Summary Background Scabies is a common parasitic skin condition that causes considerable morbidity globally. Clinical and epidemiological research for scabies has been limited by a lack of standardization of diagnostic methods. Objectives To develop consensus criteria for the diagnosis of common scabies that could be implemented in a variety of settings. Methods Consensus diagnostic criteria were developed through a Delphi study with international experts. Detailed recommendations were collected from the expert panel to define the criteria features and guide their implementation. These comments were then combined with a comprehensive review of the available literature and the opinion of an expanded group of international experts to develop detailed, evidence‐based definitions and diagnostic methods. Results The 2020 International Alliance for the Control of Scabies (IACS) Consensus Criteria for the Diagnosis of Scabies include three levels of diagnostic certainty and eight subcategories. Confirmed scabies (level A) requires direct visualization of the mite or its products. Clinical scabies (level B) and suspected scabies (level C) rely on clinical assessment of signs and symptoms. Evidence‐based, consensus methods for microscopy, visualization and clinical symptoms and signs were developed, along with a media library. Conclusions The 2020 IACS Criteria represent a pragmatic yet robust set of diagnostic features and methods. The criteria may be implemented in a range of research, public health and clinical settings by selecting the appropriate diagnostic levels and subcategories. These criteria may provide greater consistency and standardization for scabies diagnosis. Validation studies, development of training materials and development of survey methods are now required. What is already known about this topic? The diagnosis of scabies is limited by the lack of accurate, objective tests. Microscopy of skin scrapings can confirm the diagnosis, but it is insensitive, invasive and often impractical. Diagnosis usually relies on clinical assessment, although visualization using dermoscopy is becoming increasingly common. These diagnostic methods have not been standardized, hampering the interpretation of findings from clinical research and epidemiological surveys, and the development of scabies control strategies. What does this study add? International consensus diagnostic criteria for common scabies were developed through a Delphi study with global experts. The 2020 International Alliance for the Control of Scabies (IACS) Criteria categorize diagnosis at three levels of diagnostic certainty (confirmed, clinical and suspected scabies) and eight subcategories, and can be adapted to a range of research and public health settings. Detailed definitions and figures are included to aid training and implementation. The 2020 IACS Criteria may facilitate the standardization of scabies diagnosis.

Eumycetoma is caused by different fungi. Madurella mycetomatis, Madurella grisae, and Scedosporium apiospermum are the most common causative agents. This disease is more frequent on the lower extremities but can also be present in other areas. The diagnosis is made by direct microscopic examination and histologic study, which should show hyphae and vesicles characteristic of the fungi. Etiologic identification of the species of the fungus is sometimes difficult by culture and biopsy specimen; in these cases, molecular techniques can help to identify the infecting organism. Treatment has been with amphotericin B, which is now seldom used due to its side effects and limited success. The best therapeutic choice is surgical removal of the lesion, followed by medical treatment. This includes antifungals such as the azoles, ketoconazole and itraconazole; in resistant cases, posaconazole and voriconazole are currently recommended. In particular, the combination of terbinafine and itraconazole can elicit a good result in some cases.

The diagnosis of fungal Neglected Tropical Diseases (NTD) is primarily based on initial visual recognition of a suspected case followed by confirmatory laboratory testing, which is often limited to specialized facilities. Although molecular and serodiagnostic tools have advanced, a substantial gap remains between the desirable and the practical in endemic settings. To explore this issue further, we conducted a survey of subject matter experts on the optimal diagnostic methods sufficient to initiate treatment in well-equipped versus basic healthcare settings, as well as optimal sampling methods, for three fungal NTDs: mycetoma, chromoblastomycosis, and sporotrichosis. A survey of 23 centres found consensus on the key role of semi-invasive sampling methods such as biopsy diagnosis as compared with swabs or impression smears, and on the importance of histopathology, direct microscopy, and culture for mycetoma and chromoblastomycosis confirmation in well-equipped laboratories. In basic healthcare settings, direct microscopy combined with clinical signs were reported to be the most useful diagnostic indicators to prompt referral for treatment. The survey identified that the diagnosis of sporotrichosis is the most problematic with poor sensitivity across the most widely available laboratory tests except fungal culture, highlighting the need to improve mycological diagnostic capacity and to develop innovative diagnostic solutions. Fungal microscopy and culture are now recognized as WHO essential diagnostic tests and better training in their application will help improve the situation. For mycetoma and sporotrichosis, in particular, advances in identifying specific marker antigens or genomic sequences may pave the way for new laboratory-based or point-of-care tests, although this is a formidable task given the large number of different organisms that can cause fungal NTDs.

Onychomatricoma has a classical clinical appearance; however, it is difficult to identify, as it is not until surgery, when the typical filiform projections are more visible, that the diagnosis can be made. Onychomatricoma is a rare tumor. The involvement of the entire nail matrix, with secondary nail dystrophy, in both cases presented here makes them interesting case reports of this unusual form of tumor.

We report 73 cases of cutaneous sporotrichosis from the Community Dermatology program, at the central and mountain areas of the state of Guerrero, Mexico. A similar number of cases was found between children and adults, mostly peasants and school-age children with rural occupations. Upper limbs were the mostly affected and the predominant clinical form was lymphocutaneous (56.16%). All cultures corresponded to Sporothrix schenckii (sl). Treatment was done with potassium iodide in 54 patients, achieving clinical and mycological cure in all cases.