Types

 unifocal
 multifocal

Localization

Localization

 diaphragmatic mesothelial cysts
 peritoneal surface (surface of the peritoneum)

• peritoneal cul-de-sac
• intestines
• urinary bladder
• uterine adnexa
• round ligament within the pelvis
• inguinal canal
• free-floating cysts in the peritoneal cavity

 visceral

• intra-hepatic mesothelial cysts (#12489001#)
• splenic mesothelial cysts

Synopsis

 Gross appearance: polycystic lesions
 Size: microscopic size to 2 cm in diameter
 thin-walled, semitranslucent, filled with clear or yellowish fluid or gelatinous contents
 cysts were with a single layer of flattened or cuboid mesothelial cells (CK+, calretinin+)
 diffuse squamous cell metaplasia
 cells focally forming small papillae
 vacuolated cells
 no mucus

Immunohistochemistry

 CK +
 calretin +

Associations

 diaphragmatic defect (diaphragmatic hernia)

References

 Arber DA, Strickler JG, Weiss LM. Splenic mesothelial cysts mimicking lymphagiomas. Am J Surg Pathol. 1997 Mar;21(3):334-8. PMID: #9060604#