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hyaluronic acid (alcian blue positivity digested have had all the morphological characteristics by hyaluronidase). of a WDPM.3 In this case mitoses were Immunohistochemical examination of the described as and no recurrence "infrequent", J Clin Pathol: first published as 10.1136/jcp.45.11.1030 on 1 November 1992. Downloaded from tumour showed cytokeratin (CAM 5 2) and was noted after follow up for a year.3 No epithelial membrane antigen (EMA) positivity. mitoses were present in the case ofBarbera and Carcinoembryonic antigen (CEA) and Leu Rubin,2 and the patient was well after one M-1 antibody were not expressed. year. Well differentiated papillary mesothelioma is usually a small lesion in both the peritoneum and tunica vaginalis.' 2 Most occur in the Discussion peritoneum, and very rarely in the tunica The tunica vaginalis is lined by mesothelium: a vaginalis, with only two definite cases having full spectrum of mesothelial proliferations been reported so far.2 3 Other sites include the from completely benign to overtly malignant epicardium6 and pleura.7 Peritoneal lesions are can occur. more common in females, but cases have been Reactive hyperplasia of the tunica vaginalis described in the peritoneum in males.5 may be attended by papillary change4 but this Clinically, this lesion seems to run a bland is usually a focal finding and not the dominant course, but a course more akin to low grade histological configuration. malignancy in the peritoneum has not been More importantly, this lesion needs to be entirely ruled out.' With this uncertainty distinguished from malignant mesothelioma regarding their behaviour, these lesions are and papillary carcinoma, which display nuclear designated "well differentiated" rather than pleomorphism, mitotic activity, and areas of "benign".' stromal invasion. In papillary areas multi- Probably not associated with exposure to layering of the epithelium is allied to the asbestos, the precise aetiology is not clear. cytological atypia. Well differentiated malig- Surgical excision with regular follow up is the nant mesothelioma may have foci of well current management. developed tubulopapillary structures devoid of cellular atypia. However, such areas are invari- 1 Daya D, McCaughey WTE. Well differentiated papillary mesothelioma of the peritoneum. A clinicopathologic ably accompanied by others showing obvious study of 22 cases. Cancer 1990;65:292-6. malignant features. The key microscopic fea- 2 Barbera V, Rubino M. Papillary mesothelioma of the tunica vaginalis. Cancer 1957;10:183-9. ture of WDPM is the lack of cellular and 3 Johnson DE, Fuerst DE, Gallager HS. Mesothelioma of the architectural atypia. tunica vaginalis. South MedJ 1973;66: 1295-7. In their 22 4 Foyle A, Al-Jabi M, McCaughey WTE. Papillary peritoneal analysis of such tumours occur- tumors in women. Am J Surg Pathol 1981;5:241-9. ring in the peritoneum Daya and McCaughey 5 Goepel JR. Benign papillary mesothelioma ofperitoneum: A histological, histochemical and ultrastructural study of six found mitoses in only one case (the number cases. Histopathology 1981;5:21-30. not being quantified).' Six cases also occurring 6 Larsen TE. Serosal papiloma of the epicardium. Arch Pathol 1974;97:271-2. in the peritoneum described by Goepel' did 7 Yesner R, Hurwitz A. Localised pleural mesothelioma of not show mitotic activity. The case reported by epithelial type. J Thorac Surg 1953;26:325-9. 8 Daya D, McCaugheyWTE. Pathology of the peritoneum: A Johnson, Fuerst, and Gallager in the tunica review of selected topics. Semin Diagn Pathol http://jcp.bmj.com/ vaginalis of a 23 year old man, would seem to 1991 ;8:227-89.

J Clin Pathol 1992;45:1030-1031 on September 27, 2021 by guest. Protected copyright. Mucous metaplasia of the pleura

M S Bashir, P N Cowen

Abstract no abdominal signs were detected clinically or Academic Unit of A case of mucous metaplasia of mesothe- on ultrasound scan. She had never complained Pathology, lium in an 80 year old woman is described. of respiratory symptoms, and a chest x-ray Department of Clinical Medicine, Its cause is unknown, but it is important picture after pleurocentesis, when pleural University of Leeds, not to confuse it with secondary tumour. biopsy was performed, was normal. There was Leeds General nothing to suggest new growth in this patient Infirmary, Great Clin George Street, Leeds (y Pathol 1992;45:1030-103 1) and she died about a week later. Necropsy was LS1 3EX not performed and cause of death was given as M S Bashir cardiorespiratory failure. P N Cowen Case report Correspondence to: M S Bashir An 80 year old woman presented with upper Accepted for publication abdominal pain and weight loss. A right sided Pleural histology 18 May 1992 pleural effusion was found on examination but This showed inflamed vascular connective Mucous metaplasia of the pleura 1031

Photomicrograph ofpart of the metaplastic mesothelium showing goblet cells (haematoxylin and J Clin Pathol: first published as 10.1136/jcp.45.11.1030 on 1 November 1992. Downloaded from eosin).

CD . f*

tissue lined by a strip ofmesothelial cells which cellular oedema because staining for mucin had become detached in parts. Some of these was negative.3 were apparently normal mesothelial cells but In the case described there was a clear were continuous with columnar cells contain- transition from mesothelium to columnar cells ing basal nuclei with apical vacuoles which in an elderly patient who had no evidence of were periodic acid Schiff positive. A repre- fibrocystic disease of the pancreas. The cells sentative example of this is shown in the figure. rested on a basement membrane and the All of the mucin containing cells were well vacuoles were periodic acid Schiff positive, differentiated and showed no evidence of a thus indicating mucous metaplastic transfor- possible malignant origin. They did not stain mation of the pleura. The exact cause of this for carcinoembryonic antigen by immunoper- change is not known but its recognition is oxidase. important to avoid it being misinterpreted as malignant tissue. This would be quite likely if the metaplastic change occurred in an area of http://jcp.bmj.com/ proliferating reactive mesothelium. The mor- Discussion phology and negative staining for carcinoem- The histology of the pleura indicated mucous bryonic antigen are helpful in confirming the metaplasia, described by Dunnill' as occurring benign nature of this appearance. in older patients with fibrocystic disease of the pancreas. He described the condition at nec-

1 Dunnill MS.Neonatal and paediatric pulmonary disease. In: on September 27, 2021 by guest. Protected copyright. ropsy in a 17 year old female.2 A possible Dunnill MS, ed. Pulmonary pathology. 2nd ed. Edinburgh: pathogenesis in this case was ectopia of bron- Churchill Livingstone, 1987:439-59. 2 Dunnill MS. Metaplastic changes in the visceral pleura in a chial epithelium following rupture of a bron- case of fibrocystic disease of the pancreas. J Pathol chiectatic abscess. Bacteriol 1959;77:299-302. 3 Spencer H. Diseases of the bronchial tree. In: Spencer H, Spencer describes a case of vacuolation of ed. Pathology of the Lung. Vol 1. Oxford: Pergamon Press mesothelial cells ascribed to intra- and inter- 1985:131-65.