Peritoneal Malignant Psammomatous Mesothelioma

Psammoma bodies (PBs) are observed most commonly in papillary thyroid carcinoma, meningioma, and papillary serous cystadenocarcinoma of the ovary. We report one case of peritoneal malignant mesothelioma (PMM) with massive deposition of PBs. A 72-years-old man presented with abdominal swelling and marked weight loss. Contrast enhanced computed tomography showed fluid diffuse in peritoneal recesses, thick septa with micronodules in the greater omentum and adjacent enhancement of the thickened peritoneum. The explorative laparoscopy showed diffuse minute parietal peritoneal nodules. The peritoneal biopsy revealed a superficial papillary growth of malignant epithelial-like cells with diffuse involvement of submesothelial tissues. Massive deposition of PBs was observed. Nuclear and cytoplasmic calretinin immunoreactivity was present in neoplastic cells along with membranous D2-40 and membranous/cytoplasmic cytokeratin 5 staining. The patient was treated with chemotherapy (gemcitabine, vinorelbine, cisplatin). PBs may represent an active biologic process ultimately leading to degeneration/death of tumor cells and retardation of growth of the neoplasm. It may also serve as a barrier against the spread of tumor. Psammomatous malignant mesothelioma may simulate serous psammocarcinoma of the peritoneum. The behavior of serous psammocarcinoma is more closely similar to borderline serous tumor than to serous carcinoma. Further studies are necessary to establish if massive deposition of PBs may define a new variant of psammomatous malignant mesothelioma with a favorable impact to the prognosis of usual psammomatous malignant mesothelioma, as well as in serous psammocarcinoma of the peritoneum.