In 12 autopsy cases of myotonic dystrophy, the most frequently observed histopathologic lesions of the cardiac conduction system were fibrosis, fatty infiltration and atrophy. Fibrosis involved the sinus node in 6 cases, atrioventricular (AV) node in 7, AV bundle in 8, bundle branches in 10 and ventricular myocardium in 11. Fatty infiltration was observed in the sinus node in two cases, AV node in two, AV bundle in six, bundle branches in one and ventricular myocardium in nine. Atrophy was prominent in the AV bundle in five and bundle branches in eight. Lymphocytes infiltrated the conduction system in three cases and were associated with myotonic dystrophy in two and varicella myocarditis in one. Ventricular myocytes were hypertrophied in seven cases, vacuolated in three and exhibited disarray in two. The distribution and extent of conduction system lesions tended to correspond to antemortem electrocardiographic abnormalities, including prolonged PR interval in six cases, intraventricular conduction delay in six and bundle branch block in four. Cardiac involvement by myotonic dystrophy may have contributed to sudden death in four cases.

The diagnostic identification of sweat gland carcinomas is hampered by their rarity and their histologic resemblance to various visceral tumors, leading to confusion with metastatic lesions. In this series, 14 cases of eccrine carcinoma in five male and nine female patients, ranging in age from 13 to 84 years, are described. Ten tumors strongly resembled infiltrating ductal adenocarcinomas of the breast, and were thus classified as ductal. Three had a prominent mucinous matrix, similarly explaining their categorization as mucinous carcinomas. Finally, one neoplasm was a classic eccrine porocarcinoma. Four patients with ductal eccrine carcinomas suffered metastasis, and a 50% mortality rate was observed among this group of ten cases. In contrast, only one of three mucinous carcinomas metastasized, although all of these lesions recurred locally, as did the single porocarcinoma. None of the latter four neoplasms proved fatal. The results of conventional special stains in these 14 cases are discussed, and histologic features that they shared, and which may be utilized in distinguishing eccrine carcinomas from benign sweat gland tumors, are presented.

Extraocular sebaceous carcinomas are uncommonly seen neoplasms, and have been confused in the past with basal cell carcinomas showing sebaceous differentiation. In contrast to the latter tumors, however, sebaceous carcinomas have a distinct risk of aggressive behavior. This study presents clinicopathologic data on five cases of sebaceous carcinoma arising in cutaneous locations outside of the ocular adnexae. Four of five patients were men, and the average age at diagnosis was 63 years. Three tumors occurred on the face, one arose in the skin of the neck, and another occurred on the penis, an anatomic site that is extremely rare for sebaceous carcinoma. Three tumors metastasized, and two patients died of tumor or with residual tumor growth. In light of this behavior, the premise that extraocular sebaceous carcinomas rarely spread to distant sites may need reexamination.

Recent reports have implicated a possible but undefined role for reactive oxygen species in the induction and mediation of apoptosis. In the present study, the role of free radicals and metal ions in apoptosis induced in rat thymocytes by dexamethasone and etoposide was examined. Copper chelators, but not iron specific chelators, inhibited apoptosis induced by both these stimuli. Several antioxidants also possessed potent inhibitory effects. We therefore propose that diverse agents may induce apoptosis in thymocytes by a common mechanism involving a copper mediated Fenton reaction, generating site specific hydroxyl radicals, possibly as a result of activation of the redox sensitive transcription factor NF-KB.