Well-differentiated papillary mesothelioma of the peritoneum. A clinicopathologic study of 22 cases

Abstract

Twenty-two cases of well-differentiated papillary mesothelioma of the peritoneum (WDPMP) are described. Eighteen of the 22 patients were women. The peritoneal tumor was usually multifocal. Many of the tumors appear to be indolent or inactive and for practical purposes are benign. However, a few patients receiving adjuvant therapy have died under circumstances that make it difficult to determine whether the tumor was responsible for the death. It is suggested that adjuvant therapy be withheld from patients with WDPMP, unless there is clear evidence of progression. The cause of these rare tumors is not apparent, although three patients had had possible exposure to asbestos and two were sisters.

Mesothelioma of the tunica vaginalis: a series of eight cases with uncertain malignant potential

“…However, the authors acknowledged that the lack of long-term follow-up in their series precluded reaching definite conclusions on whether those cases with more complex architecture can be considered with certainty as welldifferentiated papillary mesotheliomas, and therefore as indolent tumors, or whether they should be considered as diffuse mesotheliomas. 3 The common histological features in all the reported cases of welldifferentiated papillary mesotheliomas are the bland nuclear cytology and low or absent (r1 mitotic figure per 10 h.p.f.) mitotic activity.…”

“…2,[8][9][10][11][12] In other reports, a tubular architecture was included as part of the histological spectrum of changes that can be seen in this entity. 1,3,6 In the original series of Daya et al, some cases with more complex architectural patterns, including focal solid growth, were also described. However, the authors acknowledged that the lack of long-term follow-up in their series precluded reaching definite conclusions on whether those cases with more complex architecture can be considered with certainty as welldifferentiated papillary mesotheliomas, and therefore as indolent tumors, or whether they should be considered as diffuse mesotheliomas.…”

“…1,3,4,6,7,8) the tumor presented as a solitary polypoid papillary mass protruding out of the surface of the tunica vaginalis, and in one case multiple separate nodules were present (no. 5) (Figures 1a and b).…”

“…While the histology of the originally described classic welldifferentiated papillary mesothelioma consisted of papillae lined by a single layer of bland cuboidal cells, more complex architectural patterns of growth, including tubulopapillary and even solid patterns, have been described and included by some investigators as part of the spectrum seen with this entity. [1][2][3] This report details our experience with eight paratesticular mesotheliomas that have histological features that are borderline between classic well-differentiated papillary mesothelioma and diffuse malignant mesothelioma. We also attempt to determine whether there are immunohistochemical differences between these borderline cases and overt diffuse malignant mesothelioma.…”

Guidelines for Pathologic Diagnosis of Malignant Mesothelioma: 2012 Update of the Consensus Statement from the International Mesothelioma Interest Group

“…Since the natural history of this subgroup is distinct from PMM, it is an important morphologic distinction from architecturally similar but more aggressive papillary epithelioid malignant mesotheliomas. 58,59 HISTOCHEMICAL STAINING IN MM The cytoplasmic vacuoles in adenocarcinomas frequently contain epithelial mucin highlighted by periodic acid-Schiff after digestion (PAS-D) and mucicarmine stains. Epithelial mucin can also be positive by Alcian blue but it is not digested by hyaluronidase.…”