‘Wake sign’: an important clue for the diagnosis of scabies

Dermoscopic and reflectance confocal microscopic features of children scabies

OBJECTIVE

To summarize the image features of dermatoscopy and reflectance confocal microscopy (RCM) in children with scabies, and to explore the clinical significance in the diagnosis of children scabies.

METHODS

A retrospective analysis was conducted on 102 children scabies diagnosed clinically in the dermatology outpatient department of Tianjin Children's Hospital from April 2018 to June 2022. All children were examined by dermatoscopy and RCM, and images were collected.

RESULTS

102 patients, 92 patients (90.2%) showed characteristic dermoscopic manifestations: white tunnels and small brown or dark brown triangular structures at their ends. 91 patients (89.2%) showed characteristic reflectance confocal microscopic manifestations: tunnels, scabies mites, feces, and eggs in the epidermal layer. All patients showed different degrees of non-specific manifestations of dermoscopy and RCM.

CONCLUSION

Children scabies have typical dermatoscopic and reflectance confocal microscopic characteristics, and dermatoscopy and RCM are effective non-invasive diagnostic methods with high clinical application value in the diagnosis and differential diagnosis of children scabies.

Facilitations in the Clinical Diagnosis of Human Scabies through the Use of Ultraviolet Light (UV-Scab Scanning): A Case-Series Study

BACKGROUND

To confirm the suspicion of scabies, dermatologists have one pathognomonic sign, "the tunnel" through which Sarcoptes scabiei digs into the epidermis. Light microscopy is considered the most reliable procedure, but it is time-consuming and operator-dependent. Recently, dermoscopy has greatly improved the chances of recognizing mite in situ, but it is still linked to the examiner's experience and to the magnification capability of the device used.

METHODS

This article, based on a case-series study, describes a novel diagnostic path, which uses an ultraviolet LED source at 365 nm and a digital camera for the evaluation of lesions that raise the suspicion of scabies.

RESULTS

The gallery emits a naked-eye-visible wavy bluish-white linear luminescence, better than that of any standard lighting. UVA light is also able to identify Sarcoptes scabiei as a white or green point-shaped area. This sign can only be appreciated by enlarging its picture to full frame on a common PC monitor.

CONCLUSIONS

Ultraviolet light (365 nm) seems to offer help in the diagnosis of scabies because it saves time compared with light microscopy and because it does not require contact with the patient's skin, as in dermoscopy. Although examiner experience remains an important factor, it is easily compensated by procedural simplicity, the cost of the devices and, especially, by the clarity of the results, even in non-specific lesions.

The unsung signs of dermatology

“The eye sees only what the mind is prepared to comprehend.”

The term “sign” refers to an objective physical finding observed by the examiner. In dermatology, the diagnosis mainly depends on the examiner and certain physical signs serve as an important clue to diagnosis of the disease. The objective of this review is to bring to light certain lesser-known signs in dermatology.

The 2020 International Alliance for the Control of Scabies Consensus Criteria for the Diagnosis of Scabies

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.

Gray-edged line sign of scabies burrow

A scabies burrow is created by a mature female mite laying eggs through the stratum corneum, representing a kind of scabies eruption. We have noticed that the edges of the scabies burrow sometime appear as blackish-gray lines. We named these lines the "gray-edged line" sign, as a new feature of scabies burrows. The gray-edged line sign has the following two tendencies: (i) it is rarely seen on the palm or sole; and (ii) when the burrow follows a curved course, the gray-edged line often forms on the outer wall. Explaining the formation of this sign from clinical findings was difficult, so the aim of the present study was to elucidate the mechanisms underlying the gray-edged line sign. This retrospective study involved collection of data from electronic medical records of patients treated for scabies in our department between April 2015 and February 2020. We treated 32 scabies patients, including 4 patients with the gray-edged line sign. We analyzed clinical features, dermoscopy, histopathology and special stains. Fontana-Masson staining showed melanin staining in three parts: feces; some keratinocytes around the scabies burrows; and the mouth and legs of the scabies mite. The gray-edged line sign appears to represent mite feces containing melanin.

