Differential expression of TOB/BTG family members in patients with plaque psoriasis: cross-sectional study.

TOB/BTG is a family of antiproliferative proteins that play an important role in the regulation of immune responses, acting as lymphocyte activators and macrophage-mediated cytotoxicity. No previous studies have explored their role in patients with psoriasis. The aim of this study was to characterize the expression of TOB/BTG family and their co-localization in skin from patients with psoriasis. This is an exploratory, observational, and cross-sectional study that included 24 plaque psoriasis patients and 15 controls. Gene expression of TOB/BTG family was determinate by RT-PCR. Protein products of TOB/BTG were evaluated by immunohistochemistry and compared with control skin tissues. Holm-Sidak's multiple comparisons test was performed. TOB/BTG family mRNA levels and protein expression were significantly decreased in psoriatic skin tissue compared to non-inflammatory control skin tissue. Double-positive cell TOB1/2, BTG1,2 and BTG4/CD16 expressions were found in normal control skin tissues through epidermis and dermis (p < 0.001) and lesser percentage in patients with mild, almost absent in moderate-severe plaque psoriasis. This is the first report of the TOB/BTG family gene and protein expression in skin tissues by a CD16 + subpopulation in plaque psoriasis. TOB/BTG family protein might represent a new therapeutic target among immune-mediated inflammatory diseases.

Interleukin-17 and Tumor Necrosis Factor Show a Functional Hierarchy to Regulate the Production of Matrix Metalloproteases by Monocytes from Patients with Psoriasis.

Interleukin-17 (IL-17) and tumor necrosis factor (TNF) regulate tissue remodeling through matrix metalloproteinases (MMPs). It is not yet clear whether these cytokines have a functional hierarchy in psoriasis. Serum levels of TNF (1,403 versus 1,058 pg/mL), IL-17 (1,528 versus 820 pg/mL), MMP-1 (1,999 versus 1,039 pg/mL), and MMP-9 (1,950 versus 1,561 pg/mL) were higher in psoriasis subjects (n = 60) than in control subjects (n = 60). Tissue inhibitor of MMPs (TIMP-1; 1,374 versus 1,218 pg/mL) was lower in psoriasis subjects. Serum IL-17 was correlated with MMP-2 (rs = 0.40) and TIMP-1 (rs = -0.26) levels. Unstimulated production of MMP-1, MMP-2, and MMP-9 by monocytes was higher in psoriasis subjects, whereas TIMP-1 production was lower. TNF stimulation increased all MMPs, whereas TIMP-1 production was unchanged. IL-17 stimulation increased all MMPs, whereas TIMP-1 production was decreased in psoriasis subjects. MMP-9 production was higher in monocytes stimulated with IL-17 compared with TNF. TIMP-1 production was decreased more by IL-17 than by TNF, but only in psoriasis cells. MMP-1/TIMP-1, MMP-2/TIMP-1, and MMP-9/TIMP-1 ratios were higher after IL-17 stimulation (compared with TNF stimulation) in psoriasis subjects; this occurred in controls only for the MMP-2/TIMP-1 ratio. IL-17 has a greater ability than TNF to dysregulate the MMPs/TIMP-1 balance, supporting IL-17 blockade as first-line treatment in cutaneous psoriasis.

Enfermedad de Paget pigmentada de la mama simuladora de melanoma cutáneo / Pigmented mammary Paget's disease mimicking cutaneous melanoma

Resumen ANTECEDENTES: La enfermedad de Paget pigmentada de la mama es una variante poco frecuente de este padecimiento cutáneo, una dermatosis que afecta al complejo areola-pezón de manera típicamente unilateral. La importancia del reconocimiento de esta dermatosis pigmentada inespecífica es que forma parte del diagnóstico diferencial del melanoma cutáneo, por manifestarse como una mácula pigmentada irregular, cuyo estudio histopatológico muestra una proliferación de melanocitos en los estratos suprabasales de la epidermis, fagocitosis de melanina y melanófagos en dermis, hallazgos muy similares al melanoma cutáneo, además de la coexistencia de células claras malignas, características de la enfermedad de Paget. La inmunohistoquímica es una técnica auxiliar en la dermatopatología, que forma parte del proceso diagnóstico de los pacientes para lograr el diagnóstico certero que, al correlacionar la clínica y el estudio histopatológico, le permite al dermatólogo tratar a los pacientes con enfermedad de Paget pigmentada de la mama junto con un equipo multidisciplinario para la búsqueda, diagnóstico y, en su caso, tratamiento quirúrgico de las neoplasias subyacentes que suelen relacionarse con esta variante pigmentada. CASO CLÍNICO: Paciente de 35 años con una lesión pigmentada que afectaba el complejo areola-pezón derecho. Con la correlación histopatológica e inmunohistoquímica se estableció el diagnóstico de enfermedad de Paget pigmentada de la mama y posterior al procedimiento ginecológico, se asoció esta dermatosis con un adenocarcinoma microinvasor triple negativo. CONCLUSIONES: La enfermedad de Paget pigmentada de la mama es un diagnóstico complejo que requiere correlación clínico-patológica y estudios de extensión para valorar su asociación con neoplasias subyacentes.

