Background: Leprosy is a chronic, granulomatous, and infectious disease caused by Mycobacterium leprae and Mycobacterium lepromatosis. The diagnosis of the disease is primarily clinical based on the observation of the characteristic signs and symptoms. Laboratory tests such as bacilloscopy and skin biopsy can also be used to aid in diagnosis. Due to the lack of complementary tests with 100% sensitivity, diagnosis is often made based on the combination of clinical, laboratory, and molecular criteria. Although M leprae has a tropism for nerves, no validated minimally invasive procedure exists to sample nerves for this disease. The investigation of the genetic material of the etiological agents that cause leprosy through perineural collection guided by ultrasound is a promising method for improving diagnostic accuracy. Objective: This study aims to evaluate the accuracy of ultrasound-guided perineural aspirate in the diagnosis of leprosy. The World Health Organization leprosy composite reference standard will be used as the benchmark for diagnostic accuracy. We will also perform the clinical, molecular, and ultrasonographic follow-up of patients. The study will be performed at the University Hospital of Brasília, a reference center for the treatment of leprosy in the central-west region of Brazil. Methods: This will be a diagnostic study with consecutive prospective recruitment of patients referred to the leprosy outpatient clinic of University Hospital of Brasília for diagnosis and treatment. During follow-up, clinical and molecular examinations will be performed, and their results will be compared to the sonographic findings, which will be collected monthly for 1 year. Patients will be evaluated clinically, via ultrasound, and molecularly in 2 stages of leprosy diagnosis and treatment: immediately after clinical diagnosis and 1 year after the start of treatment. Subcutaneous aspiration of the ulnar nerve will be performed in the ulnar tunnel guided by ultrasound. The aspirated material will be used for identification of bacillary DNA and RNA at the time of diagnosis and 1 year after the start of treatment. Results: Grant funding for this study was received in May 2023, August 2023, and June 2026. As of October 2025, no patients have been enrolled in this study. Patient recruitment started in January 2026 and is expected to be concluded in December 2026. Collection of clinical and laboratorial data will follow the same schedule as that of recruitment. Analysis of the collected data will be conducted between February 2027 and July 2027, with results expected to be submitted to publication by August 2027. Conclusions: We believe that ultrasound-guided perineural aspirate will increase the accuracy of leprosy diagnosis and may demonstrate the viability of the bacillus before and after treatment via RNA identification. International Registered Report Identifier (IRRID): PRR1-10.2196/86421

Background/Objectives: American Tegumentary leishmaniasis typically presents as a single ulcerative lesion, but atypical clinical forms exist with diverse physiopathology and treatment responses. Disseminated cutaneous leishmaniasis is a less common presentation that is often challenging to treat and for which evidence-based clinical decisions are scant. A better understanding of treatment response may support the development of alternative therapeutic strategies. This study reports a retrospective cohort analysis using a time-to-event outcome to compare disseminated leishmaniasis with localized cutaneous leishmaniasis using a multivariate model. Methods: A total of 366 patients were screened for inclusion between 2014 and 2024, of whom 123 met the inclusion criteria. Results: After adjustment for age and sex, patients with disseminated cutaneous leishmaniasis had a significantly longer time to healing than those with localized cutaneous leishmaniasis (HR = 0.29; p = 0.021). Conclusions: Disseminated cutaneous leishmaniasis seems to be an important predictor of poorer clinical outcomes with prolonged healing time. New therapeutic strategies are urgently needed to address this issue.

BACKGROUND Leprosy is a chronic, granulomatous, and infectious disease caused by Mycobacterium leprae and Mycobacterium lepromatosis. The diagnosis of the disease is primarily clinical based on the observation of the characteristic signs and symptoms. Laboratory tests such as bacilloscopy and skin biopsy can also be used to aid in diagnosis. Due to the lack of complementary tests with 100% sensitivity, diagnosis is often made based on the combination of clinical, laboratory, and molecular criteria. Although M leprae has a tropism for nerves, no validated minimally invasive procedure exists to sample nerves for this disease. The investigation of the genetic material of the etiological agents that cause leprosy through perineural collection guided by ultrasound is a promising method for improving diagnostic accuracy. OBJECTIVE This study aims to evaluate the accuracy of ultrasound-guided perineural aspirate in the diagnosis of leprosy. The World Health Organization leprosy composite reference standard will be used as the benchmark for diagnostic accuracy. We will also perform the clinical, molecular, and ultrasonographic follow-up of patients. The study will be performed at the University Hospital of Brasília, a reference center for the treatment of leprosy in the central-west region of Brazil. METHODS This will be a diagnostic study with consecutive prospective recruitment of patients referred to the leprosy outpatient clinic of University Hospital of Brasília for diagnosis and treatment. During follow-up, clinical and molecular examinations will be performed, and their results will be compared to the sonographic findings, which will be collected monthly for 1 year. Patients will be evaluated clinically, via ultrasound, and molecularly in 2 stages of leprosy diagnosis and treatment: immediately after clinical diagnosis and 1 year after the start of treatment. Subcutaneous aspiration of the ulnar nerve will be performed in the ulnar tunnel guided by ultrasound. The aspirated material will be used for identification of bacillary DNA and RNA at the time of diagnosis and 1 year after the start of treatment. RESULTS Grant funding for this study was received in May 2023, August 2023, and June 2026. As of October 2025, no patients have been enrolled in this study. Patient recruitment started in January 2026 and is expected to be concluded in December 2026. Collection of clinical and laboratorial data will follow the same schedule as that of recruitment. Analysis of the collected data will be conducted between February 2027 and July 2027, with results expected to be submitted to publication by August 2027. CONCLUSIONS We believe that ultrasound-guided perineural aspirate will increase the accuracy of leprosy diagnosis and may demonstrate the viability of the bacillus before and after treatment via RNA identification. INTERNATIONAL REGISTERED REPORT PRR1-10.2196/86421