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Alopecia areata (AA) is a common form of nonscarring hair loss. It is believed to be a consequence of an immune-mediated stimulus, probably involving autoreactive T cells against antigens present in the hair follicle. The exact antigen is still unknown; however, some authors have proposed that melanogenesis-associated molecules might trigger autoimmunity. Although transient white hair regrowth is a common and well-known situation in AA, there are other types of white hair phenomena in this context, including permanent white hair regrowth, sparing of white hair in a patchy pattern, or sparing in a diffuse pattern, giving the appearance of the so-called overnight graying phenomena or canitis subita. In this review, we aim to describe the different clinical aspects of white hair in AA, as well as the proposed pathophysiologic mechanisms involved in this phenomena., (Copyright © 2023. Published by Elsevier Inc.)

Introduction: There are no reports of the density of hair follicles in the scalp of Mexican mestizo population, necessitating the determination of normal references values for this population compared with other ethnic groups., Objective: To determine the average hair follicle count on the scalp in Mexican mestizo population., Materials and Methods: A total of 50 scalp samples (25 men and 25 women) from Mexican mestizo individuals aged between 19 and 60 years, with no clinical evidence of hair disease, obtained by biopsy punch at General Hospital "Dr. Manuel Gea González" were collected over 2 years. The total follicular density, vellus and terminal hair follicles, and the percentage in anagen and catagen-telogen phase were measured. χ 2 was used as the basic statistical test., Results: The mean number of total hair follicles in our Mexican mestizo population was 23.2 ± 4.2, which is lower compared with Thais, Iranians, and Caucasians. However, the ratio of terminal and vellus hair follicles was higher than in Thais, Caucasians, and African-Americans. The percentage of terminal hairs in anagen phase was lower than in the other populations, and higher in telogen, without exceeding 15%, established as the normal reference value. There was an association between sex and terminal hairs in telogen phase ( p < 0.05). The average follicular density per mm 2 was slightly higher compared with African-Americans and Asians. Women had more terminal hairs than men., Conclusions: The density of total follicles is lower in the Mexican mestizo population compared with Iranians, Thais, and Caucasians. However, the greater number of terminal hairs compared to vellus hairs gives the appearance of greater overall volume. The results of this study can be used as a reference for diseases of the scalp in the Mexican population.

Alopecic and aseptic nodule of the scalp is a rare entity characterized by the presence of nodules or cysts with sterile punctured material and negative cultures accompanied by nonscarring alopecia in the scalp of young men. We describe a case in which an 11-year-old girl presented with a nodular, fluctuant, round lesion on the vertex with localized alopecia. High-resolution ultrasound showed a hypoechoic lesion with increased flow on Doppler imaging and culture of the citrine-yellowish material obtained by puncture was negative. The patient showed complete clinical response to treatment with topical indomethacin., (© 2017 Wiley Periodicals, Inc.)

Background: Actinic prurigo (AP) is an idiopathic photodermatosis. Although its initial manifestations can appear in 6 to 8-year-old children, cases are diagnosed later, between the second and fourth decades of life, when the injuries are exacerbated., Objective: To identify risk factors associated with clinical manifestations of AP such as skin and mucosal lesions., Methods: Thirty patients with AP and 60 controls were included in the study, the dependent variable was the presence of skin or labial mucosal lesions, the independent variables were age, sex, solar exposure, living with pets or farm animals, exposure to wood smoke, smoking habit, years smoking, and hours spent per day and per week in contact with people who smoke., Results: Of the 30 diagnosed AP patients, 66.7% were female. Patients age ranged from 7 to 71 years and the mean age was 35.77 ± 14.55 years. We found significant differences with the age and cohabitation with farm animals. Those who lived with farm animals presented 14.31 times higher probability of developing AP (95% CI 3-78.06)., Study Limitations: This is a case-control study; therefore, a causal relationship cannot be proven, and these results cannot be generalized to every population., Conclusions: The identification of factors related to the development of AP increases our knowledge of its physiopathology. Moreover, identifying antigens that possibly trigger the allergic reaction will have preventive and therapeutic applications in populations at risk of AP.

