Indian Journal of Pathology and Microbiology

: 2012  |  Volume : 55  |  Issue : 4  |  Page : 546--548

A unique case of well differentiated papillary mesothelioma involving an inguinal hernia

TN Anirudhan1, Ranjani Chakravarthy1, P Jothishankar2,  
1 Department of Histopathology, Apollo Specialty Hospitals, Teynampet, Chennai, India
2 Department of Surgical Oncology, Apollo Specialty Hospitals, Teynampet, Chennai, India

Correspondence Address:
T N Anirudhan
Plot No. HIG-9, IV main road, TNHB colony, Velachery, Chennai


Well Differentiated Papillary Mesothelioma (WDPM) is an uncommon tumor occurring predominantly in the peritoneum of young women with no history of asbestos exposure. In this report, we present a case of 48 year old male patient presenting with indirect inguinal hernia and incidental finding of a WDPM in the hernial sac during surgery. The unusual site of presentation and the relative rarity of this neoplasm in males evoke much clinico-pathological interest.

How to cite this article:
Anirudhan T N, Chakravarthy R, Jothishankar P. A unique case of well differentiated papillary mesothelioma involving an inguinal hernia.Indian J Pathol Microbiol 2012;55:546-548

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Anirudhan T N, Chakravarthy R, Jothishankar P. A unique case of well differentiated papillary mesothelioma involving an inguinal hernia. Indian J Pathol Microbiol [serial online] 2012 [cited 2020 Nov 24 ];55:546-548
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Well-differentiated papillary mesothelioma (WDPM) is an uncommon mesothelial tumor affecting primarily young women in the reproductive age group. The usual site of occurrence is the peritoneum, although other sites like pleura, pericardium and the tunica vaginalis may also be involved. [1] Very few cases have been reported in males with WDPM involving the hernial sac.

 Case Report

A 48-year-old male with fairly good general health status, presented with bilateral inguinal indirect hernias. There was no history of exposure to asbestos or occupation in the construction industry. A bilateral trans-abdominal laproscopic hernia repair was carried out. During the procedure, a granular lesion was incidentally found at the entrance of the left inguinal hernial sac [Figure 1]. No other similar lesion was found elsewhere in the peritoneal cavity. The lesion was excised in toto and sent for pathological examination.{Figure 1}

Grossly, an irregular grey white membranous tissue fragment measuring 1.5 cm and showing a granular surface was received. Histopathology revealed a neoplasm composed of broad papillae with edematous fibrous cores and lined by uniform cuboidal cells showing moderate eosinophilic cytoplasm and central nuclei with fine chromatin. There was no evidence of atypia, mitosis or stromal invasion [Figure 2]. Immunohistochemistry revealed a positive staining pattern for CK 5/6 (Dako, 1:100), Calretinin (Cellmark, pre-diluted) [Figure 3] and WT-1 (Cellmark, pre-diluted) [Figure 4]. The Ki-67 proliferation index was barely 1%. Negative immunoreactivity was obtained for Desmin, Carcino-embryonic antigen (CEA) and Ber-EP4. A diagnosis of WDPM was made, based on histomorphology and immunohistochemistry.{Figure 2}{Figure 3}{Figure 4}

Following this, the patient was further investigated with a 320 slice CT scan of the abdomen and chest, which revealed no other lesions in the body. The patient was advised regular follow up; chemotherapy was not instituted. His first post surgical follow-up was uneventful.


Well-differentiated papillary mesothelioma is an uncommon variant of mesothelial neoplasms with uncertain malignant potential. It primarily occurs in the peritoneum of young women in their reproductive age group and with no history of asbestos exposure. Other sites like pericardium, pleura and tunica vaginalis have also been described. [1],[2],[3] Most cases in men have been described in the pleura with a history of exposure to asbestos in about half the cases. [2],[3]

To the best of our knowledge, only few cases of WDPM involving inguinal hernias have been reported. [1],[4] The presenting symptoms of WDPM included ascites, acute and chronic abdominal pain, pleural effusion, menorrhagia, dyspareunia, hydrocoel; however, a majority of cases were discovered incidentally during surgery for other indications, as in this case. [1],[2],[3],[5] WDPM is considered as a neoplasm with uncertain malignant potential. The long-term survival is good as pointed out by many studies and recurrences are also rare. [1],[2],[3],[4],[5] A conclusive consensus about the role of an aggressive management utilizing chemotherapy and radiotherapy has not been reached. Studies have described adverse consequences by following an aggressive treatment strategy. [4],[5] In the present scenario, with limited clinico-pathological information, it is prudent to follow up the cases long term without embarking on radical modalities of treatment.

Differential diagnoses include mesothelial hyperplasia, malignant mesothelioma and serous tumor of low-grade malignant potential. Diffuse malignant mesothelioma with papillary pattern is a bulky tumor and the cytological atypia and cellular stratification are more pronounced, with increased mitosis. More importantly, stromal invasion is clearly present. A haphazard growth pattern, with back-to-back arrangement of the papillae, solid areas and necrosis are also evident. To distinguish between WDPM and mesothelial hyperplasia with papillary pattern may be difficult, especially in small biopsies. The papillae in mesothelial hyperplasia are less conspicuous and are either composed exclusively of mesothelial cells or are thinner with hyalinized cores and prominent vascular component. This is in contrast to the prominent, broad papillary pattern with myxoid cores of WDPM. Moreover, the lack of inflammation and the presence of reactive mesothelial changes in the adjacent serosa favor WDPM. Immunohistochemically, reactive mesothelial hyperplasia is positive for desmin and negative for EMA and p53, as compared to malignant mesothelioma, which shows a reverse pattern of immunostaining. [1],[2],[3],[6] Though useful in differentiating reactive processes from malignant mesothelioma, due to lack of experience in using these markers in the context of WDPM, extrapolation and interpretation are to be done with circumspection. [1] Serous tumor of low malignant potential is composed predominantly of columnar cells and are immunoreactive for Ber-EP4, B72.3 and MOC-31. [1] Careful assessment of the histomorphology, aided by ancillary techniques and clinico-radiological correlation, would help to resolve any diagnostic dilemma.


Well-differentiated papillary mesothelioma is a neoplasm with uncertain malignant potential affecting young women, usually in the peritoneum. WDPM are frequently diagnosed incidentally. This case has been presented for the exceedingly rare occurrence in an inguinal hernia in a male patient.


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