Crusted scabies as a cause of longitudinal nail splitting

Ungual Scabies: A Case Report and Review of Literature

Introduction

Nail unit infestation by scabies mites (ungual scabies) is uncommon. It usually presents with distal subungual lesions, leading to recurrent and persistent disease by acting as a reservoir of infection. Periungual involvement in scabies with nail loss is rare and may lead to severe nail damage.

Case Presentation

We report a 14-year-old boy on chemotherapy for acute lymphocytic leukemia (ALL) who presented with extensive scaling and crusted plaques of scabies. Nail unit revealed periungual crusted plaques with paronychia and onychomadesis involving five digits. It was associated with partial to complete nail loss. Dermoscopy of periungual crusted plaques showed greyish-white scales with brown dots and globules. A sinuous burrow with a brown-triangular structure was visualized in the web space. KOH mount from skin scrapings showed the scabies mites. Treatment of scabies led to a marked improvement.

Conclusion

Though ungual scabies is generally a benign disease, proximal periungual involvement with damage to nail matrix is possible, leading to nail loss. We review manifestations of nail unit scabies reported in literature. Treatment options used and outcomes are also analyzed. The importance of nail-directed therapy in preventing relapses of scabies cannot be undermined.

Sarcoptes Infestation. What Is Already Known, and What Is New about Scabies at the Beginning of the Third Decade of the 21st Century?

Currently, there are three known subtypes of scabies: ordinary, crusted, and bullous. The worldwide prevalence of scabies remains high in the 21st century. To decrease the social, economic, and psychological impact on the enormous population infected, a lot of important work has been completed over the last 20 years concerning the management of scabies. For example, a standardization of guidelines for the treatment of scabies has been completed and programs have been designed for the prevention and treatment in endemic populations, called mass drug administrations. Unfortunately, these only apply to the ordinary form of scabies. Moreover, resistance to the drugs currently used in treatment is growing, which imposes the need to search for new treatments. For this purpose, new acaricides are being developed to enhance the therapeutic options for the patients' benefit and effectively treat this disease. There is also the necessity for prevention before the development of scabies. An effective vaccine has the potential to protect people before this disease, especially in endemic areas. Unfortunately, there are no such vaccines against Sarcoptes yet.

Prevalence of Nail Scabies: A French Prospective Multicenter Study

INTRODUCTION

To assess the prevalence of nail involvement in children <16 years old with a confirmed diagnosis of scabies.

STUDY DESIGN

Observational, prospective study in 7 French dermatology departments between June 2015 and January 2017. Children were included if they had scabies confirmed by dermoscopy and/or microscopy and if nails could be sampled. The first toenails and thumbnails as well as clinically affected nails were systematically sampled for microscopic examination. Individual data were recorded via a standardized questionnaire.

RESULTS

A total of 47 children with scabies were included (26 females [55.3%], mean age 3.6 ± 4.0 years). Pruritus was present in 42 children (89.3%); the relapse rate was 38.3% (n = 18). In 3 infants (6.4%), Sarcoptes mites were revealed by dermoscopy or microscopy of the first toenails (2 cases) and a thumbnail (1 case), but nails were normal in 2 children. Two of the 3 infants had already received treatment for scabies in the previous weeks.

CONCLUSION

Prevalence of nail involvement in children with confirmed scabies was 6.4%. Nails should not be overlooked during scabies treatment.

Nail Scabies: An Unusual Presentation Often Overlooked and Mistreated

Nail scabies is an interesting clinical presentation of scabies. Although it is usually found concomitant with characteristic dermatologic manifestations, it may present as an isolated finding in the immunocompromised host. This condition is commonly mistaken with other diseases such as nail dystrophy, nail psoriasis and onychomycosis. We report two cases of unusual nail presentations that provide clues to diagnosis. Also, literature on unusual nail and dermatologic presentations was reviewed to recognize dermatologist consideration for appropriate treatment options.

[Scabies of the nail unit in an infant]

BACKGROUND

There are no guidelines regarding the management of scabies in infants and recurrence is common at this age. We report the case of an infant with subungual hyperkeratosis and ungual lesions subsequent to classic scabies.

PATIENTS AND METHODS

A 7-month-girl, treated 6 weeks earlier with esdepallethrin for scabies, consulted for acquired lesions on 3 toe nails. These nails were thickened and displayed subungual hyperkeratosis. Physical examination of the skin, the finger nails and mucous membranes was otherwise normal. Fungal analyses were negative, but direct microscopic examination revealed numerous larvae of Sarcoptes scabiei as well as ovular debris. The child was treated with urea 40% to obtain chemical avulsion of the nails, and with topical esdepallethrin and a quarter tablet of ivermectin orally; there was no follow-up of the child.

DISCUSSION

Ungual scabies has already been reported in crusted scabies and very rarely in classic scabies. Subungual and ungual locations of S. scabiei may constitute a source of reinfestation with scabies in infants. Treatment is not well defined and currently involves chemical avulsion of the nails and the application of topical antiscabies treatment.

Scabies

Scabies is an ectoparasite caused by the mite Sarcoptes scabiei var hominis, an obligate human parasite. There are about 300 million cases of scabies in the world each year. Common predisposing factors are overcrowding, immigration, poor hygiene, poor nutritional status, homelessness, dementia, and sexual contact. Direct skin-to-skin contact between 15 and 20 minutes is needed to transfer the mites from one person to another. The diagnosis suspected with a clinical history of itch, worse at night, affecting other family members, clinical distribution, and appearance. Definite diagnosis relies on microscopic identification of the mites, eggs, or fecal pellets with 10% potassium hydroxide, ink enhancement, tetracycline fluorescence tests, or mineral oil; other methods include: epiluminescence light microscopy and S. scabiei DNA. The most commonly used treatment modalities are permethrin and ivermectin. Persistence of symptoms for 2-6 weeks after successful treatment is common. Most recurrences are because of reinfection from untreated contacts.