Abstract BACKGROUND: Pigmented Mammary Paget's Disease is a rare variant of this skin condition, an unilateral dermatosis that typically affects the areola-nipple complex. The importance of recognizing this nonspecific pigmented dermatosis resides in its differential diagnosis of cutaneous melanoma, as it presents as an irregular pigmented macula. The histopathological study shows proliferation of melanocytes in the suprabasal layers of epidermis, phagocytosis of melanin and melanophages in dermis. These findings are very similar to cutaneous melanoma, in addition to the presence of malignant clear epitelial cells that are characteristic of Paget's disease. Immunohistochemistry is part of the approach of patients with lesions that shows proliferating melanocytes to rule out other neoplasms. Making an accurate diagnosis by correlating the clinical, histopathological study and immunohistochemistry allows the dermatologist to approach patients with mammary pigmented mammary Paget's disease with a multidisciplinary team for the diagnosis and surgical treatment of the underlying neoplasms that are usually related to this pigmented variant. CASE REPORT: We report the case of a 35 years old woman with a pigmented lesion that affected the right areola-nipple complex. With the histopathological and immunohistochemical correlation, the diagnosis of pigmented mammary Paget's disease was made and after the gynecological approach, this dermatosis was associated with a triple negative microinvasive adenocarcinoma. CONCLUSION: Pigmented mammary Paget's disease is a complicated diagnosis that requires clinicopathological correlation and extension studies to assess its association to underlying neoplasms.

Leprosy Caused by Mycobacterium lepromatosis.

OBJECTIVES: Leprosy is caused by Mycobacterium leprae or Mycobacterium lepromatosis. This study reviews literature on M lepromatosis and reports on a Mexican family with this infection. METHODS: The review included all primary studies. Family history and surveys were used to uncover the infection cluster. Genome-based differential polymerase chain reactions were designed to detect etiologic agents. RESULTS: Since the discovery of M lepromatosis in 2008, 154 cases of M lepromatosis infection from 11 countries in the Americas and Asia have been reported, with most cases coming from Mexico. These cases included diffuse lepromatous leprosy (DLL) and other leprosy forms. Genomes of M lepromatosis strains have lately been sequenced, revealing 3,271,694 nucleotides and approximately 15% mismatches with M leprae. The Mexican family with leprosy involved the grandfather, mother, and 2 grandsons. The index was the oldest grandson, who manifested DLL and likely contracted the infection from his maternal grandfather approximately 13 years earlier. Family surveys diagnosed DLL in the index patient's mother and borderline leprosy in his brother; both were likely infected by the index patient. M lepromatosis was identified from archived biopsies from the index patient and his mother, while M leprae was excluded. CONCLUSIONS: M lepromatosis is a significant cause of leprosy in Mexico and requires better surveillance and control.

Ungual Spitz Nevus: Description of Dermoscopic Data.

Introduction: Spitz nevus is an uncommon, benign melanocytic proliferation that primarily appears on face, trunk or lower extremities of children. This lesion may share clinical and microscopical characteristics with melanoma, making it a diagnostic and management challenge. Case Report: A 13-year old male presented with an asymptomatic chronic dermatosis located on the third left-hand nail. Cutaneous examination revealed a homogeneous dark brown melanonychia which extended up to the cuticle. Upon dermoscopy, longitudinal bands measuring less than 3 mm wide of heterogeneous colors ranging from light to dark brown, and positive Hutchinson's sign were observed. Discussion/Conclusion: We report the second case of a Spitz nevus ungually localized which strongly resembled an ungual melanoma with a positive Hutchinson's sign upon dermoscopy. Describing the infrequent presentation and location of the Spitz nevus poses an opportunity to establish diagnostic and management criteria in the near future.

