Document ganV69zkwG0dRno3j8x2rRoDN

1 1 The pathology of mesotheliomata 271 Tumours of this fibromatous type were described by Klemperer and Rabin (1931) as forming a localized mass in the serosal space, but all my cases showed diffuse involvement of the pleura or peritoneum. One case showed a large mass in addition to diffuse involvement of the pleura. Both epithelial and fibromatous elements were found in 41% (14 cases), and both types might be found in the same microscopical field (Fig. 12) in the same anatomical area or in different sites of tumour (Figs. 8 and 9). All lesions in bone (direct invasion of vertebrae or ribs) were fibromatous in type (Fig. 8), often with epithelial type in all other lesions. Metastases in lymph nodes were usually of epithelial type irrespective of the type of the primary tumour (Fig. 9). It is possible that the structure of the organ may affect the histological appearances of the tumour. In contrast to mesothelioma, when a carcino matous metastasis is present in bone, it is fre quently `scirrhous', that is it shows a fibrous our. iclei tain and dis:ion tese vith ;act ter), but are but lour / to nccs cells :ady tria- ^ent. ossi;een. few fig. 6. Case 10. Pleural tumour. The central cells are spindle-shaped but still show vesicular nuclei and eosino philic nucleoli. Haematoxylin and eosin, X 750. t The cells of the `fibrous' types are spindle- shaped with oval nuclei arranged with longitudinal axes parallel to those of the cells. The oval nuclei are often vesicular, and prominent eosinophilic \ nucleoli are common (Fig. 6). The cells are also in parallel, loosely arranged in indistinct fascicles i that gently fuse into each other, unlike the angled intersections of the leiomyosarcoma or fibro sarcoma. On transverse sections the fascicles are > often clearly rounded and slightly whorled. Occa 4 sionally the cells are arranged parallel to the surface of the underlying viscus with little or no fasciculation. Reliculin fibres surround these cells in a closely h .* woven meshwork of thin strands, and occasionally 1 the fibres are thick, dense, and brown. The latter are found in acellular, hyaline areas, which are common in these tumours. Mitoses are uncom r* mon, but a few tumours show areas of pleo- fig. 7. Case 5. Fibromatous pleural tumour. Collagenous morphism with tumour giant cells and frequent tissue at top ofphotograph. Inflammatory cells at bottom. j y-- mitoses. Figure 7 shows the histology of a fibro- The similarity of this area to benign pleural thickening matous tumour with abundant collagen formation. (Fig. 11) is striking. Haematoxylin and eosin, X 110.