Malignant mesothelioma: A histomorphological and immunohistochemical study of 24 cases from a tertiary care hospital in Southern India.

Indian Journal of Cancer 2018 April-June [Link]

Hui M, Uppin SG, Bhaskar K, Kumar NN, Paramjyothi GK


Malignant mesotheliomas are histologically heterogeneous neoplasms. Definite diagnosis requires a varied panel of immunohistochemical (IHC) markers to differentiate these from histological mimics. Only a few case series have been reported in the Indian literature where mesotheliomas have been analyzed on routine histology and IHC.
To evaluate the histological features of malignant mesothelioma and to elucidate the best possible immunomarker combination useful in different scenarios.
A total of 24 cases of malignant mesotheliomas of different sites encountered over a 6-year period were retrospectively analyzed with regard to their histomorphology and IHC findings.
The pleura was the most common site of involvement (16 cases) followed by peritoneum (5 cases) and pericardium (3 cases). Epithelioid mesothelioma was the most common histological type (15 cases, 62.5%) followed by sarcomatoid (5 cases, 20.84%), deciduoid (2 cases, 8.34%), and 1 case each of desmoplastic and biphasic mesothelioma. Among the mesothelial markers, WT1 was positive in 17 of 20 (85%) cases and calretinin was positive in 20 of 21 (95.23%) cases. D2-40 and CK5/6 were positive in all cases where they were studied. Adenocarcinoma markers TTF-1, napsin A, and CEA had very high negative predictive value in ruling out mesothelioma.
The differential diagnosis of mesotheliomas varies with histological type and tumor location. Judicious use of various combinations of IHC markers in different situation has been highlighted in this article.