Optical coherence tomography in diagnosis of inflammatory scalp disorders.

BACKGROUND: The common inflammatory scalp disorders share similar clinical manifestations, and patient work up require invasive, undesirable diagnostic procedures like biopsy to ensure correct diagnosis. Optical coherence tomography (OCT) is a non-invasive high-resolution imaging modality that has found a valuable tool to assist in the diagnose and evaluation of different skin diseases. OBJECTIVES: To describe the structural and vascular dynamic OCT (D-OCT) findings of inflammatory scalp disorders including scalp psoriasis, seborrhoeic dermatitis and contact dermatitis and to compare trichoscopy and OCT features. METHODS: Subjects with diagnosis of seborrhoeic dermatitis, psoriasis or contact dermatitis were enrolled in this study. OCT scans were taken on involved scalp, and the same scalp regions were evaluated by trichoscopy and compared with healthy scalp. RESULTS: A total of fourteen subjects (two healthy controls, four seborrhoeic dermatitis, five psoriasis and three contact dermatitis) participated. D-OCT imaging of vascular pattern in healthy scalp and the inflammatory scalp disorders were described. D-OCT images could enhance the clinician's ability to distinguish psoriasis from seborrhoeic dermatitis by objectively detect and assess red loop density. In scalp contact dermatitis, the vessels of the deep plexus were more dilated and fewer in number than those found in seborrhoeic dermatitis. CONCLUSION: Dynamic OCT provides information that more clearly elucidates changes at the level of the superficial and deep plexuses without invasively interfering with superficial structures. In the context of inflammatory scalp disorders, this is useful to discern disorders with overlapping symptoms and minimize the use of invasive biopsies to diagnose.

Investigation of using very high-frequency ultrasound in the differential diagnosis of early-stage pemphigus vulgaris vs seborrheic dermatitis.

BACKGROUND: Early-stage pemphigus vulgaris (PV) often manifests as erythema alone. We hypothesized that very high-frequency ultrasonography (VHFUS) features could simplify the differential diagnosis of early-stage pemphigus vulgaris versus seborrheic dermatitis (SD). MATERIALS AND METHODS: Fourteen patients with SD or early-stage PV were recruited from our outpatient clinic during 2016-2019. We used 50-MHz VHFUS to image the erythema on the patients' scalp, face, chest, and back and retrospectively evaluated their ultrasonographic features. RESULTS: Very high-frequency ultrasonography images of early-stage PV showed enhanced epidermal echo (8/14, 57%), linear or oval intra-epidermal hypoechoic/anechoic areas (12/14, 86%), linear anechoic areas at the dermal-epidermal junction (14/14, 100%), reduced echo of superficial to whole dermis (9/14, 64%), and slightly increased dermal thickness (14/14, 100%). The intra-epidermal hypoechoic/anechoic bands (100%) showed the greatest specificity. VHFUS images of SD showed enhanced epidermal echo (7/14, 50%), epidermal unevenness (7/14, 50%), linear anechoic bands at the dermal-epidermal junction (8/14, 57%), reduced middle dermis echo (10/14, 71%), and slightly increased dermal thickness (10/14, 71%). The epidermal unevenness (100%) had the greatest specificity. There was a significant difference (P < .05) between early-stage PV and SD regarding the proportion of linear intraepithelial hypoechoic/anechoic bands and linear anechoic areas at the dermal-epidermal junction. CONCLUSIONS: Early-stage PV and SD have relatively specific VHFUS erythematous manifestations. Intra-epidermal hypoechoic/anechoic bands for early-stage PV and epidermal unevenness for SD were most specific. VHFUS contributes to the differential diagnosis of PV and SD by highlighting their features, that is, intra-epidermal hypoechoic/anechoic bands and linear anechoic areas at the dermal-epidermal junction.

A 40-100 MHz B-scan ultrasound backscatter microscope for skin imaging.

There is a growing interest in high resolution, subsurface imaging of cutaneous tissues using higher frequency ultrasound, and several commercial systems have been developed recently which operate at 20 MHz. Some of the possible applications of higher frequency skin imaging include tumour staging, boundary definition, and studies of the response of tumours to therapy, investigations of inflammatory skin conditions such as psoriasis and eczema, and basic studies of skin aging, sun damage and the effects of irritants. Investigation of these areas is quite new, and the role of ultrasound skin imaging is continuing to evolve. Lateral resolution in the 20 MHz imaging systems ranges from 200 to 300 microns, which limits imaging applications to cutaneous structures which are relatively large in size. In this paper, a real-time ultrasound backscatter microscope (UBM) for skin imaging is described which operates in the 40-100 MHz range, providing axial resolution between 17 and 30 microns and lateral resolution between 33 and 94 microns. This improvement in resolution over current skin ultrasound systems should prove useful in determining the margins of small skin lesions, and in obtaining more precise, in vivo skin thickness measurements to characterize nonmalignant skin disease. Example images of normal skin, seborrhoeic keratosis and malignant melanoma illustrate the imaging potential of this system.