This report describes the 12th documented case of histiocytoid, diffuse or signet-ring cell eccrine sweat gland carcinoma of the eyelid, a rare neoplasm that characteristically affects older men and mimics distant metastasis. Clinically, the patient was thought to have a colonic metastasis. Histologically, the neoplasm comprised sheets and cords of polygonal, eosinophilic cells, with dispersed larger, rounded single cells resembling histiocytes, and cells with cytoplasmic lumina or a signet-ring appearance. Occasional duct formation was also seen. The features were reminiscent of both the histiocytoid and lobular variants of breast carcinoma. Ultrastructurally, the presence of nonintestinal type microvilli with a length : width ratio in excess of 16 were consistent with an eccrine origin, but also raised the possibility of metastatic mesothelioma. However, a metastatic lesion was excluded by clinical and imaging investigations. There has been no recurrence 3 years after primary excision.
Malignant mesotheliomas of the testis arise from the tunica vaginalis, formed from the evagination of the abdominal peritoneum into the scrotum. The immunohistochemical profile of the tunica vaginalis and associated neoplasms is often extrapolated from thoracic studies. Testicular series are uncommon, usually derived from previous case studies and literature reviews. The immunohistochemical findings in 20 cases originally diagnosed as malignant mesotheliomas are presented. Archival testicular malignant mesothelioma specimens from 1959 to 2004 were collected from hospitals throughout the United Kingdom and from the authors' own archives. Hematoxylin and eosin-stained sections were reviewed, and selected sections from each case were then examined using an immunohistochemical panel of eight antibodies: calretinin (Zymed, 1:200), epithelial membrane antigen (EMA) (DAKO, 1:50), thrombomodulin (DAKO 1:5), CK7 (DAKO, 1:100), CK5-CK6 (DAKO, 1:10), BerEp4 (DAKO, 1:25), carcinoembryonic antigen (CEA) (DAKO, 1:10), and CK20 (DAKO, 1:100). The EnVision technique was used for all antibodies. Sections were reviewed independently by three pathologists. Electron microscopy was performed on selected cases. In all cases, the morphologic light microscopy criteria for a diagnosis of malignant mesothelioma were present. However, two tumors were later excluded from the study because of diffuse strong positive immunostaining with CK20 and BerEp4 and an ultrastructural appearance of adenocarcinoma. Of the remaining cases, 15 of 18 (83%) were purely epithelioid in type, showing a mixture of papillary, tubular, and solid patterns, and 3 of 18 (17%) showed a mixed sarcomatoid/epithelioid pattern. All cases were positive for calretinin and EMA (100%), 16 of 18 (89%) were positive for thrombomodulin, and 15 of 18 (83%) were positive for CK7. CK5-CK6 positivity was present in 13 of 18 (72%) but varied in strength and distribution; 2 of 18 (11%) were positive for BerEp4. All the cases were negative for CK20 and CEA. Four of the 18 cases were examined by electron microscopy, which revealed long thin microvilli supporting a diagnosis of malignant mesothelioma. This study has shown that the immunocytochemical profile of testicular malignant mesotheliomas is similar to those arising in the pleura, with diffuse positivity for calretinin, EMA, thrombomodulin, and CK7, and negative for CK20 and CEA. Focal weak positivity may be encountered with BerEp4. However, histopathologists should be aware of the variability in CK5-6 staining in testicular specimens when compared with pleural mesotheliomas.
An experimental and a clinical study have been performed to elucidate the nature of contralateral testicular damage following unilateral testicular injury--sympathetic orchiopathia. In an experimental study significant impairment of sperm production was produced by contralateral testicular damage which did not seem to be immunologically mediated or to involve the breakdown of the "blood-testis" barrier. In 5 subfertile patients with oligozoospermia and unilateral testicular damage, removal of the damaged testicle did not result in an improvement in their semen analysis.
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