Lymph nodes - not lymphoma
Inclusions, pigment, ectopic cells or tissue
Mesothelial cell inclusions

Author: Jaya Balakrishna, M.D. (see Authors page)
Editor: Abdelsalam Sharabi, M.D.

Revised: 28 June 2018, last major update June 2014

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Mesothelial cell inclusions [title]

Cite this page: Balakrishna, J. Mesothelial cell inclusions. website. Accessed October 19th, 2018.
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

Images hosted on PathOut server:

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

Images hosted on PathOut server:

Contributed by Debra Zynger, M.D.

Core biopsy

High power


CK5 / 6


Positive stains
Electron microscopy images

Images hosted on other servers:
Missing Image

Long, slender microvilli

Differential diagnosis