utilizing a UHFUS 40-MHz probe, researchers identifed ventral nail plate deposits, irregular or fused nail plates, and signifcantly thicker nail plates in patients with psoriasis compared to controls, with Doppler-ultrasound noting increased nail blood fow and increased vascular resistance [69]. Finally, a recent study using 20-MHz HFUS to compare two treatment arms reliably demonstrated a reduction in the SLEB of psoriatic skin coinciding with clinical improvement, supporting the use of ultrasonography as a useful objective marker in patients with psoriasis [70]. Hidradenitis suppurativa Hidradenitis suppurativa (HS) is an infammatory disease that afects between 0.05 and 4.1% of the population [71– 73]. Tis disease results in chronic infammation of the hair follicle and presents with painful, erythematous nodules that often rupture, forming draining sinus tracts that eventually scar. Current HS staging tools include Hurley staging, HS severity index, HS physician global assessment and sonographic scoring of HS [74, 75]. Hurley staging is generally the most commonly used method for assessment of HS severity, but lacks the ability to efectively measure disease fuctuation and response to treatment [74]. A number of studies have demonstrated that these various staging tools underestimate the true disease severity in comparison to ultrasound-assisted staging of HS [76– 79]. Ultrasound has allowed for understanding of a proposed sequence of skin changes in HS pathology with the earliest sign of follicular widening eventuating in the formation of fstulous tracts and increased vascularity over acutely infamed lesions [78]. A meaningful association between the ultrasonographically measured diameter of an HS nodule and the patient’s subjective assessment of the nodule’s tenderness and the clinician’s assessment of erythema have also been established [80]. Finally, ultrasound can aid in medical and surgical management of HS. One study noted a modifcation in the management of 82% of cases following ultrasonographic evaluation with a 24% transition from medical to surgical management [78]. Atopic dermatitis Atopic dermatitis (AD) is a chronic infammatory skin condition characterized by intense pruritis and abnormal skin barrier function [81]. Currently, there is a lack of standardization of core outcome measurement tools for this disease. Te Harmonising Outcome Measures in Eczema initiative recommends the use of the Eczema Area and Severity Index and the Scoring Atopic Dermatitis in assessing physician-reported signs of AD, noting the utility of the latter in clinical trials [82, 83]. But these disease severity tools are subjective, cumbersome and have demonstrated poor reproducibility [84, 85]. A number of studies have attempted to better understand the severity of AD through the use of ultrasound. In particular, these studies have sought to measure the thickness of the SLEB and skin echogenicity in order to quantify disease burden. Unlike in sun damaged skin, in AD, the SLEB appears to be the result of edema and infammatory cell infltrate in sites of active infammation [13]. In one 2019 study, the mean thickness of the hypoechoic band was found to be higher in lesional skin but present in both lesional and non-lesional skin of individuals with AD [81]. A separate study compared SLEB thickness in patients with AD as visualized by 20-MHz ultrasound to their EASI score and histopathological fndings from 5 mm punch biopsies. Te study found SLEB thickness correlated with the histologic degree of epidermal hyperkeratosis, parakeratosis, spongiosis, and intensity of infammatory infltrates as well as the provider-assessed EASI scores [84]. Finally, two studies using HFUS and UHFUS to examine the efect of phototherapy and tacrolimus on SLEB thickness found statistically signifcant reductions in mean SLEB thickness [86, 87]. Granulomatous diseases Sarcoidosis is characterized by the formation of granulomas in a number of diferent organs and is associated with cutaneous induration and erythema. A pilot study in 2017 evaluated the utility of UHFUS in objectively quantifying granuloma burden in cutaneous sarcoidosis in comparison to the Cutaneous Sarcoidosis Activity and Morphology Instrument (CSAMI) and histopathological evaluation