Laser fluorescence spectroscopy in predicting the formation of a keloid scar: preliminary results and the role of lipopigments

Abstract

Keloid scars, in contrast to other scar types, significantly reduce the patient's quality of life. To develop a nondestructive optical diagnostic technique predicting the keloid scars formation in vivo, laser-induced fluorescence spectroscopy (LFS) was used to study the autofluorescence in skin of patients with various types of head and neck cicatricial deformities. The unexpected results were obtained for the endogenous fluorescence of lipofuscin. Significantly reduced autofluorescence of lipofuscin was registered both in the intact and in the keloid scar tissues in comparison with the intact and scar tissues in patients with hypertrophic and normotrophic scars. Sensitivity and specificity achieved by LFS in keloid diagnosis are 81.8% and 93.9% respectively. It could take place due to the changes in the reductive-oxidative balance in cells, as well as due to the proteolysis processes violation. Therefore, we suppose that the evaluation of the lipofuscin autofluorescence in skin before any surgical intervention could predict the probability of the subsequent keloid scars formation.

Fig. 1.

a) Keloid scar on a woman aged 66 years, four years after surgery. Corticosteroids ongoing at the time of autofluorescence recording. b) Fiber probe tip is placed in a gentle contact with the keloid scar for autofluorescence spectra recording. Fluorescence excitation wavelength λ_e=635 nm.

Fig. 2.

The histological assessment of different cicatricial deformity types. Hematoxylin and eosin staining. A - normal skin: actinic elastosis manifestations in the upper dermis, pilosebase complexes; B - normotrophic scar: collagen fibers are oriented parallel to the skin surface. Vertically oriented vessels. Adnexal structures are absent; C - hypertrophic scar: nodular structures with the multidirectional collagen fibers, fibroblast proliferation; D - keloid scar: Wide hyalinized collagen ribbons.

Fig. 3.

An example of the healthy skin fluorescence spectra in patients with normotrophic (patient’s age is 52 years, green curve), hypertrophic (61 years of age, red curve), keloid scar (28 years of age, grey curve) for excitation wavelength (λ_e) 535 nm.

Fig. 4.

The indices of the tissue lipofuscin healthy skin content η (585)₅₃₅ expressed in arbitrary units (M ± SD) in different age groups. n – number of patients in each group; N – number of areas under investigation in each group.