Scabies incognito presenting as urticaria pigmentosa in an infant

Scabies in infants and children - a narrative review

Scabies is a human ectoparasitosis caused by Sarcoptes scabei var. hominis. World-wide around 300 million patients are affected. Infants and children have the highest incidence rates. Poverty and overcrowding are social factors contributing to a higher risk of transmission and treatment failure. The leading symptom of the infestation is itch. Complications are bacterial infections that are responsible for mortality. Diagnosis is clinical. Non-invasive imaging technologies like dermoscopy can be used. Polymerase chain reaction (PCR) is less sensitive and specific than microscopy of skin scrapings. Treatment of choice is topical permethrin 5%. Ivermectin is the only oral drug FDA-approved for scabies. It should be used in cases non-responsive to topical therapy and in case of high number of infested patients in addition to topical therapy. Pseudo-resistance to treatment is not uncommon. New drugs are on the horizon. What is Known: • Pruritus is the leading symptom causing sleep disturbances and scratching with the risk of secondary bacterial infections. • Treatment failure is related to inappropriate application of topical drugs and asymptomatic family members. What is New: • COVID-19 pandemic and migration are contributing to an increased incidence of scabies. • New compounds to treat scabies are on the horizon.

Mimics of Dermatitis

Dermatitis is a common condition frequently encountered by dermatologists. The diagnosis of dermatitis can be challenging because this condition is often multifactorial, and many skin diseases that can mimic dermatitis should be considered in the differential diagnosis. It is important to recognize and be familiar with these conditions because some of them can represent signs of systemic disease or malignancies and misdiagnosis can lead to mismanagement and adverse outcomes for the patient.

A Case of Scabies Presenting as Chronic Urticaria

Scabies outbreaks are relatively common worldwide, particularly in communal living settings such as military barracks. The infestation is caused by the parasite Sarcoptes Scabiei and is easily treated once properly diagnosed. Classic symptoms include pruritus around the waist, wrists, and ankles.1 On physical examination, linear burrows visualized in finger web spaces is a typical finding.1 It is not uncommon, however, for scabies to present with a variety of other dermatologic manifestations, which can lead to a delayed or missed diagnosis. This case highlights a delayed diagnosis of scabies, initially presenting as urticaria in a 26-year-old active duty male living in military barracks where multiple previous outbreaks were identified. Providers should be aware of the oftentimes-elusive diagnosis of scabies and the many nonclassic dermatologic manifestations. A thorough skin examination with skin scrapings and examination of the finger web spaces should be considered in those with ambiguous skin rashes who are particularly at risk for scabies infection, such as military recruits, submariners, and other service members living in communal settings. Timely and accurate diagnosis and treatment is crucial to prevent reinfection and spread of scabies throughout these communal living settings.

Update on parasitic dermatoses

These are cutaneous diseases caused by insects, worms, protozoa, or coelenterates which may or may not have a parasitic life. In this review the main ethological agents, clinical aspects, laboratory exams, and treatments of these dermatological diseases will be studied.

Scabies masquerading as bullous pemphigoid: scabies surrepticius

Scabies, a parasitic infestation caused by the mite Sarcoptes scabiei, is diagnosed by observing either the mite, its ova, or its excrement. The mite tracts, known as burrows and a characteristic presentation of the pruritic condition, are typically found on the web spaces between the fingers. Other cutaneous lesions include excoriated papules, pustules, and vesicles. However, atypical clinical variants of scabies, such as bullous, crusted, hidden, incognito, nodular, and scalp forms of the parasitic infestation, mimic the morphologic features of other non-parasitic dermatoses. A 76-year-old man presented with pruritic blisters and urticarial plaques that demonstrated not only pathology changes, but direct immunofluorescence also showed findings of bullous pemphigoid. His condition improved, but did not resolve, with topical corticosteroid cream for the management of the primary autoimmune blistering disorder. When other family members subsequently developed scabies, the correct diagnosis for his condition, bullous scabies, was established by demonstrating mites, ova, and scybala on a mineral oil preparation from a skin scraping of a newly appearing burrow. Bullous scabies can masquerade not only clinically, but also both pathologically and immunologically as bullous pemphigoid. Scabies serrupticius is introduced as a unifying term to designate all of the non-classic presentations of S. scabiei mite infestation.

Clinical phenotype of scabies by age

OBJECTIVE

Scabies has a clinical presentation that seems to vary according to age. We conducted a prospective study with the goal of delineating the clinical presentation of the disease into 3 groups of age: infants, <2 years; children, 2 to 15 years; and adults, >15 years.

