Histopathology 2015 August 14 [Epub ahead of print] [Link]

Krasinskas AM, Borczuk AC, Hartman DJ, Chabot JA, Taub RN, Mogal A, Pingpank J, Bartlett D, Dacic S.



The prognostic significance of histological subtyping of epithelioid pleural mesotheliomas has been recently reported, but similar data are lacking in peritoneal mesotheliomas. We investigated possible relationships between histological growth patterns of epithelioid peritoneal mesotheliomas, clinicopathologic features and patient outcome.

Methods and Results

84 cases of chemotherapy-naive epithelioid peritoneal mesothelioma were classified into tubulopapillary, micropapillary, papillary, tubular, solid and trabecular growth patterns. Pathologic features such as depth of invasion, lymphocytic host response, mitotic count, nuclear grade, lymphovascular invasion, lymph node metastasis, and stromal desmoplasia were analyzed. The most common histological patterns were solid (n = 37, 44%), tubulopapillary (n = 24, 29%) and micropapillary (n = 11, 13%). The overall median survival was 36 months. Patients with solid mesothelioma had shorter overall survival (median, 29 months) compared to patients with tubulopapillary and micropapillary growth patterns (median, 51 months and 53 months, respectively; p=.053). A high mitotic index (>5 in 50 hpf) was found to be associated with poor survival (p<.03). Moderate to severe lymphocytic host response was associated with longer median survival (p=.13) CONCLUSIONS: Our study highlights the prognostic importance of the solid growth pattern among diffuse epithelioid peritoneal mesotheliomas and reaffirms mitotic index as a predictor of overall survival.