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Sarcoidosis is a systemic granulomatous disease characterized by the presence of non-caseating granulomas. Its etiology remains obscure. A plausible hypothesis suggests that a complex interplay of host factors, infectious processes, and non-infectious environmental factors, matched with a susceptible genetic background, results in a pathway that leads to systemic granulomatous inflammation. Although presentations of sarcoidosis vary enormously, multi-organ involvement is a common feature. Cutaneous involvement occurs in about 25% of patients with protean manifestations and variable prognoses. Skin manifestations are divided into specific lesions with histopathologically evident non-caseating granulomas and nonspecific lesions arising from a reactive process that does not form granulomas. A peculiar form of cutaneous sarcoidosis is represented by sarcoidal lesions at sites of trauma that has caused scarring. The pathogenesis of scar sarcoidosis remains unknown. Scar sarcoidosis is also associated with herpes zoster infection, surgery, and tattooing. Such heterogeneous events, along with those at the sites of chronic lymphedema, thermal burns, radiation dermatitis, and vaccinations, occur on areas of vulnerable skin labeled "immunocompromised districts". Numerous options are available for the treatment of cutaneous sarcoidosis. Although corticosteroids remain the treatment of choice for initial systemic therapy, other nonsteroidal agents have proven effective and therefore useful for long-term management. Tumor necrosis factor-α antagonists such as infliximab may have a role in the treatment of cutaneous sarcoidosis, especially in refractory cases that are resistant to standard regimens. Elucidation of the relationship of sarcoidal granulomas with malignancy and immunity may facilitate a better understanding of some pathomechanisms operating in neoplastic and immunity-related disorders., (© 2014 The International Society of Dermatology.)

Background: In earlier papers, we suggested that the aggravation of psoriasis by antimalarial drugs (analogous to hypolipidemic drugs) could be initiated by a break in the epidermal barrier. We suggested that these drugs exerted their effect by inhibiting epidermal transglutaminase activity, and supported this hypothesis by demonstrating the effect of hydroxychloroquine sulfate (HCQS) on the morphology of cultured skin and on liver transglutaminase activity. In the present article, we describe, for the first time, the morphologic changes induced by HCQS on cultured skin of psoriatic patients., Methods: Uninvolved (apparently normal) skin explanted from the back of two psoriatic patients was cultured in the presence of 9.2 and 13.8 mM of HCQS for 3 days. The morphologic changes were evaluated in a blind manner. The experiment was repeated twice., Results: Significant changes in the epidermal morphology of psoriatic skin cultured in the presence of HCQS, compared with skin cultured without the presence of the drug, were observed. The most striking changes were enhanced and irregular keratinization and dermo-epidermal detachment and cleft formation. No parakeratosis or other characteristics of psoriasis were observed., Conclusions: The first changes caused by HCQS on the cultured skin of psoriatic patients are not characteristic of psoriasis, and include hyperproliferation and enhanced and irregular keratinization. The present experimental study gives further support to the hypothesis that HCQS causes an initial break in the barrier function of the epidermis (probably by inhibiting transglutaminase activity), which is followed by a physiologic response of the epidermis aimed at barrier restoration. This rather nonspecific stimulus to epidermal proliferation is probably sufficient to trigger psoriasis, in vivo, among genetically predisposed patients.

Background: Several lipid-lowering agents, when given topically, show a profound effect on skin morphology. Because of low bioavailability of these drugs for keratinocytes, the incidence is extremely low clinically. The most appropriate way to study the effect of hypolipidemic drugs on keratinocytes is by artificial exposure of the skin to high drug concentrations., Objective: To study the effects of gemfibrozil on the morphology of in vitro cultured normal human skin explants. As gemfibrozil induces barrier disruption by inhibiting epidermal sterologenesis, essential for a competent permeability barrier, it is interesting to investigate the morphologic changes associated with this phenomenon. Studying the epidermal changes induced by lipid-lowering agents is important, not only because it might lead to a better understanding of the effects of these drugs on keratinocytes, but as it might also unlock the door to a wider knowledge of the pathomechanism of disorders of cornification., Methods: Normal human skin from patients undergoing mastectomy was cultured in the presence of 2, 5, and 10 mM of gemfibrozil for 4 days The morphologic changes were evaluated by three blinded observers. Their reports were matched and collated., Results: The cultured skin in the presence of gemfibrozil showed cell crowding of keratinocytes in the lower part of the epidermis, indicating epidermal hyperplasia and increased proliferation. Intercellular edema with the formation of small cavities in the epidermis, intracellular edema, and vacuolar alteration of keratinocytes in the upper portion of the epidermis were also observed. The intensity of these changes tended to parallel the gemfibrozil concentration. Some dermo-epidermal detachments did not correlate with the gemfibrozil concentration, but rather with tissue characteristics peculiar to each explant., Conclusions: The morphologic changes caused by gemfibrozil to normal human skin were not characteristic of psoriasis, and included intracellular and intercellular edema in the upper portion of the epidermis and cell crowding, indicating epidermal hyperplasia in the lower portion of the epidermis. The present experimental study gives further support to the hypothesis that hypolipidemic drugs cause an initial break in the barrier function of the epidermis, followed by a physiologic epidermal response, aimed at barrier restoration. This rather nonspecific stimulus to epidermal proliferation may trigger psoriasis in predisposed patients.

Background: Antimalarials are some of the most notorious drugs which may induce psoriasis, with 25% of all reported cases being associated with them. Antimalarials do not induce psoriasis de novo, but trigger subclinical psoriasis. In a previous report, we suggested that antimalarials exert their effect by interfering with the epidermal transglutaminase (TGase) activity., Objective: To verify this hypothesis by examining the effect of hydroxychloroquine sulfate (HCQS) on cultured human skin and on TGase activity in vitro., Materials and Methods: Skin samples from normal donors were cultured in the presence of HCQS for 4 days, and then processed for microscopic examination. TGase activity was assayed in the presence of HCQS and compared with blanks., Results: Significant changes in epidermal morphology were seen in all explants cultured in the presence of HCQS at all concentrations employed. Areas of enhanced and irregular keratinization were observed in the upper epidermis, while a loss of cell polarity, with keratinocyte crowding and disarray, was seen in the lower epidermis. In addition, we observed intraepidermal splitting at different levels and dermo-epidermal detachments. HCQS showed a concentration-dependent inhibition of TGase activity., Conclusions: We suggest that HCQS causes an initial break in the barrier function of the epidermis by inhibiting TGase activity; this is followed by a physiologic response of the epidermis aimed at barrier restoration. This rather nonspecific stimulus to epidermal proliferation is probably sufficient to trigger psoriasis in predisposed individuals or aggravate it in psoriatic patients.

Kaposi's sarcoma appeared on a chronically lymphedematous leg of a 75-year-old man. Immunologic investigations revealed a lack of cellular immune response confined to the involved lower limb. Regional disorders of immune surveillance are thought to play an important role in the early stages of Kaposi's sarcoma.