Mesothelial tumors
Benign multicystic mesothelioma

Author: Vaidehi Avadhani, M.D. (see Authors page)

Revised: 22 March 2018, last major update August 2013

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

PubMed Search: Benign multicystic mesothelioma pleural

Cite this page: Avadhani, V. Benign multicystic mesothelioma. website. Accessed August 16th, 2018.
Definition / general
  • Now termed multicystic mesothelial tumor of borderline biologic potential (MMTBBP)
  • Very rare in pleura - most cases reported have been from peritoneum
  • Usually reported in women of reproductive age (mean age 37 years)
  • Peritoneum, pleura, pericardium
Clinical features
  • Pleura: localized mass found on imaging studies
  • Abdomen: chronic or intermittent abdominal pain (most common), abdominal distension, urinary hesitancy
Radiology description
Radiology images

Images hosted on other servers:

Peritoneal tumors:

Sagittal endovaginal sonogram

IV contrast enhanced CT scans

Case reports
  • Surgical resection
  • Also sclerosants, hormonal therapy, radiotherapy, chemotherapy
  • Peritoneal lesions may recur
  • Usually patients with recurrent disease have long survival as lesion grows slowly
Gross description
  • Well circumscribed mass of multiple thin walled cysts with serous fluid, easily dissected from surrounding tissue
Gross images

Images hosted on other servers:

Peritoneal masses:

Multicystic mass

Multiple thin walled, irregular shaped cysts

Microscopic (histologic) description
  • Cystic spaces lined by single layer of bland cuboidal mesothelial cells, some with hobnailing
  • Cysts are filled with eosinophilic serous fluid
  • Stroma is hypocellular and collagenized
  • No nucleoli or mitotic activity
Microscopic (histologic) images

Images hosted on other servers:

Peritoneal tumors:

Multiple thin walled, irregular cysts

Loose fibrous stroma between cysts

Mesothelial cells line cysts

Cytology description
  • Fluid cytology and cell blocks show benign appearing mesothelial cells in flat sheets and small clusters, with low N/C ratio, rounded nuclei and indistinct nucleoli (Diagn Cytopathol 2010;38:192)
Positive stains
Negative stains
Electron microscopy description
Differential diagnosis