Scabies: A comprehensive review and current perspectives

Human scabies is a contagious skin infestation caused by the parasitic mite Sarcoptes scabiei var. hominis. It is a common skin disease worldwide that occurs not only in the underprivileged sections of society but also in developed countries. In 2009, World Health Organization (WHO) recognized scabies as "neglected tropical disease (NTD)" or NTD thus emphasizing the need for community awareness and proper treatment strategies. This review attempts to summarize the varied clinical presentation of the disease and describes the advances in diagnosis and management including the ongoing search for novel agents to overcome the problems associated with conventional treatments. The literature research includes peer-reviewed articles (clinical trials or scientific reviews). Studies were identified by searching electronic databases (MEDLINE and PubMed) till February 2020 and reference lists of respective articles. Only articles published in English language were included.

In Situ Diagnosis of Scabies Using a Handheld Digital Microscope in Resource-Poor Settings-A Proof-of-Principle Study in the Amazon Lowland of Colombia

Scabies is a neglected tropical disease associated with important morbidity. The disease occurs worldwide and is particularly common in resource-poor communities in the Global South. A validated technique for the diagnosis of scabies in resource-poor settings does not exist. The objective of the study was to determine the practicability and accuracy of handheld digital microscopy in three indigenous communities in the Amazon lowland of Colombia, where scabies is the most common parasitic skin disease. One-hundred-and-eleven children and adults from three indigenous communities with a presumptive diagnosis of scabies were examined clinically by using a handheld digital microscope placed directly on the skin. The microscopical identification of a mite was verified by an "experienced mother", a woman who had acquired the skills to diagnose scabies as part of traditional Amerindian medicine. The "experienced mother" removed the parasite with a fine needle and placed it on a flat surface in order to enable its direct examination with the digital microscope. Using digital microscopy, scabies was diagnosed in 24 out of 111 participants and confirmed by the extraction of a Sarcoptes mites from the acarine eminence. A characteristic tunnel (burrow) with or without mite could be clearly identified irrespective of the degree of pigmentation of the skin. Besides, digital microscopy revealed pathological characteristics of scabies hitherto unknown and impossible to be seen in dermoscopy, such as partially or totally obliterated tunnels, tunnels with multiple entry or exit points, circumscribed hyperpigmentation around obliterated tunnels and mites secluded in a nodule. This proof-of-principle study demonstrated the accurate diagnosis of scabies by handheld digital microscopy in patients with pigmented skin and the feasibility of this technique in resource-poor settings.

Impaired quality of life in adults and children with scabies from an impoverished community in Brazil

BACKGROUND

Scabies is highly prevalent in resource-poor communities in developing countries and is associated with considerable morbidity in this setting. How the parasitic skin disease impairs the quality of life of patients has rarely been investigated.

METHODOLOGY

A modified Dermatology Life Quality Index (mDLQI) was developed to assess the quality of life in adults and children with scabies living in an urban slum in Fortaleza, capital of Ceará State, Brazil. A total of 105 patients with scabies (58 children and 57 adults) were included in the study. The diagnosis was made by dermatoscopy, skin scraping, and adhesive film test.

RESULTS

Feelings of shame was the restriction most frequently noted (adults 77.2% and children 46.6%). Other types of quality of life impairment were the need to dress differently (35.1 vs. 29.3%), restriction on leisure activities (24.6 vs. 36.8%), social exclusion (24.6 vs. 17.9%), stigmatization (21.1 vs. 25.0%), teasing (only children: 26.3%), and problems with sexual partners (only adults: 10.9%). Women and girls perceived more restrictions than men and boys. mDLQI scores indicated that 13.9% of the patients noticed a large or very large effect on their life, 65.2% considered their quality of life lightly or moderately reduced by scabies, and 20.9% did not feel any restrictions. The degree of impairment increased parallel to the degree of itching and severity of scabies (P=0.003).

LIMITATIONS

Owing to active case finding, most of the patients were in an early phase of scabies, and clinical pathology was not very pronounced.

CONCLUSION

Scabies considerably impaired the quality of life in adults and children living in poverty in an urban slum. Females particularly suffered from restrictions.