Foam cells are derived primarily from monocytes/ macrophages, 2,3 but the majority of research into the nature of foam cells has focused on relatively advanced lesions and has generally used a single monocyte/macrophage marker, such as CD68, MOMA-2, Mac-2, or Mac-3. 4 -6 Some of these markers (eg, CD68) can be expressed by both macrophages and dendritic cells (DCs) and thus cannot differentiate between these cell types. There are, however, several markers expressed preferentially by DCs, including CD11c, major histocompatibility complex (MHC) class II and 33D1 antigen. 7 An in vitro study showed that macrophages, when treated with oxidatively modified lipids, differentiate into foam cells and in the process acquire expression of DC markers. 8 The identity of foam cells is of great significance, because DCs possess distinct functions from macrophages and DC-derived foam cells may retain some or all of their properties.DCs are found in the intima of human arteries. 9 We and others have shown that DCs reside in the normal murine aortic intima in areas predisposed to atherosclerotic lesion formation and are absent in areas protected from atherosclerosis. 10,11 We refer to these cells as resident intimal DCs. Macrophages are rare in the normal aortic intima but are abundant throughout the adventitia. 10 DCs are also found in atherosclerotic lesions, in both humans 12 and animal models. 13,14 The role of DCs in atherosclerosis is not well understood. DCs isolated from the normal aorta are capable of cross-presenting antigen 15 ; however, it is not likely that antigen presentation occurs in the normal intima, because T lymphocytes are very scarce in this location. 10 DCs may migrate to secondary lymphoid organs, where they encounter a wide repertoire of T cells. This phenomenon may decrease during atherogenesis, because hypercholesterolemia impairs migration of DCs to lymph nodes. 16 DCs can also regulate inflammation by producing either proinflammatory or tolerogenic factors in different contexts. 17,18 Recent studies suggested that lesion Original received May 29, 2009; resubmission received October 7, 2009; accepted October 28, 2009. From the Toronto General Research Institute (K.E.P., S.-N.Z., M.C., S.N., J.J.-B., M.I.C.), University Health Network; and Departments of Immunology (K.E.P., J.J.-B.) and Laboratory Medicine and Pathobiology (J.J.-B., M.I.C.), University of Toronto, Canada.Correspondence 19 We hypothesize that resident intimal DCs may play a key role in the initiation of atherosclerosis by engulfing lipid and differentiating into foam cells.Conditional depletion of specific cell types can be accomplished using transgenic murine models in which the simian diphtheria toxin receptor (DTR) is placed under the transcriptional control of a cell-specific promoter. A single injection of diphtheria toxin (DT) into mice bearing a murine CD11c promoter-DTR transgene (CD11c-DTR mice) induces apoptosis and depletes DCs, which express high levels of CD11c. 24 The murine homolog of DTR binds DT with very low affinit...

Skin lightening (SL) for cosmetic reasons is associated with profound negative impacts on well-being and adverse effects on the skin, resulting in immense challenges for dermatologists. Despite current regulations, lightening agents continue to dominate the cosmetic industry. In this review, our international team of dermatologists tackles the topic of SL as a global public health issue, one of great concern for both women’s health and racial implications. We have examined SL in Africa, Asia, the Middle East, and the Americas. We aim to inspire a global discourse on how modern dermatologists can utilize scientific evidence and cultural competency to serve and protect patients of diverse skin types and backgrounds. In doing so, we hope to promote healthy skin and inclusive concepts of beauty in our patients and society.

Lichen planus pigmentosus inversus (LPPI) is a rare variant of lichen planus characterized by slate grey to dark black-brown macules, papules, or patches occurring in the skin folds. We present a case of LPPI in an 11-year-old girl, the second-youngest case and only the third pediatric case. This article also reviews the differential diagnosis and treatment of LPPI.

Patients with possible CD spend considerable time in the health care system before they undergo definitive assessment. Understanding the reasons for not seeking care may be useful for promoting earlier evaluation and intervention to result in better outcomes.