Hypersensitivity syndromes

The hypersensitivity syndromes are a group of diseases in which the cutaneous vasculature is altered through immunologic or nonimmunologic mechanisms. These reactions range in severity from mild to life-threatening and can be triggered by drugs, infectious agents, foods, or environmental allergens. Although their causes may vary, the morphologic appearance of these entities may be similar making a clinical diagnosis a challenge.     

Neurocutaneous syndromes

Neurocutaneous syndromes are congenital or hereditary conditions that have many features in common: hereditary transmission, involvement of organs of ectodermal origin (nervous system, eyeball, retina, and skin), slow evolution of lesions in childhood and adolescence, and disposition to fatal malignant transformation. Except for Sturge- Weber syndrome, these major neurocutaneous syndromes are genetically determined, although sporadic cases can occur. This article reviews the clinical features of the more common neurocutaneous syndromes, including tuberous sclerosis complex, neurofibromatosis, Sturge-Weber syndrome, Ehlers-Danlos syndrome, and von Hippel-Lindau disease.     

Paraneoplastic syndromes

As the lengthy but nonetheless incomplete review suggests, paraneoplastic syndromes are protean in their manifestations and, for the most part, poorly understood. Indeed, some of the more common abnormalities in cancer patients that might be considered paraneoplastic--such as anorexia-cachexia syndrome or unexplained fever--have not been discussed because they are so poorly understood. Most of the syndromes reviewed are either clearly paraneoplastic or strongly associated with cancer. Their clinical importance does not lie in the number of patients affected; it is a small minority. Instead, the syndromes may occasionally be helpful in the diagnosis of cancer or in monitoring response to cancer therapy. They may also be confused with the effects of metastatic disease. In some patients, amelioration of the syndromes can reverse the patient's dominant symptoms and thus provide significant clinical palliation. In a more general context, studies of etiologic mechanisms in paraneoplastic syndromes may offer insights into a variety of unexplained abnormalities in cancer patients. The best-understood syndromes result from tumor production of biologically active substances or, to a lesser extent, from autoimmune phenomena. These would appear to be probable mechanisms in many recognized paraneoplastic syndromes of uncertain etiology and perhaps in some heretofore unrecognized paraneoplastic syndromes. Finally, paraneoplastic syndromes could also hold clues to the neoplastic process. Better understanding of the ways in which tumors regulate remote effects--such as release of TGFs--may ultimately enhance our knowledge of tumor growth itself.     

Deconstructing culture-bound syndromes

Ethnopsychiatry comprises a large field of literature written from diverse perspectives, disciplines and orientations. Its status as an interdiscipLinary activity presents formidable obstacles to researchers interested in comparative problems and the development of generalizations. These difficulties can be demonstrated by even a cursory examination of the material written on what has come to be called 'culture-bound syndromes'. In spite of the considerable body of specific studies written about these 'ethnic psychoses', as Devereux termed them, debates continue to swirl over how to define them, whether they are manifestations of psychopathology, and, by implication, the degree to which the categories of Western psychiatric nosology are readily transferable to other cultural and historical settings. This paper does not attempt to play the role of broker between universalists and particularists. If anything I favor the particularist position with respect to the impossibility of directly applying diagnostic categories across cultural boundaries. On the other hand I would not deny that there are universal processes which take their form through complex interaction with particular cultural, historical and social settings. The goal of showing how general forms can only be realized in particular settings is a vital one for anthropology, and the literature on culture-bound syndromes illustrates the problems involved. The problems can be severe, but no more so than those facing any observer of an exotic cultural setting. Because I perceive parallels between problems of translation in social and anthropology in general and the issues that have emerged in discussions of culture-bound syndromes, I seek to return to basic issues in this essay to examine some aspects of culture-bound syndromes that should be examined before assertions about pathology are made.     

Paraneoplastic hormonal syndromes

We can define paraneoplastic syndromes as a combination of effects occurring far from the original location of the tumour and independently from the local repercussion of its metastases. Paraneoplastic hormonal syndromes depend on the secretion of hormonal peptides or their precursors, cytokines and, more rarely, thyroidal hormones and Vitamin D, which act in an endocrine, paracrine or autocrine way. Sometimes, paraneoplastic syndromes can be more serious than the consequences of the primary tumour itself and can precede, develop in parallel, or follow the manifestations of this tumour. It is important to recognise a paraneoplastic hormonal syndrome for several reasons, amongst which we would draw attention to three: 1) It can lead to the diagnosis of a previously undetected, underlying malign or benign neoplasia; 2) It can dominate the clinical picture and thus lead to errors with respect to the origin and type of primary tumour; and 3) It can follow the clinical course of the underlying tumour and thus be useful for monitoring its evolution. The molecular mechanisms responsible for the development of these syndromes are not well-known, but it is believed that they might be inherent to the mutations responsible for the primary tumour or depend on epigenetic factors such as methylation. In this review, we consider the following paraneoplastic hormonal syndromes: malign hypercalcaemia, hyponatraemia (inappropiate secretion of the antidiuretic hormone), ectopic Cushing's syndrome, ectopic acromegaly, hypoglycaemia due to tumours different from those of the islet cells and paraneoplastic gynaecomastia; we make a brief final reference to other hormones (calcitonin, somatostatin, and VIP).