In vivo reflectance confocal microscopy of the skin: A noninvasive means of assessing body cystine accumulation in infantile cystinosis - 21/03/13

Doi : 10.1016/j.jaad.2011.08.010

Christine Chiavérini, MD, PhD ^a,^e,^⁎ , Hee-Young Kang, MD ^a, Laura Sillard, MD ^a, Etienne Berard, MD ^b, Patrick Niaudet, MD ^c, Geneviève Guest, MD ^c, Mathilde Cailliez, MD ^d, Philippe Bahadoran, MD, PhD ^a, Jean Philippe Lacour, MD ^a, Robert Ballotti, PhD ^e, Jean Paul Ortonne, MD ^a
^a Department of Dermatology, Archet 2 Hospital, Nice, France
^b Department of Pediatric Nephrology, Archet 2 Hospital, Nice, France
^c Department of Pediatric Nephrology, Necker Hospital, Paris, France
^d Timone Hospital, Marseille, France
^e INSERM U895 Team 1, Nice, France

^∗Reprint requests: Christine Chiavérini, MD, PhD, Department of Dermatology, Archet 2 Hospital, 151 Route Saint Antoine de Ginestière, 06202 Nice, Cedex 3 France.

Abstract

Background

Patients with infantile nephropathic cystinosis have progressive accumulation of cystine in tissues leading to delayed extrarenal complications. No simple tool is available to evaluate the level of body cystine accumulation.

Objective

We sought to determine the value of in vivo reflectance confocal microscopy of the skin in patients with infantile nephrogenic cystinosis.

Methods

Nine patients and control subjects were recruited for this study. Images were acquired by means of a near-infrared reflectance confocal laser scanning microscope.

Results

Scattered bright particles within the papillary dermis were observed in all patients but not in control subjects. The density of particles ranged from numerous (+++) to very few (+/–) and their distribution was heterogeneous. Electron microscopy confirmed that these particles corresponded to cystine crystal deposits within dermal fibroblasts. The density of cystine crystals within the dermis was greater in older patients, in patients with a high leukocyte cystine concentration, and with delayed cysteamine therapy. There was no correlation between the density of cystine deposits and renal disease or hypopigmentation but high levels of deposition occurred in association with extrarenal manifestations.

Limitations

This is a preliminary study on a small sample of patients. Repeated examination and longer follow-up is necessary.

Conclusion

In vivo reflectance confocal microscopy of the skin appears to be a noninvasive means of assessing body cystine accumulation in infantile cystinosis and could be used as a complementary marker of treatment response in addition to leukocyte cystine measurement.

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Key words : cystine, extrarenal complications, in vivo reflectance confocal microscopy, infantile cystinosis, prognosis, skin