Chiara Grassani1, Letizia Gnetti2, Massimo Melissari2, Francesco Paolo Pilato2, Francesco Evaristi2, Michele Potenzoni1, Luigi Benecchi3
  • 1 Ospedale di Vaio (Fidenza)
  • 2 Istituto di Anatomia Patologica Ospedale di Parma (Parma)
  • 3 Istituti Ospitalieri di Cremona (Cremona)


Malignant mesothelioma ( MM) of the tunica vaginalis is a very rare neoplasm occurring in this area, and it is usually not diagnosed until surgery [1-2]. Less than 100 cases of of malignant mesothelioma have been reported in the last 40 years in literature. The prognosis of malignant mesothelioma is unfavorable. We present an unusual case of malignant mesothelioma of the testis, incidentally found, occurred in a 55 years old male.The patient with a long term history of hydrocele, recurring orchiepididimytis poorly responsive to antibiotic therapy, underwent testicular exploration for acute testicular pain. No previous exposure to asbestos was described.

Methods and results

The preoperative scrotal ultrasound showed a corpuscolate hydrocele with a maximum thickness of 27 mm, a few of internal septums and a normal testicular parenchyma. No other preoperative radiologic investigations were done.
A right orchiectomy with emiscrotal access was performed.
The surgical specimen, fixed in formalin for 24 hours, was macroscopically described, sampled and included in paraffin. The 3-5 micron histologic sections were stained with Hematoxylin-Eosin and Shiff Periodic Acid for conventional stains. Successive immunohistochemical studies included: Calretinin, WT-1, HBME-1, Vimentin, P53, D2-40, Ck-pool, Desmin, PLAP, CEA, BEREP-4, S100, B72.3 and Ki-67.
Macroscopically a normal looking testis appears surrounded by the tunica vaginalis containing citron-glassy hydrocele fluid.
Microscopically, the didimal parenchyma was only characterized by a low reduction of germinal line and edema, but the tunica vaginalis was constituted of epithelioid with mild to moderate degree of atypia, arranged in tubular pattern and in rosetta-like cluster with infiltrative growth and stromal invasion. The neoplastic process, displayed a positive stain for Calretinin, WT-1, HBME-1, Vimentin, P53, D2-40, Ck-pool, whereas it was negative for Desmin, PLAP, CEA, BEREP-4, S100, B72.3. The Ki-67 proliferative index was about 50%.


Mesothelial lesions represent a broad group of disorder arising from serosal membrane, associated to asbestos exposure, long term hydrocele, herniorraphy [5-7].
Pleural mesothelioma account about the 68-80% of the total cases, peritoneal the 9,1 to 24,1%, whereas the neoplasms affecting the testis represent only the 0,3 to 1% of all mesothelioma.
Usually the surgical specimens and the preoperative radiologic investigation reveal the presence of a macroscopical evident lesion i.e nodular masses, focal thickening or papillary fronds of the tunica vaginalis [2-3]. The light microscopic findings indicate usually a high grade pleomorphic cellularity with epitheliod, spindle or biphasic morphology, organized in papillae, tubules with solid and cribriform areas of the tunica vaginalis, ifiltrative growth with stromal invasion and areas of necrosis [1-11].
The case we report differs from usual presentation of mesothelioma of the tunica vaginali testis. Clinically the patient displayed an acute testicular pain and less asbestos exposure.The surgical speciments revealed no macroscopical lesions. The histology showed only a bland cellularity in tubular pattern.
The above clinical-histological factors and the lack in literature, of conclusive immunoistochemical staining to safely discriminate malignant mesothelioma form reactive mesothelial reaction [6], put our case in differential diagnosis with mesothelial iperplasia, adenomatoid tumor and well differentiated papillary mesothelioma [8-9-10-11].
Since the extensive sampling, the wide infiltrative growth, and the high KI 67 index the final diagnosis of malignant mesothelioma was made.
Malignant mesothelioma of tunica vaginalis has a lethal prognosis: the mean survival time is 26-36 months [4].
The patient completed a regular follow up with abdomen and chest CT every 6 months and at the 18 months follow up visit the patient has no sign of local recurrence and metastases.


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