Infectious skin diseases (Entomodermoscopy)
This chapter describes the dermoscopy aspect of infectious skin diseases
It has the following subchapters:
- Parasitosis
- Scabies
- Cutaneous larva migrans
- Tungiasis
- Pediculosis
- Tick bites
- Demodicidosis
- Viral infections
- HPV infections
- Molluscum contagiusum
Specific dermoscopic patterns have been described for several infectious skin diseases, including those of viral, fungal and parasitic origin.[1]
Of note, use of the new-generations dermatoscopes that do not require direct contact to the skin minimizes the risk of transfection. Interestingly, while the risk of bacterial contamination with dermoscopic examination is reported to be low, viral transmission might still represent a possible problem.[2]
Parasitoses
Scabies
The typical dermoscopic pattern of scabies consists of small dark brown triangular structures located at the end of whitish structureless lines (curved or wavy), giving an appearance reminiscent of a delta-wing jet with contrail (Fig 9a).[3] Microscopically, the brown triangle corresponds to the pigmented anterior part of the mite, while the burrow of the mite correlates dermoscopically to the contrail feature. Since then, the value of dermoscopy in diagnosis of scabies has been extensively investigated in several studies.[4][5][6][7] The diagnostic accuracy of the technique was reported to be at least equal to traditional ex-vivo microscopic examination (i.e. skin scraping), while additional comparative advantages of dermoscopy include its non-invasiveness and lower requirements in terms of time, costs and experience.[6][7] Nowadays, dermoscopy has replaced ex-vivo microscopy as the routine method for diagnosis of scabies in several dermatology centers. Additional to its value for diagnosis, dermoscopy may also be useful in treatment monitoring, heralding treatment success when dermoscopic ‘jet with contrail’ features can no longer been detected.[8]
Tungiasis
Tungiasis is a skin infestation caused by the sand flea Tunga penetrans and is mainly endemic in the tropical regions of South and Central America, Africa, Asia and the Caribbean Islands. Because of its low incidence outside endemic areas, its clinical features are less recognized and diagnosis may be delayed. Dermoscopy of the disease typically reveals a white to flesh colored to light brown nodule with a central targetoid brownish ring, which in turn surrounds a central (often blackish) pore.[9][10]
Cutaneous larva migrans
Dermoscopy has been shown to facilitate the clinical recognition of larva migrans (creeping eruption), by revealing translucent brownish structureless areas in a segmental arrangement, corresponding to the body of the larva.[11]
Pediculosis
Dermoscopy allows a rapid and reliable diagnosis of pediculosis by revealing the lice itself or the nits fixed to the hair shaft (Fig 9b).[12][13]Nits containing vital nymphs dermoscopically display ovoid brown structures, while the empty nits are translucent and typically show a plane and fissured free ending. This information is particularly useful for treatment monitoring, since dermoscopic detection of vital nits should lead to a continuation or modification of therapy. Additionally, dermoscopy has been recently shown to enable the discrimination between nits and the so-called pseudo-nits, such as hair casts, debris of hair spray or gel. The latter are not firmly attached to the hair shaft and appear dermoscopically as amorphous, whitish structures.[14]
Tick bites
Dermoscopy has been reported to highlight the presence of tick infestation by enabling the visualization of their anterior legs protruding from the surface of the skin, while a brown to grey translucent ‘shield’ with pigmented streaks corresponds to the tick’s body (Fig 9d). Following the removal of the tick, detection of brown to black to grey areas of pigmentation by dermoscopy indicates incomplete removal.[15][16]
Demodicidosis
Authors: Horacio Cabo, Emilia Cohen Sabban, Rosario Peralta.
Human demodicosis (DD) is a skin disease of the pilosebaceous units associated with human Demodex, a widely known ectoparasitic mite, involving mainly the face and head. Under dermoscopy, we observed gelatinous threads or filaments protruding out of the follicular openings known as “Demodex tails” and Demodex follicular openings that are dilated follicular openings containing round, amorphic, and yellow/light brown plugs surrounded by an erythematous halo. They are both specific features of DD. Demodicosis can be associated with rosacea and polygonal vessels to be present. The most important differential diagnoses are papulopustular or erythematotelangiectatic rosacea and seborrheic dermatitis. [17] [18]
Demodex tails
Demodex follicular openings
Viral Infections
HPV infections
Common warts (verruca vulgaris) dermoscopically display multiple densely packed papillae, each containing a central red dot or loop, which is surrounded by a whitish halo. Hemorrhages represent a possible additional feature, appearing as irregularly distributed, small, red to black tiny dots or streaks.[1][19][20] Dermoscopy of plantar warts typically reveals multiple prominent hemorrhages within a well-defined, yellowish papilliform surface, in which skin lines are interrupted. This pattern is particularly useful for their discrimination from callus, which lacks blood spots, but instead displays central reddish to bluish structureless pigmentation.[21][22][23] Dermoscopy of plane warts typically reveals regularly distributed, tiny, red dots on a light brown to yellow background. These findings allow differentiation from acne or folliculitis, which display a central white to yellow pore corresponding to the comedo or pus within the hair follicle opening.[1]
The dermoscopic pattern of genital warts was initially described as a mosaic pattern consisting of a white reticular network surrounding central small islands of unaffected mucosal skin.[1] More recently, the authors of a study including a large number of patients identified 4 different dermoscopic patterns, which may also coexist in a single wart: unspecific, fingerlike, mosaic and knoblike pattern.[24] Concerning vessels morphology, glomerular, hairpin/dotted, and glomerular/dotted vessels were detected.