Neurofibromatosis segmentaria, a propósito de un caso / Segmental neurofibromatosis, case report

Resumen Introducción: la neurofibromatosis es un desorden genético, que afecta el crecimiento de tejidos neurales, con una incidencia de 1 en 4 000 personas, con impacto en la esperanza de vida por su asociación con neoplasias y enfermedad vascular. La neurofibromatosis segmentaria es una variante de la neurofibromatosis tipo 1, con una incidencia aproximada de 1 en 20 000 a 25,000 personas, se caracteriza por lesiones cutáneas que afectan un segmento corporal sin cruzar la línea media. Generalmente no tienen historia familiar ni compromiso sistémico. Caso clínico: paciente de sexo femenino de 63 años con dermatosis que afecta el tronco posterior de manera unilateral a nivel de los dermatomas T10-T11, caracterizada por múltiples neoformaciones exofíticas milimétricas en forma de domo, de consistencia blanda y depresibles a la palpación. El estudio histopatológico de una de ellas confirmó el diagnóstico de neurofibroma. La paciente no presentaba afectación neurológica ni ocular, además, sin afección en familiares, por lo que se establece diagnóstico de neurofibromatosis segmentaria. Conclusiones: la neurofibromatosis segmentaria es una patología poco frecuente, Aunque posiblemente sea subdiagnosticada por su carácter asintomático, lo que ocasiona una aparente baja incidencia. Los pacientes que la padecen pueden presentar penetrancia sistémica variable y un riesgo similar de neoplasias al descrito en pacientes con neurofibromatosis tipo 1. Pese al carácter benigno reportado en la literatura sugerimos un abordaje multidisciplinario de los pacientes.

Abstract Introduction: neurofibromatosis is a genetic disorder that affects the growth of neural tissues, with an incidence of 1 in 4 000, with impact on life expectancy due its association with neoplasms and vascular disease. segmental neurofibromatosis is a subtype of neurofibromatosis type 1, with an approximate incidence of 1 in 20 000 to 25 000 people, it is characterized by skin lesions that affects a body segment without crossing midline, they generally have no family history or systemic involvement. Clinical case: a 63-year-old female patient with dermatosis affecting the posterior trunk unilaterally at the level of dermatomes t10-t11, characterized by multiple exophytic, dome-shaped, millimeter sized neoformations, soft in consistency and depressible on palpation. the histopatologic study of one of them confirmed the diagnosis of neurofibroma. the patient did not present neurological or ocular involvement, without affection in relatives. diagnosis of segmental neurofibromatosis was made. Conclusions: segmental neurofibromatosis is a rare pathology, although it is possibly underdiagnosed due its asymptomatic nature, which causes an apparent low incidence. patients may present variable systemic penetrance and a similar risk of neoplasm compared to patients with neurofibromatosis type 1. despite the benign nature reported in the literature, we suggest a multidisciplinary approach to patients.

Utility of IgG4 immunohistochemistry detection in pemphigus diagnosis.

Pemphigus includes a group of blistering autoimmune diseases that affect the skin and mucosa, characterized by the formation of epidermal bullous and the presence of antibodies against binding proteins. Pemphigus is classified according to clinical presentation, target molecule, and IgG production as pemphigus vulgaris, foliaceous, IgA-pemphigus, and paraneoplastic pemphigus. Thus, the identification of autoantibodies class and site of deposition is mandatory. The gold standard to identify the immune complex deposition is the direct immunofluorescences technique, performed in fresh tissue; unfortunately, this method is unavailable in the regional hospital at the Mexican provinces. Nevertheless, IgG subclass-4 is the prevalence of immunoglobulin in acantholysis. Therefore, this IgG subclass could be detected using IgG4 immunohistochemistry. Because direct immunofluorescences technique is absent in provinces or patients denied a new biopsy to confirm the diagnosis, this work presented pemphigus vulgaris confirmation using the IgG4 immunohistochemistry technique in patients with clinical lesions suggestive of pemphigus vulgaris and intraepidermal blister manifestation in histopathology.

