Abstract
Tumor invasion of the peritoneal membrane may have an adverse prognostic significance, but its histopathologic features can be diagnostically difficult to recognize. We observed that local peritoneal injury associated with tumor invasion is characterized by activation and proliferation of serosal stromal cells that express cytokeratin, a characteristic property of injured serosal membranes that may have diagnostic utility. To explore this, we examined 120 primary tumors of the gastrointestinal tract and pancreaticobiliary system using cytokeratin and elastic stains to assess for tumor invasion of peritoneal membranes. Peritoneal invasion by tumor was associated with retraction, splaying, and destruction of the elastic lamina and proliferation of keratin-expressing stromal cells of serosal membranes. All 82 peritoneal invasive tumors were characterized by neoplastic cells that invaded the elastic lamina and the serosal connective tissue with neoplastic cells that abutted or were surrounded by keratin-positive stromal cells, whereas all 38 tumors limited to the subserosa showed none of these features. The diagnosis of tumor invasion of peritoneal membranes is enhanced by the combined use of cytokeratin and elastic stains, which in turn would enable better histopathologic correlation with patient treatment and outcome.
Highlights
The prognosis and multidisciplinary treatment of tumors of the gastrointestinal and pancreaticobiliary system are guided by tumor staging classifications such as the American Joint Committee on Cancer (AJCC) and International Union Against Cancer (UICC) [1,2]
We examined the histopathologic changes in peritoneal membranes, and assessed the practical diagnostic utility of cytokeratin immunohistochemistry in combination with an elastic stain in the diagnosis of tumor invasion of peritoneal membranes in a variety of deeply invasive tumors of the gastrointestinal tract and pancreaticobiliary system
Tumor invasion of the peritoneal membrane was defined by neoplastic cells that invaded the elastic lamina and the connective tissue of the serosal membrane, whereas tumors confined to the subserosa lacked neither invasion of the elastic lamina nor the peritoneal connective tissue (Table 1)
Summary
The prognosis and multidisciplinary treatment of tumors of the gastrointestinal and pancreaticobiliary system are guided by tumor staging classifications such as the American Joint Committee on Cancer (AJCC) and International Union Against Cancer (UICC) [1,2]. In these classifications, the depth of mural invasion is correlated with the pathologic tumor stage (pT). Complete mural invasion with tumor penetration of the peritoneal surface is a well-recognized adverse prognostic feature that is associated with an increased risk for tumor spread and recurrence, within the peritoneal cavity, and this is reflected by a high pathologic tumor stage [3,4,5,6,7,8]. Invasion of the elastic lamina characterizes tumor invasion of the peritoneal membrane, but the elastic lamina can be difficult to detect due to its displacement, splaying, and fragmentation when invaded by tumor [9,11,12]
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