Impact of COVID-19 pandemic on acute dermatology referrals in a secondary and tertiary care Central London hospital. A retrospective comparison review of pre-COVID-19 era and COVID-19 pandemic.

BACKGROUND: Although Dermatology is largely considered an outpatient specialty, there is an increasing need for Dermatology input in the acute and inpatient setting. During the COVID-19 pandemic, Dermatology services had to be reorganized to facilitate staff redeployment and minimize the risk of exposure to COVID-19 for patients and staff. This led to an unprecedented increase in teleconsultations aided by clinical images. OBJECTIVES: The main aim of our retrospective study was to analyse the acute Dermatology referrals received in the pre-COVID-19 era and during COVID-19 pandemic. METHODS: We retrospectively analysed acute Dermatology referrals using the acute referral log. RESULTS: We retrospectively analysed 500 and 110 acute Dermatology referrals received in the pre-COVID-19 period and during COVID-19 pandemic, respectively. In the pre-COVID-19 era, consultations were most commonly requested by Oncology/Haemato-Oncology, Emergency Departments and General Practice, while during the COVID-19 pandemic General Practice was the most common source of referrals. A wide variety of dermatological conditions were encountered with the most common been eczematous dermatoses. CONCLUSIONS: Although Dermatology is largely an outpatient-based specialty, this study shows the demand for urgent Dermatology input the care of sick patients with severe skin diseases and in the management of skin problems in patients admitted or receiving treatment for other diseases. Re-organization of Dermatology services during the COVID-19 pandemic resulted in a marked increase in teleconsultations (28% versus 84.5%) and highlighted the importance of complete skin-directed physical examination by the referring clinician as well as procurement of good quality clinical images.

Leg ulceration due to cutaneous melioidosis in a returning traveller.

A 26-year-old man, returned to the UK having travelled extensively in Asia. He was referred with a 3-month history of distal leg ulceration following an insect bite while in Thailand. Despite multiple courses of oral antibiotics, he developed two adjacent ulcers. A wound swab isolated an organism identified as Burkholderia thailandensis The histology of the skin biopsy was non-specific. A diagnosis of cutaneous melioidosis was made, based on clinical and microbiological grounds. The ulcers re-epithelialised on completion of intravenous ceftazidime followed by 3 months of high dose co-trimoxazole and wound care. Many clinical microbiology laboratories have limited diagnostics for security-related organisms, with the result that B. pseudomallei, the causative bacterium of melioidosis, may be misidentified. This case highlights the importance of maintaining high levels of clinical suspicion and close microbiological liaison in individuals returning from South-East Asia and northern Australia with such symptoms.

PPE-associated dermatoses: effect on work and wellbeing.

The COVID-19 pandemic has led to more stringent infection control practice within hospitals, with the added requirement of personal protective equipment (PPE). Consequentially, the incidence of PPE-related dermatoses in healthcare workers is increasing. Analysis of staff members seen in a dermatology self-referral service during the first COVID-19 peak revealed a wide range of healthcare professionals being affected, with irritant hand dermatitis and acneiform eruptions being the commonest diagnoses. These PPE-related dermatoses had significant effects on staff members' work and wellbeing, which improved following assessment and treatment by dermatology. Given the change to our behaviour wearing PPE daily, which is likely to continue for the foreseeable future, the consequences will inevitably affect both healthcare workers and the general public, with these common dermatoses presenting in both primary and secondary care. It is therefore imperative to recognise both the physical and emotional impact that COVID-19 PPE has, and initiate prompt treatment to improve wellbeing.

Induction of hair follicle dermal papilla cell properties in human induced pluripotent stem cell-derived multipotent LNGFR(+)THY-1(+) mesenchymal cells.

The dermal papilla (DP) is a specialised mesenchymal component of the hair follicle (HF) that plays key roles in HF morphogenesis and regeneration. Current technical difficulties in preparing trichogenic human DP cells could be overcome by the use of highly proliferative and plastic human induced pluripotent stem cells (hiPSCs). In this study, hiPSCs were differentiated into induced mesenchymal cells (iMCs) with a bone marrow stromal cell phenotype. A highly proliferative and plastic LNGFR(+)THY-1(+) subset of iMCs was subsequently programmed using retinoic acid and DP cell activating culture medium to acquire DP properties. The resultant cells (induced DP-substituting cells [iDPSCs]) exhibited up-regulated DP markers, interacted with human keratinocytes to up-regulate HF related genes, and when co-grafted with human keratinocytes in vivo gave rise to fibre structures with a hair cuticle-like coat resembling the hair shaft, as confirmed by scanning electron microscope analysis. Furthermore, iDPSCs responded to the clinically used hair growth reagent, minoxidil sulfate, to up-regulate DP genes, further supporting that they were capable of, at least in part, reproducing DP properties. Thus, LNGFR(+)THY-1(+) iMCs may provide material for HF bioengineering and drug screening for hair diseases.

'Hints' in the horn: diagnostic clues in the stratum corneum.

The stratum corneum or horny layer is the uppermost layer of the epidermis, and is mainly responsible for the skin's barrier function. In spite of its complexity at the ultrastructural and molecular level, the features accessible to visualization on conventional histology are relatively limited. Nevertheless, knowledge of subtle clues that one may observe in the stratum corneum can prove useful in a wide range of situations in dermatopathology. We herein review a selection of common and rare entities in which the horny layer may reveal significantly important hints for the diagnosis. These clues include parakeratosis and its different patterns (focal, confluent, alternating, associated with spongiosis, epidermal hyperplasia or lichenoid changes), subcorneal acantholysis, infectious organisms in the stratum corneum (including fungal, bacterial and parasitic), thickening or thinning of the stratum corneum and the presence of different kinds of pigment. Even when normal, the horny layer may prove to be useful when seen in association with severe epidermal damage, a combination of features testifying to the acute nature of the underlying pathological process.