Dermatosis en la región mamaria: estudio retrospectivo de 171 pacientes atendidas en el Hospital General Dr. Manuel Gea González / Skin diseases of the breast: A retrospective study of 171 patients at "Dr. Manuel Gea González" General Hospital

Resumen OBJETIVO: Describir las dermatosis de la región mamaria que para su diagnóstico durante la consulta dermatológica ameritaron estudio histopatológico. MATERIALES Y MÉTODOS: Estudio retrospectivo llevado a cabo con base en los expedientes electrónicos de pacientes atendidas en el servicio de Dermatopatología entre 1992 y 2021. Los términos de búsqueda fueron: "mama", "seno", "areola" y "pezón". RESULTADOS: Se reunieron 171 reportes histopatológicos. El diagnóstico clínico de envío más común en mujeres fue la infiltración cutánea por cáncer de mama y en hombres el pezón supernumerario. Las dermatosis más frecuentes pertenecieron al grupo de tumoraciones benignas (78 de 171), seguidas de las dermatosis inflamatorias no infecciosas (48 de 171), en tercer lugar las neoplasias malignas (39 de 171) y 6 de 171 correspondieron a dermatosis inflamatorias infecciosas. CONCLUSIONES: Las enfermedades cutáneas de la mama tienen diversas manifestaciones clínicas que, en ocasiones, ameritan un estudio histopatológico, sobre todo para un diagnóstico oportuno de neoplasias malignas.

Abstract OBJECTIVE: Describe dermatoses of the mammary region that warranted histopathological diagnosis in dermatologic consults. MATERIALS AND METHODS: The Hospital "Dr. Manuel Gea Gonzalez" Dermatopathology Department record database was reviewed in the 1992 to 2021 period, using the search engine terms "breast," "mammary," "nipple," and "areola." Lesions were classified as benign, malignant, infectious and noninfectious inflammatory tumors. RESULTS: 171 histopathological reports were reviewed. There was a female predominance in histopathological studies (153/171). The most frequent clinical diagnosis for referral in female patients was breast cancer with cutaneous infiltration; supernumerary nipple was the most frequent clinical diagnosis for male patients. The most frequent dermatoses belonged to the benign tumor category (78/171), followed by noninfectious inflammatory dermatoses (48/171). Malignant neoplasms were in third place (39/171), and 3.5% of dermatoses were infectious inflammatory dermatoses. CONCLUSIONS: Cutaneous mammary disease has diverse clinical presentations that might occasionally warrant histopathological studies, mainly for the early diagnosis of malignant neoplasms.

Disseminated and recurrent infundibulofolliculitis in children in Mexico.

Disseminated and recurrent infundibulofolliculitis is an uncommon non-infectious skin eruption characterized by recurrent, sometimes pruritic, follicular papules commonly seen on the trunk and proximal extremities. We describe the clinical, dermoscopic, and histopathologic characteristics of disseminated and recurrent infundibulofolliculitis in three young pediatric patients from the tropical regions of Mexico, Guerrero, and Chiapas.

Value of the toluidine blue test as an aid to determine the biopsy site in actinic prurigo cheilitis.

Actinic prurigo (AP) is a type of photodermatosis that primarily affects the Latin American mestizo population. Histologically, AP cheilitis exhibits acanthosis with spongiosis and vacuolation of the basal cell layer overlying a dense lymphocytic inflammatory infiltrate that forms well-defined lymphoid follicles. Toluidine blue is a thiazide, acidophilic, and metachromatic dye used in vivo to selectively stain the acidic components of tissues such as sulfates, carboxylates, and phosphate radicals that are incorporated into DNA and RNA. It is necessary to develop a method that allows detecting, on clinical grounds the area of the lesion in which it is more feasible to find such structures. Thus to increase the sensitivity of the biopsy, in AP cheilitis to accurately identify where the lymphoid follicles reside, based on the higher concentration of DNA in such structures and thus confirm the diagnosis. In this study, staining was positive in 85% of patients with AP cheilitis, in 14 of whom 82% lymphoid follicles were observed by histopathology. One of the pathologist's problems in establishing the diagnosis of AP is that the main histopathological characteristics are not always identified in the submitted samples because it is not easy to clinically identify the most representative site of the lesion selected for performing a biopsy. Based on our results, we propose using toluidine blue as an auxiliary method to choose a tissue sample to facilitate the diagnosis and allow clinicians to make clinical correlations between the histopathological and therapeutic findings.

Pseudoxanthoma Elasticum: Report of Two Cases.

