This case was a 47-year-old male with a diagnosis of right pleural mesothelioma with metastasis to the lymph nodes. His social history includes 20-25 years living in Mexico after which time he resided in the United States. His reported work history indicated a possible exposure to asbestos-containing floor tiles for 2 years, between 1988 and 1990, when he worked in janitorial and maintenance services for a supermarket.
A right radical extrapleural pneumonectomy was performed to remove the malignant tumor. On gross examination, the right lung pleura had a nodular appearance with 60% encasement of the lung by the mesothelioma and invasion into adjacent skeletal muscle. There was adherence of the parietal pleura to the visceral surface.
Microscopic examination revealed an epithelial tumor of the visceral and parietal pleura (). The tumor displays large sheets of pleomorphic cells with vesicular nuclei, prominent nucleoli and moderately abundant eosinophilic cytoplasm in a tubulopapillary pattern (). The malignant cells invade the adipose tissue, skeletal muscle and the diaphragm. Areas of parietal pleura were also found to contain parietal pleural plaques with acellular, hyalinized collagen in a “basket-weave” pattern (). Immunochemical stains of the tumor sections were positive for pan-cytokeratin and calretinin (, cytoplasmic and nuclear staining) and negative for CD15 and CEA. Ferruginous bodies were abundant throughout lung tissue that was not involved by tumor (). These ferruginous bodies were also present in areas with interstitial fibrosis ().
Figure 1 H&E staining shows an epithelial tumor of the visceral pleura (A, 10 x magnification) with a tubulopapillary growth pattern of the tumor cells (B, 40 x magnification) as well as acellular hyalinized collagen of a parietal pleural plaque (C, 20x (more ...)
Figure 2 H&E sections show ferruginous body formation (A, black arrow) within the lung tissue and interstitial fibrosis surrounding a ferruginous body (B, blue arrow). After lung digestion, a significant amount of ferruginous bodies was detected on the (more ...)
A lung digest was completed on 0.32 grams of the tissue from paraffin-embedded lung. The sample was digested using a sodium hypochlorite technique, as previously described [5
], and collected on a 0.45 micron pore size Millipore filter. One-half of the filter was mounted on a glass slide for ferruginous body quantification by light microscopy. This analysis revealed that there were 1,097 ferruginous bodies per gram of wet lung. The other one-half filter was mounted on a carbon disc, sputter coated with colloidal graphite and evaluated by scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA). Calculations based on the number of fibers greater than 5 microns in length indicated that there were 124,000 uncoated fibers per gram of wet tissue. EDXA was performed on thirty uncoated fibers for the identification of the fiber mineral content. 24 of these fibers contained various combinations of Al, Si, K, Na, and Ca in ratios indicative of erionite (). Six fibers contained only Al and Si in a proportion similar to the erionite fibers. There was no spectral evidence found for commercial amosite, crocidolite, or crysotile asbestos, nor non-commercial amphiboles.
Figure 3 After lung digestions, the digest filter was evaluated by scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA). The analysis revealed erionite fibers (greater than 5 microns in length) and erionite ferruginous bodies. An uncoated (more ...)
By SEM, there were 2 ferruginous bodies identified during the quantitative analysis which indicated a burden of 2,480 ferruginous bodies per gram of wet tissue. These ferruginous bodies were analyzed by EDXA, as were an additional eight ferruginous bodies identified in a non-quantitative scan of the filter. Of the ten ferruginous bodies analyzed, eight contained various combinations of Al, Si, K, and Na in proportions indicative of erionite (). The other two ferruginous bodies contained only Al and Si, but in a proportion similar to the erionite fibers above. These studies indicate that there were 124,000 uncoated erionite fibers per gram of wet lung tissue and 2,480 erionite ferruginous bodies per gram of wet lung tissue.