Immunohistochemical profile of paratesticular serous papillary adenocarcinoma and tunica vaginalis facilitates distinction from malignant mesothelioma

Our plain-English summary of Immunohistochemical profile of paratesticular serous papillary adenocarcinoma and tunica vaginalis facilitates distinction from malignant mesothelioma, by P.R. Anchala, R. Dhir, A.V. Parwani, et al (International Journal of Surgical Pathology, 2011).

The study

• Authors: P.R. Anchala, R. Dhir, A.V. Parwani, D.L. Zynger
• Journal: International Journal of Surgical Pathology
• Published: 2011;19(5):692-8
• Type of article: Case report
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Testicular and paratesticular tumors resembling mullerian epithelium of the ovary are extremely uncommon. This study reports a case of paratesticular serous papillary adenocarcinoma (SPA) in an 87-year-old man that was misdiagnosed as malignant mesothelioma (MM) and is 37 years older than previous cases, highlighting that SPA does not occur exclusively in young patients as described. Immunohistochemistry revealed expression of pankeratin, CAM 5.2, CK7, CK903, Ber-EP4, vimentin, S100, and CEA and virtually no expression of CK5/6, CK20, calretinin, thrombomodulin, or glypican 3. Expression of adjacent nonneoplastic tunica vaginalis mesothelium was assessed in this patient and additional specimens. Profiles of paratesticular SPA and MM were summarized and compared with paratesticular mesothelium. Nontumoral stromal and entrapped mesothelial expression were 2 diagnostic pitfalls in this case that have not been previously described. Based on these data, a panel of markers and the use of sections containing nonneoplastic mesothelium to facilitate interpretation is recommended.

In plain English

This article was a case report combined with a review of earlier published cases. It described an 87-year-old man with right scrotal swelling whose right testis was surgically removed. An outside institution first diagnosed his tumor, which arose from the tunica vaginalis (the lining around the testis), as malignant mesothelioma, epithelial type. The case was sent to the authors because calretinin staining was weaker than expected. They diagnosed paratesticular serous papillary adenocarcinoma (SPA), a rare tumor resembling ovarian tumors. The tumor cells stained for Ber-EP4, S100 and focally CEA, and essentially not for calretinin or CK5/6. Normal surrounding mesothelium showed the opposite pattern. Focal calretinin staining in fibrous tissue and in trapped normal mesothelium contributed to the misdiagnosis. No tumor was found 1 month after surgery. Counting this case, 10 SPA patients had been reported, aged 16 to 87. The article did not report whether this patient had asbestos exposure. The authors recommended a panel of stains, with normal mesothelium as an internal control, and noted that outcome data are limited.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Case report of one patient, with a review of previously published cases of paratesticular serous papillary adenocarcinoma
• Who was studied: One 87-year-old man with right scrotal swelling who underwent right radical orchiectomy. Three additional samples of nonneoplastic testicular tissue were also stained. The literature review covered 10 reported patients with paratesticular SPA, including this one.
• Exposure: Not an exposure study, and the article does not report this patient's asbestos history. Citing earlier literature, the authors noted that none of 6 previously reported SPA patients who were asked reported asbestos exposure.
• Main results:
  • Under the microscope the tumor showed frequent mitoses (27 per 10 high-power fields), many of them abnormal.
  • The outside institution diagnosed malignant mesothelioma, epithelial type with tubulopapillary features.
  • The case was referred to the authors' institution because calretinin staining was weaker than anticipated.
  • The authors diagnosed paratesticular serous papillary adenocarcinoma based on histology and the staining profile.
  • In the tumor cells, Ber-EP4 stained approximately 70% of cells.
  • In the tumor cells, S100 stained strongly in 30% of cells.
  • In the tumor cells, CEA stained focally (5%).
  • Calretinin was not expressed in the tumor cells, though background staining was noted.
  • CK5/6 stained very rare tumor cells (less than 1%).
  • Nonneoplastic paratesticular mesothelium showed a profile similar to malignant mesothelioma: diffuse calretinin, thrombomodulin and CK5/6, and no Ber-EP4, CEA or S100.
  • Three additional cases of nonneoplastic testicular tissue showed staining similar to the index case.
  • Background staining and focal strong calretinin staining in the fibrous stroma could be misread as mesothelioma staining and contributed to the misdiagnosis in this case.
  • Normal mesothelium trapped between tumor cells stained strongly for calretinin.
  • The authors stated that nonneoplastic mesothelium can serve as an internal control when SPA and malignant mesothelioma are being considered.
  • One month after surgery the patient had no evidence of tumor.
  • Literature review: including this case, 10 patients with SPA of the tunica vaginalis had been reported.
  • Literature review: reported SPA patients ranged in age from 16 to 87 years, with a mean of 38 years.
• The authors' conclusion: The authors recommended using a panel of antibody stains to tell paratesticular SPA apart from malignant mesothelioma. They also advised careful scrutiny of areas of focal strong staining that may be residual mesothelium.
• Limitations the authors state:
  • Because so few cases exist, the authors stated it is unknown whether the malignant histologic features affect prognosis.
  • The authors stated that outcome data for paratesticular SPA are quite limited.
  • The authors stated that more data are needed on which clinical and pathologic characteristics affect prognosis.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Paratesticular, Adenocarcinoma, Tunica Vaginalis, Malignant Mesothelioma, Epithelium, Immunohistochemistry, Ber-EP4, Calretinin.

Related studies

• Papillary serous carcinoma of the tunica vaginalis testis — P. Becerra, M.A. Isaac, et al. (2000)
• Value of mesothelial and epithelial antibodies in distinguishing diffuse peritoneal mesothelioma in females from serous papillary carcinoma of the ovary and peritoneum — R.L. Attanoos, R. Webb, et al. (2002)
• Case Report of a Well-Differentiated Papillary Mesothelioma of the Tunica Vaginalis in an Undescended Testis With Review of Literature — P. Parcesepe, S. Sina, et al. (2016)
• Loss of BAP1 expression is very rare in peritoneal and gynecologic serous adenocarcinomas and can be useful in the differential diagnosis with abdominal mesothelioma — J. Andrici, J. Jung, et al. (2016)
• Well-differentiated papillary mesothelioma of tunica vaginalis testis of unknown malignant potential: Sonographic appearance — K.W.S. Ko, K.S. Tse, et al. (2018)
• Claudin-4 as a marker for distinguishing malignant mesothelioma from lung carcinoma and serous adenocarcinoma — Y. Ohta, Y. Sasaki, et al. (2013)

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