The Diagnosis of Desmopiastic Malignant Mesothelioma and Its Distinction From Fibrous Pleurisy: A Histologic and Immunohistochemical Analysis of 31 Cases Including p53 Immunostaining

Abstract

A b s t r a c tWe studied 31 patients with fibrotic pleural lesions and classified them as desmopiastic malignant mesothelioma (DMM)

Sarcomatoid mesothelioma: a clinical–pathologic correlation of 326 cases

“…These tumors are characterized by a deceptively 'bland' appearance, raising a differential diagnosis of benign fibrous pleuritis or pleural plaque. 8,26 It is worth noting at this point that the role of immunohistochemistry is more limited for sarcomatoid malignant mesotheliomas than for epithelial mesotheliomas, because staining for mesothelial markers is less often positive than in epithelial malignant mesotheliomas. 6 For example, in this series of sarcomatoid malignant mesotheliomass, only 31% showed positive labeling for calretininwidely regarded as the most specific and reliable marker for mesothelial differentiation in epithelioid malignant mesotheliomas-and the staining was usually focal with predominantly cytoplasmic and occasional nuclear reactivity.…”

“…6,33 The combination of positive CK expression and calretinin seems to be highly characteristic of sarcomatoid malignant mesothelioma, but CK and calretinin immunohistochemistry cannot always discriminate between malignant mesothelioma versus synovial sarcomas and spindle-cell carcinomas. 8,20,27,32,[34][35][36] In cases in which CK staining is negative, the gross distribution of tumor and absence of any history of an antecedent primary soft tissue sarcoma or intrapulmonary mass lesion with radiological features of a primary lung carcinoma may aid in making the diagnosis. [37][38][39] In this context, we advise extreme caution in making a diagnosis of sarcomatoid malignant mesothelioma in a patient with a mass present within the lung parenchyma, especially for apical masses, which frequently involve the pleura secondarily.…”

“…[2][3][4][5] Histological diagnosis of sarcomatoid malignant mesothelioma-notably the desmoplastic and lymphohistiocytoid subtypes-can be more problematic than for epithelioid or biphasic malignant mesotheliomas, because of similarity with benign fibrous pleuritis in the case of desmoplastic malignant mesothelioma, and with non-mesothelial tumors such as malignant fibrous histiocytoma and even non-Hodgkin's lymphoma, and because of restricted or inconsistent expression of mesothelial markers on immunohistochemistry. [6][7][8] We consider the correct diagnosis to be imperative because of the different prognostic implications of other disorders that mimic sarcomatoid malignant mesothelioma (eg, desmoplastic malignant mesothelioma vs fibrous pleuritis), including the choice of treatment regimes (eg, sarcomatoid malignant mesothelioma vs pleural synovial sarcoma), and because of the medicolegal implications.…”

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

“…10 Stromal invasion is often more difficult to recognize in spindle cell proliferations of the pleura than in epithelioid proliferations. The invasive malignant cells are often deceptively bland, resembling fibroblasts, and pancytokeratin staining is invaluable in highlighting the presence of cytokeratin-positive malignant cells in regions where they should not normally be present: in the connective tissue, adipose tissue, or skeletal muscle deep to the parietal pleura, or invading the visceral pleura and lung tissue (or other extrapleural structures present in the sample) ( Figure 5, A and B).…”

“…Fortunately, most cases that show bland necrosis also show invasive growth. 10 Similarly, the presence of ''frankly sarcomatoid foci'' is a distinctly subjective determination and one would be reluctant to base a diagnosis of malignancy on its presence alone, since reactive processes may show marked cytologic atypia, albeit typically at the surface of the process.…”