The detection of Sarcoptes scabiei in human skin by in vivo confocal microscopy

ARTICLE

ejd.2011.1518

Auteur(s) : Enver Turan¹ enverturan@gmail.com, Asli Turgut Erdemir², Mehmet Salih Gurel², Yeliz Karakoca Basaran²

¹ Department of Dermatology, Batman Regional Government Hospital, Gultepe mah 4305, 72070 Batman, Turkey

² Department of Dermatology, Istanbul Education and Research Hospital, Istanbul, Turkey

In vivo reflectance-mode confocal microscopy (RCM) allows for non-invasive, high-resolution imaging of the skin. Tissue processing and staining is not necessary because imaging is based on the detection of backscattered light [1]. We investigated the possibility of detecting Sarcoptes scabiei by using RCM. Two cases with diagnosed scabies were examined with RCM, and diagnostic images were taken.

Two male patients (17 and 38 years old) presented with a widespread, severely itchy papulonodular rash. By clinical criteria and dermoscopic and light microscopic examination, we diagnosed the patients as having scabies. We used RCM to examine a large number of skin lesions on the patients.

According to confocal images, individual S. scabiei appeared as a globular body with very short legs. We observed refractive bristles and spines (denticles) in the dorsal surface. In the anterior segment of the mite, we detected refractive short structures corresponding to the two pairs of legs (figure 1A, yellow arrows). The head was vaguely discernible as a ovoid refractive structure between the anterior legs at the front (white arrow). Refractive spine-like structures were present on the posterior segment of the mite. These structures correspond to the two pairs of short legs and trailing hairs or setae (red arrows). We also observed some smaller and highly refractive structures consistent with mite faeces or scybala (yellow rectangle). Six ovoid mite eggs in the tunnel provided an interesting image (figure 1C).

RCM is a non-invasive imaging method used in the evaluation of benign and malignant skin lesions and has a wide field in basic and clinical dermatology [2]. In these case series, we used the multilaser RCM (VivaScope 1500, Lucid inc, Rochester, NY, USA) system for evaluating the lesional field. Wavelengths of 785 nm (near-infrared), 658 nm (red) or 445 nm (blue) are available with this system. The best quality images were performed with the maximum wavelength (785 nm).In the literature, there are two different case reports, in which patients diagnosed with scabies microbiologically were examined with RCM and ovoid mites were determined in the epidermis. Moreover, linear tunnels within the epidermis and sarcoptic eggs, faeces (scybala) inside these tunnels were also observed [3, 4].

RCM is a real-time digital imaging system with a video display that allows the vitality and movement of the living tissue to be observed. For example, Levi et al were able to detect the movement of S. scabiei by RCM. They reported that the pulsation which could be seen on the mite's body was consistent with physiological gut peristalsis. Also, they emphasized that RCM visualization of peristalsis of the mite's gut appears to be a reliable indicator of the parasite's viability in vivo and might be useful in the clinical situation to determine scabicide efficacy [5].

We detected individual adult mites as well as six embryonated eggs in a tunnel. A thin shell around all embryonated sarcoptic eggs was remarkable. This review of two patients with RCM revealed the embryonic period of S. scabiei. Conventional methods such as tape stripping or the removal of mites with a needle is difficult and may kill or disrupt the integrity of the mites. RCM analysis, however, allows real-time monitoring of living mites without tissue processing or staining. Dermoscopic examination is also a new and useful method for detecting S. scabiei but has a much lower magnification which shows the mites as small triangular structures; therefore, the viability of the mites cannot be seen [6]. RCM has provided a diagnostic image for the diagnosis of S. scabiei. This method could be useful in confirming the diagnosis in patients with symptoms suspicious of scabies.

Disclosure

Financial support: none. Conflicts of interest: none.

References

1. Gonzalez S, Gilaberte-Calzada Y. In vivo reflectance-mode confocal microscopy in clinical dermatology and cosmetology. Int J Cosmet Sci 2008 ; 30 : 1-17.

2. Branzan AL, Landthaler M, Szeimies R.M. In vivo confocal scanning laser microscopy in dermatology. Lasers Med Sci 2007 ; 22 : 73-82.

3. Longo C, Bassoli S, Monari P, Seidenari S, Pellacani G. Reflectance-mode confocal microscopy for the in vivo detection of Sarcoptes scabiei. Arch Dermatol 2005 ; 141 : 1336.

4. Ahlgrimm-Siess V, Koller S, El Shabrawi-Caelen L, Hofmann-Wellenhof R, Kerl H. New diagnostic methods in dermatopathology: in vivo reflectance confocal microscopy. J Dtsch Dermatol Ges 2008 ; 6 : 591-592.

5. Levi A, Mumcuoglu KY, Ingber A, Enk C.D. Assessment of Sarcoptes scabiei viability in vivo by reflectance confocal microscopy. Lasers Med Sci 2011 ; 26 : 291-292.

6. Prins C, Stucki L, French L, Saurat JH, Braun R.P. Dermoscopy for the in vivo detection of sarcoptes scabiei. Dermatology 2004 ; 208 : 241-243.