Pathology of Mesothelioma:
cases of Mesothelioma equates with diffuse malignant mesothelioma.
- In the initial stage the disease is characterized by numerous small nodules or plaques covering visceral and parietal serosal surfaces.
- At the later stage individual nodules fuse and form a diffuse, sheetlike thickening often encasing and compressing the lungs or the intestines and sometimes the liver and spleen.
- The final stage of the disease are marked by massive encasement of the viscera with matting of the affected structures, commonly causing complete obliteration of the pleural or peritoneal cavity.
This may cause fatal functional disturbance.
In some cases tumour extends through the chest or abdominal wall along a needle biopsy tract or a scar from a previous excision.
This complication should be kept in mind when planning thoracoscopy or needle biopsy or when aspirating fluid for cytological examination or relief of symptoms.
Macroscopically the tumour varies greatly in appearance and may be firm and rubbery or soft and gelatinous.
Cut surface is greyish-white and glistening in appearance.
There may be foci of hemorrhage or necrosis.
Gross appearance according to the site of the lesion: (Pathology of malignant mesothelioma. Histopathology. 1997;30(5):403-18).
Pleura: Parietal pleura is usually more extensively involved ;
Usually located in the inferior aspect of the cavity and diaphragm ;
Lung parenchyma may be involved in some cases ;
Distance metastases has been reported in about 50% cases.
Peritonium: Variable growth pattern ; Indistinguishable from extensive carcinomatosis ;
Multiple coalescing grey-white nodule in greater omentum and visceral peritoneum ;
Tumour is firm or hard in consistency ; Cystic and mucoid areas may be present ;
Encasement of the intra-abdominal organs ;
Intramucosal tumour may present as multiple intestinal polyps ;
Liver and spleen may contain tumour nodules ;
Other mesothelial lesions may be present: - Well differentiated papillary mesothelioma ; multicystic mesothelioma; deciduoid mesothelioma ; adenomatoid tumour.
Pericardium: Not a common site for diffuse mesothelioma ; Tumour may encase heart and great vessels.
Tunica Vaginalis Testis: Rare tumour presents as multiple nodules ;
Invade testicular parenchyma, spermatic cord and subcutaneous tissue of penis ; Hydrocele is usually present ;
Differential diagnosis: Adenocarcinoma of rete testis , metastatic tumour from primary lung, renal and prostatic carcinomas.
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