Elastic pseudoxanthoma is a rare disease with autosomal recessive inheritance, also known as Grönblad-Strandberg syndrome, characterized by pathological mineralization of the elastic fibers in the connective tissue, affecting principally the dermis of skin, media, and intima of blood vessels and Bruch's membrane of the eye. The genetic defect of the disorder is located on chromosome 16p13.1 and disease is caused by the lack of functional ABCC6 protein, which in turn causes extracellular accumulation and deposition of calcium and other minerals in the elastic tissue. In this article we present two cases of this rare disease. We emphasize, in the diagnostic criteria, the importance of its early diagnosis and the current therapeutic approaches.

Subclinical Onychomycosis in Apparently Healthy Adults.

INTRODUCTION: Onychomycosis is a frequent chronic nail infection, with a worldwide prevalence of 5.5% making it the most common nail disease, and its incidence increases with age. Clinically, it causes discoloration and thickening of the nail plate and may be accompanied by onycholysis. However, little is known of the subclinical infection. METHODS: We studied adult male and female outpatients auto-referred as healthy and that had healthy appearing toenails. Nail distal clippings were obtained from the right first toenail. This sample was stained with PAS and observed by an expert dermatopathologist searching for fungal structures. RESULTS: A total of 32 samples were included: 8 from men (25%) and 24 from women (75%), with ages ranging from 27 to 66 years (mean age of 43 years). Twenty-four patients did not present any histopathological finding suggestive of infection (75%), while 7 patients had a single finding (spores or hyphae) (21.8%), and 1 patient had both findings (3.12%). DISCUSSION/CONCLUSION: We found 4 patients with yeasts, 3 with hyphae, and 1 patient with a combined infection with both yeasts and hyphae (3.1%). These add up to 25% of the clinically apparent healthy nails. Our results show that we still have much to learn from the initial stages of onychomycosis and that our population probably has higher incidence of this nail disease, so we must be alert to subtle nail changes. As our participants signed an informed consent, we will contact those that resulted positive for follow up consultations.

Cutaneous manifestations of COVID-19 in Mexican patients: A case series and review of literature.

China officially recognized atypical pneumonia outbreak in December 2019; on 11 March 2020, the World Health Organization declared COVID-19 as a pandemic that is produced by a new coronavirus, named SARS-CoV-2, of rapid transmissibility, which can be asymptomatic, with mild to severe respiratory symptoms, and with cardiovascular, neurological, gastrointestinal, and cutaneous complications. Considering that the pandemic prolonged more than initially expected was prognostic, it is essential for the medical community to identify the signs and symptoms of COVID-19. Thus, this work's objectives were to present cases of cutaneous lesions observed in COVID-19 Mexican patients. We register cutaneous lesions in COVID-19 patients referred from internal medicine and otorhinolaryngology services to dermatology. We presented four interesting cases with cutaneous lesions, including exanthema morbilliform, urticaria, chilblains, ecchymosis, and facial edema, and review the available literature. The most frequent cutaneous markers are rash, chilblains, and urticaria. Skin lesions may be the first manifestation of COVID-19, accompany initial respiratory symptoms, or appear during the disease course. Symptoms associated with vascular changes (livedo reticularis and vasculitis) are considered of poor prognosis.

Value of the toluidine blue test as an aid to determine the biopsy site in actinic prurigo cheilitis

Actinic prurigo (AP) is a type of photodermatosis that primarily affects the Latin American mestizo population. Histologically, AP cheilitis exhibits acanthosis with spongiosis and vacuolation of the basal cell layer overlying a dense lymphocytic inflammatory infiltrate that forms well-defined lymphoid follicles. Toluidine blue is a thiazide, acidophilic, and metachromatic dye used in vivo to selectively stain the acidic components of tissues such as sulfates, carboxylates, and phosphate radicals that are incorporated into DNA and RNA. It is necessary to develop a method that allows detecting, on clinical grounds the area of the lesion in which it is more feasible to find such structures. Thus to increase the sensitivity of the biopsy, in AP cheilitis to accurately identify where the lymphoid follicles reside, based on the higher concentration of DNA in such structures and thus confirm the diagnosis. In this study, staining was positive in 85% of patients with AP cheilitis, in 14 of whom 82% lymphoid follicles were observed by histopathology. One of the pathologist's problems in establishing the diagnosis of AP is that the main histopathological characteristics are not always identified in the submitted samples because it is not easy to clinically identify the most representative site of the lesion selected for performing a biopsy. Based on our results, we propose using toluidine blue as an auxiliary method to choose a tissue sample to facilitate the diagnosis and allow clinicians to make clinical correlations between the histopathological and therapeutic findings.