Mucormycosis is an invasive infection caused by opportunistic fungi. Rhizopus, Lichtheimia, Mucor and Rhizomucor are the most common isolated genera. Primary cutaneous mucormycosis is usually related to traumatic injuries, but immunocompromised cases are associated with underlying conditions such as diabetes mellitus and malignancies. The treatment of choice is surgical debridement and liposomal amphotericin B. We present a 40-year-old male with fever and a painful necrotic lesion on the middle back and history of poorly controlled diabetes mellitus. Rhizopus oryzae was isolated and identified using an internal transcribed spacer regions ITS1 and ITS2. An initial good response to treatment was observed; however, 7 days later a diabetic ketoacidosis due to poor adherence to treatment caused a lethal outcome.

We describe the case of a 45-year-old man who presented with a 5-month history of unilateral pruritic linear erythematous papules and atrophy on the chin and mandibular area. Dermoscopy showed areas of cicatricial alopecia with absence of follicular openings, perifollicular erythema and pigment. Lichen planopilaris of the face is a rare variant with only 13 cases reported in the literature.

Background: Actinic prurigo (AP) is an idiopathic photodermatosis, this entity requires exposure to UV-B and -A to develop lesions. Apoptosis is a physiological death program that can be initiated by a permanently active mechanism (extrinsic pathway) or irreparable damage (intrinsic pathway)., Material and Methods: Descriptive study, the sample size comprised 64 paraffin blocks of tissue with a diagnosis of AP. In H&E-stained slides, the diagnosis of AP was corroborated, and 1-µm-thick sections were processed for immunohistochemistry (IHC). A database was constructed with SPSS version 20, Inc., Chicago, IL, USA, and descriptive statistics were analyzed by X2 test and comparison of means., Results: A total of 64 cases were processed, of which 40 (62.5%) were cheilitis AP and 24 (37.5%) were AP in the skin. Of the 40 cheilitis samples, 27 were positive for Bcl-2 and caspase 3 (67.5%), p53 was expressed in 30 (75%). Of the skin lesions, p53 and caspase 3 were expressed in 18 of 24 cases (75%), and 13 were positive for Bcl-2 (54%)., Conclusions: We propose that apoptosis is the last step in the type IV subtype a-b hypersensitivity response-activation of the intrinsic pathway indicates that external factors, such as UV-A and -B are the trigger.

Background: Pemphigus vulgaris is a chronic autoimmune bullous disease, the initiation of autoimmunity has been linked to viral infections. In 1974, Krain first reported the association between herpes simplex virus and pemphigus vulgaris, since then, there have been few such studies, prompting us to examine this link., Findings: We randomly selected 15 cases of PV, the diagnosis was confirmed using hematoxylin and eosin (H&E)-stained slides-2-micron sections were deparaffinized and rehydrated to be processed by immunohistochemistry, antigen retrieval was performed with 0.1 % sodium citrate, pH 6.2, endogenous peroxidase was inactivated with 0.9 % H2O2, and washes were performed with distilled water. Finally the slides were allowed to stand for 5 min in phosphate-buffered saline (PBS). The tissues were incubated for 45 min with polyclonal anti-HSV-I, (1:150, Dako Corporation, Carpinteria, CA). The MACH 1 system was applied for 15 min to visualize the reaction using 3,3'-diaminobenzidine-H2O2 (both from Biocare Medical) as substrate under a microscope. The tissues were counterstained with Lillie-Mayer's hematoxylin (Biocare Medical). We failed to observe positivity for HSV-1 in any of the 15 PV cases that were processed., Conclusions: It is not possible to determine whether HSV-PV is a causal relationship; most studies are case reports. Thus, we propose research studies with greater methodological weight to determine the involvement of HSV in the pathogenesis of PV and demonstrate that the relationship between HSV-1 and PV is a trigger at the beginning of the disease and has an etiologic function in its pathogenesis or that it is merely a coinfection due to the immunosuppression of patients with PV.

Background: Actinic prurigo (AP) is a type of photodermatosis, the pathophysiology of which has not been determined. AP has been suggested to be a hypersensitivity reaction to the presence of eosinophils and the local production of IgE., Material and Methods: Descriptive study, using paraffin blocks of tissue that have been diagnosed with AP from the Dermopathology department, Hospital General Dr. Manuel Gea González. In 66 blocks from 63 patients, eosinophils were identified by hematoxylin and eosin staining, and mastocytes were labeled by immunohistochemistry. Three random microphotographs (40x) were used, and cell counts were calculated as the mean count in the 3 microphotographs., Results: Forty cases (63.5%) were female, and 23 (36.5%) were male. The mean age was 26.49 ±14.09 years; regarding the evolution time of the disease, the average was 11.93 years ±11.39. In 38 of 63 cases (60%), the lip, skin, and conjunctiva were affected clinically. In 22 of 63 cases (34%), AP cheilitis was the sole manifestation, and in 4 of 63 cases (6%), there were lesions in the skin and conjunctiva. The mean eosinophil count was 9 per case, the average number of mastocytes/field was 28.48 (range 0 to 66) Kruskal-Wallis p=0.001., Conclusions: There are elements in AP that mediate the reaction of hypersensitivity type IV b, necessitating the identification of triggering factors., Key Words: Actinic prurigo, eosinophil, hypersensitivity IV b, IgE, mastocytes.

