Abstract
Florid mesothelial hyperplasia typically occurs in the pelvis, abdomen, or chest associated with an underlying neoplastic or inflammatory process. These lesions are of clinical significance because they can mimic a neoplasm. Early reports were published in the 1970s, but only a few case series of such lesions have been published in the gynecologic pathology literature. Here, we report a case of florid mesothelial hyperplasia with an infiltrative growth pattern, mimicking an invasive carcinoma. The lesion was associated with endometriosis forming a mass lesion in the abdominal wall. Histologically, tubular arrangements and nests of mesothelial cells, some with artifactual slit-like spaces, formed a stellate lesion adjacent to endometrial glands and stroma. Cytologic atypia was mild and reactive, and positive immunostaining for calretinin, WT-1, and cytokeratin 5 identified the lesion as mesothelial and benign. We describe in detail the histologic findings in this case and review the pertinent literature. We discuss the clinically importance of this diagnostic pitfall and the path to arriving at the correct diagnosis.
Highlights
Mesothelial hyperplasia most commonly occurs in the pelvic and abdominal cavity as a reactive process, typically in response to an underlying neoplastic or inflammatory process
Reports were published in the 1970s, but only a few case series of such lesions have been published in the gynecologic pathology literature
We describe in detail the histologic findings and the immunohistochemical workup that lead to the correct diagnosis and summarize the pertinent pathology literature
Summary
Mesothelial hyperplasia most commonly occurs in the pelvic and abdominal cavity as a reactive process, typically in response to an underlying neoplastic or inflammatory process. Florid lesions of mesothelial hyperplasia are clinically significant when they become a diagnostic challenge and need to be distinguished from a neoplastic process. Our review of the gynecologic pathology literature found 55 cases of florid mesothelial hyperplasia described in three case series [3–5]. When found in staging biopsies in patients with pelvic or abdominal tumors, misinterpretation of these lesions as tumor deposits can potentially lead to erroneous upstaging with significant clinical implications [3, 5, 10, 11]. In the vast majority of cases, florid mesothelial hyperplasia arises as papillary or nodular excrescences associated with a mesothelium-lined surface. We describe in detail the histologic findings and the immunohistochemical workup that lead to the correct diagnosis and summarize the pertinent pathology literature
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