Human skin biomarkers relationship to response to treatment with tyrosine kinase inhibitors in advanced EGFR-mutated lung adenocarcinoma.

BACKGROUND: A relationship between the EGFR signaling pathway expression in skin and the use of targeted cancer therapies has been previously demonstrated. Consistent evidence to support the use of skin biopsies as a surrogate for therapeutic evaluation is needed. The purpose of this study was to establish the relationship between the expression of EGFR signaling pathway markers in skin samples from EGFR-mutated metastatic lung adenocarcinoma patients and their response to tyrosine kinase inhibitors. METHODS: This was a prospective single blind analysis of 35 skin biopsies from 31 patients with confirmed advanced EGFR-mutated lung adenocarcinoma. Immunohistochemistry was performed: EGFR, p27, Ki67, STAT3 and MAPK, as well as H&E histopathological analysis, in order to determine their treatment response to tyrosine kinase inhibitors. RESULTS: EGFR, Ki67, STAT3, stratum corneum thickness (number of layers and millimeters) from skin samples had a statistical correlation with an adequate treatment response (P = 0.025, 0.015, 0.017, 0.041, 0.039 respectively). EGFR, p27 and number of layers of the stratum corneum were related to a better median progression-free survival (P = 0.025 and P = 0.030). CONCLUSIONS: The relationship between EGFR pathway inhibition in the skin and oncological outcomes obtained explains the parallel biological effects of tyrosine kinase inhibitors. We hope that our work incites future research to help validate and assess the use of these markers as potential prognostic and predictive factors.

Alopecia Secondary to Hyaluronic Acid Embolization: Trichoscopic Findings.

Fillers are frequently used in aesthetic medicine and, although usually safe, complications can occur. Vascular occlusion leading to tissue necrosis is a rare but severe complication. Alopecia after hyaluronic acid injection has been recently reported, being a vascular compromise the most probable physiopathological mechanism. The trichoscopic findings in this entity have not been described yet. A case report of a 30-year-old female who developed this complication following a hyaluronic acid injection as well as the description of the trichoscopic findings are presented in this report.

Trypanosoma cruzi infection associated with atypical clinical manifestation during the acute phase of the Chagas disease.

BACKGROUND: Chagas disease (CD) is caused by the protozoan parasite Trypanosoma cruzi and is transmitted by triatomine insects. Clinical manifestations vary according to the phase of the disease. Cutaneous manifestations are usually observed in the acute phase (chagoma and Romaña's sign) or after reactivation of the chronic phase by immunosuppression; however, a disseminated infection in the acute phase without immunosuppression has not been reported for CD. Here, we report an unusual case of disseminated cutaneous infection during the acute phase of CD in a Mexican woman. METHODS: Evaluation of the patient included a complete clinical history, a physical exam, and an exhaustive evaluation by laboratory tests, including ELISA, Western blot and PCR. RESULTS: Skin biopsies of a 50-year-old female revealed intracellular parasites affecting the lower extremities with lymphangitic spread in both legs. The PCR tests evaluated biopsy samples obtained from the lesions and blood samples, which showed a positive diagnosis for T. cruzi. Partial sequencing of the small subunit ribosomal DNA correlated with the genetic variant DTU II; however, serological tests were negative. CONCLUSIONS: We present a case of CD with disseminated skin lesions that was detected by PCR and showed negative serological results. In Mexico, an endemic CD area, there are no records of this type of manifestation, which demonstrates the ability of the parasite to initiate and maintain infections in atypical tissues .

Myiasis caused by Dermatobia hominis in Mexico: morphological and molecular identification using the cytochrome oxidase I gene.

Myiasis caused by Dermatobia hominis , the human botfly, is frequent in the Americas, however, scarce morphological and molecular information exist regarding this dipteran. We describe three cases in urban areas of Mexico were D. hominis is not endemic. Morphological and genetic identification were performed using the cytochrome oxidase I as a molecular marker. The mitochondrial cytochrome oxidase I gene is useful for inferring the genetic divergence of D. hominis .