Actinic prurigo is an idiopathic photodermatosis that affects the skin, as well as the labial and conjunctival mucosa in indigenous and mestizo populations of Latin America. It starts predominantly in childhood, has a chronic course, and is exacerbated with solar exposure. Little is known of its pathophysiology, including the known mechanisms of the participation of HLA-DR4 and an abnormal immunologic response with increase of T CD4+ lymphocytes. The presence of IgE, eosinophils, and mast cells suggests that it is a hypersensitivity reaction (likely type IVa or b). The diagnosis is clinical, and the presence of lymphoid follicles in the mucosal histopathologic study of mucosa is pathognomonic. The best available treatment to date is thalidomide, despite its secondary effects.

Background: Actinic prurigo (AP) is an idiopathic photodermatosis that usually onsets during childhood and predominates in women. It is characterized by the symmetrical involvement of sun-exposed areas of the skin, lips, and conjunctiva., Objectives: This study aimed to analyze the risk factors associated with AP using a case-control design., Methods: All patients diagnosed with AP during 1990-2006 at Dr. Manuel Gea González General Hospital in Mexico City were included. Respective controls were recruited. Race, demographic, geographic, socioeconomic, environmental, clinical, and nutritional risk factors were assessed., Results: A total of 132 persons were enrolled. These included 44 cases and two control groups comprising, respectively, dermatology and non-dermatology outpatients without AP or any autoimmune disease. Distribution by gender, age, place of birth, place of residence, and economic status did not differ significantly among the three groups. A total of 256 variables were analyzed. Only 19 variables were found to be statistically significant (P < 0.05). These were: use of a boiler; use of firewood; car ownership; use of earthenware; mixed material housing; socioeconomic level 1; sun exposure; use of soap; lemon consumption; use of moisturizing hair cream; living with pets in the house; living with farm animals; age; having a family member with AP; having had surgery; having had trauma; having been hospitalized; use of oral medication; and use of herbal medication. Of 40 macro- and micronutrients analyzed, 11 were found to have statistically significant effects (P < 0.05)., Conclusions: Multiple epidemiologic, geographic, clinical, and immunologic factors are involved in the etiology of AP. This study proposes a clear line for research directed at specific risk factors that refer to an individual's clinical, allergic, health, and socioeconomic status. Further study should also investigate the etiologic role of diet in AP and the molecular mechanisms behind the development of AP to establish whether AP is caused by exposure to polycyclic aromatic hydrocarbons., (© 2013 The International Society of Dermatology.)

Little is known about the residues that control the binding and affinity of thiazide-type diuretics for their protein target, the renal Na(+)-Cl(-) cotransporter (NCC). Previous studies from our group have shown that affinity for thiazides is higher in rat (rNCC) than in flounder (flNCC) and that the transmembrane region (TM) 8-12 contains the residues that produce this difference. Here, an alignment analysis of TM 8-12 revealed that there are only six nonconservative variations between flNCC and mammalian NCC. Two are located in TM9, three in TM11, and one in TM12. We used site-directed mutagenesis to generate rNCC containing flNCC residues, and thiazide affinity was assessed using Xenopus laevis oocytes. Wild-type or mutant NCC activity was measured using (22)Na(+) uptake in the presence of increasing concentrations of metolazone. Mutations in TM11 conferred rNCC an flNCC-like affinity, which was caused mostly by the substitution of a single residue, S575C. Supporting this observation, the substitution C576S conferred to flNCC an rNCC-like affinity. Interestingly, the S575C mutation also rendered rNCC more active. Substitution of S575 in rNCC for other residues, such as alanine, aspartate, and lysine, did not alter metolazone affinity, suggesting that reduced affinity in flNCC is due specifically to the presence of a cysteine. We conclude that the difference in metolazone affinity between rat and flounder NCC is caused mainly by a single residue and that this position in the protein is important for determining its functional properties.