)
Microscopic (histologic) images

Contributed by Debra L. Zynger, M.D.

Core biopsy

High power


CK5 / 6


Positive stains
Differential diagnosis
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