METHODS

This trial was a prospective, multicenter observational study in consecutive patients with a confirmed diagnosis of scabies who were seen in 13 French Departments of Dermatology and Pediatric Dermatology between April 2010 and April 2011. A standardized questionnaire was completed for each patient. To identify factors associated with patient age, comparisons between the 3 age groups were conducted by using univariate and multivariate multinomial logistic regression analyses.

RESULTS

A total of 323 individuals were included; the gender ratio (female:male) was 1.2:1. In univariate analysis, infants were more likely to have facial involvement. In multivariate logistic regression, relapse was more frequent in children (odds ratio [OR]: 2.45 [95% confidence interval (CI):1.23-4.88]) and infants (OR: 3.26 [95% CI: 1.38-7.71]). In addition, family members with itch (OR: 2.47 [95% CI: 1.04-5.89]), plantar (OR: 20.57 [95% CI: 7.22-58.60]), and scalp (OR: 16.94 [95% CI: 3.70-77.51]) involvement were also found to be independently associated with the age group <2 years.

CONCLUSIONS

There is a specific clinical presentation of scabies in infants and children. Taking into account these specificities may be helpful for the early diagnosis and the identification of cases to prevent the propagation of the disease.

Crusted (Norwegian) scabies following systemic and topical corticosteroid therapy

It is a case study of a 62-yr-old female with crusted (Norwegian) scabies, which appeared during her treatment with systemic and topical corticosteroid therapy, under the diagnosis of erythroderma. In the same time, the patient had been suffered from hypothyoidism, and her skin changes were misdiagnosed, because it was thought that they are associated with her endocrine disorder. Suddenly, beside the erythema, her skin became hyperkeratotic, with widespread scaling over the trunk and limbs, and crusted lesions appeared on her scalp and ears. The microscopic examination of the skin scales with potassium hydroxide demonstrated numerous scabies mites and eggs. Repeated topical treatments with lindan, benzoyl benzoat and 10% precipitated sulphur ointment led to the complete resolution of her skin condition.

Scabies presenting as solitary mastocytoma-like eruption in an infant

We report a case in which the initial clinical finding was a solitary cutaneous nodule on the wrist of a young infant which urticated when rubbed, and was diagnosed as a solitary mastocytoma. Two months later, she had the onset of a new vesiculo-pustular eruption on the palms and soles, consistent with scabies infestation and treatment with topical permethrin 5% cream resulted in resolution of the entire eruption, including the primary nodule. While scabies has been reported to mimick a variety of conditions including urticaria pigmentosa, to our knowledge no previous cases masquerading as solitary mastocytoma have been reported.

Atypically distributed cutaneous lesions of Norwegian scabies in an HIV-positive man in South India: a case report

INTRODUCTION

Immune-compromised subjects, especially those with underlying HIV disease, are prone to be infected with Norwegian scabies, where the cutaneous lesions are classically distributed over the extremities.

CASE PRESENTATION

We report the case of an HIV-positive 16-year-old man with severe crusted Norwegian scabies initially misdiagnosed as a dermal fungal infection. The patient had extensive, generalized, thick, hyperkeratotic, crusting, yellowish papule lesions distributed on the entire body from his scalp to his toes.The patient was started with Ivermectin and topical Permethrin, which eventually resulted in complete resolution. Interestingly, despite quarantining efforts, one of the patient's acquaintances and a healthcare worker acquired the symptoms of itching.

CONCLUSION

This atypical presentation of Norwegian scabies emphasizes the need to include scabies in the differential diagnosis when HIV-infected patients present with crusted, generalized cutaneous lesions.

Scabies, pediculosis, bedbugs, and stinkbugs: uncommon presentations

Parasitic agents determine some of the most common skin disorders. Although well known, they could present different manifestations or be modified by individual or external factors that make their diagnosis or treatment difficult. This review will discuss some of the most prevalent parasitic infections, scabies, and pediculosis and also mention reactions determined by contact with certain insects that, although rarely found, could induce important skin reactions.

Unusual laboratory findings in a case of Norwegian scabies provided a clue to diagnosis

The diagnosis of Norwegian scabies was missed for a year for an elderly long-term-care facility resident. Serpiginous tracks were noted on the surface of Sabouraud dextrose agar used for fungal culture of the skin scrapings. This unusual laboratory manifestation must alert clinical microbiologists to the possible diagnosis of scabies.