Well-differentiated papillary mesothelial tumour

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Well-differentiated papillary mesothelial tumour
Diagnosis in short

Well-differentiated papillary mesothelial tumour. H&E stain.
Synonyms well-differentiated papillary mesothelioma (obsolete term), benign papillary mesothelioma (obsolete term)
LM papillary structures with thick fibrous cores and simple cuboidal epithelium, lacks cytologic atypia
LM DDx ovarian serous carcinoma, serous borderline tumour of the ovary, malignant mesothelioma especially papillary mesothelioma in situ
IHC calretinin +ve, CK5/6 +ve, BAP-1 retained (normal)
Site pleura, peritoneum, tunica vaginalis (testis)
Prevalence rare
Prognosis typically indolent
Clin. DDx tuberculosis, carcinomatosis, primary peritoneal serous carcinoma, others

Well-differentiated papillary mesothelial tumour, abbreviated WDPMT, is a rare benign mesothelial tumour.[1]

It was previously known as well-differentiated papillary mesothelioma, abbreviated WDPM.[1][2] It was also known as benign papillary mesothelioma. This entity should not be confused with malignant mesothelioma and benign multicystic mesothelioma.

General

  • Benign.
    • Some say it is borderline.[3]
  • Classically women of reproductive age.[4]
  • Reported in tunica vaginalis of the testis.[5]
  • Associated with asbestos exposure.[2]

Gross

Typical features for peritoneum:

  • Multiple peritoneal nodules.
  • Ascites.

DDx (peritoneum):[4]

Microscopic

Features:

  • Papillary structures with:
    • Thick fibrous cores.
    • Simple cuboidal epithelium.
      • Small nucleoli.

Note:

  • Lack cytologic atypia.

DDx:[6]

Images

  • WDPM - low mag.

  • WDPM - intermed. mag.

  • WDPM - high mag.

  • WDPM - very high mag.

  • WDPM - low mag.

  • WDPM - intermed. mag.

  • WDPM - high mag.

www:

IHC

Features:[7]

  • Calretinin +ve.
  • CK5/6 +ve.
  • BAP-1 retained (normal).[1]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 Churg A, Galateau-Salle F (October 2022). "Well differentiated papillary mesothelial tumor: a new name and new problems". Mod Pathol 35 (10): 1327–1333. doi:10.1038/s41379-022-01082-y. PMID 35440764.
  2. ↑ 2.0 2.1 Butnor, KJ.; Sporn, TA.; Hammar, SP.; Roggli, VL. (Oct 2001). "Well-differentiated papillary mesothelioma.". Am J Surg Pathol 25 (10): 1304-9. PMID 11688466.
  3. ↑ Bürrig, KF.; Pfitzer, P.; Hort, W. (1990). "Well-differentiated papillary mesothelioma of the peritoneum: a borderline mesothelioma. Report of two cases and review of literature.". Virchows Arch A Pathol Anat Histopathol 417 (5): 443-7. PMID 2122588.
  4. ↑ 4.0 4.1 Park, JY.; Kim, KW.; Kwon, HJ.; Park, MS.; Kwon, GY.; Jun, SY.; Yu, ES. (Sep 2008). "Peritoneal mesotheliomas: clinicopathologic features, CT findings, and differential diagnosis.". AJR Am J Roentgenol 191 (3): 814-25. doi:10.2214/AJR.07.3628. PMID 18716115.
  5. ↑ Chetty, R. (Nov 1992). "Well differentiated (benign) papillary mesothelioma of the tunica vaginalis.". J Clin Pathol 45 (11): 1029-30. PMID 1452778.
  6. ↑ Truong, LD.; Maccato, ML.; Awalt, H.; Cagle, PT.; Schwartz, MR.; Kaplan, AL. (Jan 1990). "Serous surface carcinoma of the peritoneum: a clinicopathologic study of 22 cases.". Hum Pathol 21 (1): 99-110. PMID 1688545.
  7. ↑ Malpica, A.; Sant'Ambrogio, S.; Deavers, MT.; Silva, EG. (Jan 2012). "Well-differentiated papillary mesothelioma of the female peritoneum: a clinicopathologic study of 26 cases.". Am J Surg Pathol 36 (1): 117-27. doi:10.1097/PAS.0b013e3182354a79. PMID 22024662.
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