Hair Follicle Miniaturization in a Woolly Hair Nevus: A Novel "Root" Perspective for a Mosaic Hair Disorder.

Woolly hair nevus is a mosaic disorder characterized by unruly, tightly curled hair in a circumscribed area of the scalp. This condition may be associated with epidermal nevi. We describe an 11-year-old boy who initially presented with multiple patches of woolly hair and with epidermal nevi on his left cheek and back. He had no nail, teeth, eye, or cardiac abnormalities. Analysis of plucked hairs from patches of woolly hair showed twisting of the hair shaft and an abnormal hair cuticle. Histopathology of a woolly hair patch showed diffuse hair follicle miniaturization with increased vellus hairs.

Strategies to enhance epithelial-mesenchymal interactions for human hair follicle bioengineering.

Hair follicle morphogenesis and regeneration depend on intensive but well-orchestrated interactions between epithelial and mesenchymal components. Accordingly, the enhancement of this crosstalk represents a promising approach to achieve successful bioengineering of human hair follicles. The present article summarizes the techniques, both currently available and potentially feasible, to promote epithelial-mesenchymal interactions (EMIs) necessary for human hair follicle regeneration. The strategies include the preparation of epithelial components with high receptivity to trichogenic dermal signals and/or mesenchymal cell populations with potent hair inductive capacity. In this regard, bulge epithelial stem cells, keratinocytes predisposed to hair follicle fate or keratinocyte precursor cells with plasticity may provide favorable epithelial cell populations. Dermal papilla cells sustaining intrinsic hair inductive capacity, putative dermal papilla precursor cells in the dermal sheath/neonatal dermis or trichogenic dermal cells derived from undifferentiated stem/progenitor cells are promising candidates as hair inductive dermal cells. The most established protocol for in vivo hair follicle reconstitution is co-grafting of epithelial and mesenchymal components into immunodeficient mice. In theory, combination of individually optimized cellular components of respective lineages should elicit most intensive EMIs to form hair follicles. Still, EMIs can be further ameliorated by the modulation of non-cell autonomous conditions, including cell compartmentalization to replicate the positional relationship in vivo and humanization of host environment by preparing human stromal bed. These approaches may not always synergistically intensify EMIs, however, step-by-step investigation probing optimal combinations should maximally enhance EMIs to achieve successful human hair follicle bioengineering.

Human induced pluripotent stem cell-derived ectodermal precursor cells contribute to hair follicle morphogenesis in vivo.

Well-orchestrated epithelial-mesenchymal interactions are crucial for hair follicle (HF) morphogenesis. In this study, ectodermal precursor cells (EPCs) with the capacity to cross talk with hair-inductive dermal cells were generated from human induced pluripotent stem cells (hiPSCs) and assessed for HF-forming ability in vivo. EPCs derived from three hiPSC lines generated with 4 or 3 factors (POU5F1, SOX2, KLF4 +/- MYC) mostly expressed keratin 18, a marker of epithelial progenitors. When cocultured with human dermal papilla (DP) cells, a 4 factor 201B7 hiPSC-EPC line upregulated follicular keratinocyte (KC) markers more significantly than normal human adult KCs (NHKCs) and other hiPSC-EPC lines. DP cells preferentially increased DP biomarker expression in response to this line. Interestingly, 201B7 hiPSCs were shown to be ectodermal/epithelial prone, and the derived EPCs were putatively in a wingless-type MMTV integration site family (WNT)-activated state. Importantly, co-transplantation of 201B7 hiPSC-EPCs, but not NHKCs, with trichogenic mice dermal cells into immunodeficient mice resulted in HF formation. Human HF stem cell markers were detected in reconstituted HFs; however, a low frequency of human-derived cells implied that hiPSC-EPCs contributed to HF morphogenesis via direct repopulation and non-cell autonomous activities. The current study suggests a, to our knowledge, previously unrecognized advantage of using hiPSCs to enhance epithelial-mesenchymal interactions in HF bioengineering.

Cytokine changes during rituximab therapy in HIV-associated multicentric Castleman disease.

Recent data highlight the importance of inflammatory markers during human immunodeficiency virus type 1 (HIV) infection. HIV-associated multicentric Castleman disease (HIV-MCD) presents with systemic symptoms attributed to cytokine disarray, and we have previously shown that the use of the anti-CD20 monoclonal antibody rituximab induces clinical remissions. Before and during successful rituximab therapy, 15 plasma cytokines were measured as were adaptive (CD4, CD8, CD19) and innate (CD16/56) immune cell populations and HIV-1 viral loads. A significant reduction from baseline of the CD19 B-cell count, consistent with rituximab's mechanism of action, was observed. Markedly elevated cytokine levels were observed before rituximab therapy, and a reduction from baseline values with rituximab therapy was observed for interleukin (IL)-5, IL-6, and IL-10. Therapies that reduce the inflammatory cytokine response are likely to be successful in a range of diseases, including HIV-MCD, and in the future may be used to guide therapeutic strategies.