Molluscum contagiosum
Molluscum contagiosum is due to a poxvirus infection and has a characteristic dermoscopic pattern that may facilitate its clinical recognition in selected cases. Dermoscopy is especially useful in detecting the infection before the development of numerous lesions, in pediatric dermatology, or in immunosuppressed patients who may display unusual clinical manifestations. A central pore or umbilication in conjunction with polylobular white to yellow amorphous structures, surrounded by linear or branched vessels (‘red corona’), compose the stereotypic dermoscopic pattern of the disease (Fig 9c).[25][26][27]
- ↑ 1.0 1.1 1.2 1.3 Zalaudek et al.: Entodermoscopy: a new tool for diagnosing skin infections and infestations. Dermatology (Basel) 2008;216:14-23. PMID: 18032894. DOI.
- ↑ Penso-Assathiany et al.: Presence and persistence of human papillomavirus types 1, 2, 3, 4, 27, and 57 on dermoscope before and after examination of plantar warts and after cleaning. J. Am. Acad. Dermatol. 2013;68:185-6. PMID: 23244381. DOI.
- ↑ Argenziano et al.: Epiluminescence microscopy. A new approach to in vivo detection of Sarcoptes scabiei. Arch Dermatol 1997;133:751-3. PMID: 9197830.
- ↑ Bauer et al.: Nodular scabies detected by computed dermatoscopy. Dermatology (Basel) 2001;203:190-1. PMID: 11586026.
- ↑ Prins et al.: Dermoscopy for the in vivo detection of sarcoptes scabiei. Dermatology (Basel) 2004;208:241-3. PMID: 15118379. DOI.
- ↑ 6.0 6.1 Walter et al.: Comparison of dermoscopy, skin scraping, and the adhesive tape test for the diagnosis of scabies in a resource-poor setting. Arch Dermatol 2011;147:468-73. PMID: 21482897. DOI.
- ↑ 7.0 7.1 Park et al.: The diagnostic accuracy of dermoscopy for scabies. Ann Dermatol 2012;24:194-9. PMID: 22577271. DOI.
- ↑ Hamm et al.: Treatment of scabies with 5% permethrin cream: results of a German multicenter study. J Dtsch Dermatol Ges 2006;4:407-13. PMID: 16686608. DOI.
- ↑ Bauer et al.: Dermoscopy of tungiasis. Arch Dermatol 2004;140:761-3. PMID: 15210479. DOI.
- ↑ Bauer et al.: Variability of dermoscopic features of tungiasis. Arch Dermatol 2005;141:643-4. PMID: 15897397. DOI.
- ↑ Veraldi et al.: Epiluminescence microscopy in cutaneous larva migrans. Acta Derm. Venereol. 2000;80:233. PMID: 10954233.
- ↑ Micali et al.: Dermatoscopy: alternative uses in daily clinical practice. J. Am. Acad. Dermatol. 2011;64:1135-46. PMID: 21292346. DOI.
- ↑ Di Stefani et al.: Dermoscopy for diagnosis and treatment monitoring of pediculosis capitis. J. Am. Acad. Dermatol. 2006;54:909-11. PMID: 16635683. DOI.
- ↑ Zalaudek & Argenziano: Images in clinical medicine. Dermoscopy of nits and pseudonits. N. Engl. J. Med. 2012;367:1741. PMID: 23113485. DOI.
- ↑ Oiso et al.: Diagnostic effectiveness of dermoscopy for tick bite. J Eur Acad Dermatol Venereol 2010;24:231-2. PMID: 19686261. DOI.
- ↑ Matsuda et al.: Dermoscopy for tick bite: reconfirmation of the usefulness for the initial diagnosis. Case Rep Dermatol 2011;3:94-7. PMID: 21577370. DOI.
- ↑ Friedman et al.: Usefulness of dermoscopy in the diagnosis and monitoring treatment of demodicidosis. Dermatol Pract Concept 2017;7:35-38. PMID: 28243492. DOI.
- ↑ Segal et al.: Dermoscopy as a diagnostic tool in demodicidosis. Int. J. Dermatol. 2010;49:1018-23. PMID: 20931672.
- ↑ Tanioka et al.: Pigmented wart due to human papilloma virus type 60 showing parallel ridge pattern in dermoscopy. Eur J Dermatol 2009;19:643-4. PMID: 19709979. DOI.
- ↑ Yoong et al.: Unusual clinical and dermoscopic presentation of a wart. Australas. J. Dermatol. 2009;50:228-9. PMID: 19659993. DOI.
- ↑ Lee et al.: The use of dermoscopy for the diagnosis of plantar wart. J Eur Acad Dermatol Venereol 2009;23:726-7. PMID: 19309426. DOI.
- ↑ Dalmau et al.: Acral melanoma simulating warts: dermoscopic clues to prevent missing a melanoma. Dermatol Surg 2006;32:1072-8. PMID: 16918571. DOI.
- ↑ Bae et al.: Differential diagnosis of plantar wart from corn, callus and healed wart with the aid of dermoscopy. Br. J. Dermatol. 2009;160:220-2. PMID: 19067694. DOI.
- ↑ Dong et al.: Dermatoscopy of genital warts. J. Am. Acad. Dermatol. 2011;64:859-64. PMID: 21429619. DOI.
- ↑ Morales et al.: Dermoscopy of molluscum contagiosum. Arch Dermatol 2005;141:1644. PMID: 16365277. DOI.
- ↑ Zaballos et al.: Dermoscopy of molluscum contagiosum: a useful tool for clinical diagnosis in adulthood. J Eur Acad Dermatol Venereol 2006;20:482-3. PMID: 16643165. DOI.
- ↑ Ianhez et al.: Dermoscopic patterns of molluscum contagiosum: a study of 211 lesions confirmed by histopathology. An Bras Dermatol 2011;86:74-9. PMID: 21437525.
