Faculty Bibliography

WHO has declared human mpox (formerly known as monkeypox) a global public health emergency since July, 2022. When case numbers were increasing, so did clinicians' exposures to new elements of the disease. Additionally, the burden of mpox is particularly apparent in immunocompromised patients, who can have more variable and severe manifestations of disease across organ systems. In this Grand Round, we report novel and severe oculocutaneous manifestations of mpox in this population, which are both sight and life threatening. Specifically, we highlight two patients with mpox and AIDS who had refractory skin necrosis that progressed to either ocular compromise or panfacial gangrene, or both. Both patients ultimately died due to systemic complications of their infections. Through clinical analogies, we show how past experiences with related orthopoxviruses, such as variola virus (smallpox) and vaccinia virus, can add useful context for understanding and treating these new disease states. We suspect that in patients who are immunocompromised, monkeypox virus can clinically evolve not only via viraemia but also through direct intradermal spread. We propose that intradermal spread occurs by a process clinically and immunologically analogous to progressive vaccinia, a complication previously seen after conventional smallpox vaccination. We share evidence in support of this theory and implications regarding early management and post-exposure prophylaxis for at-risk populations. Content note: this Grand Round contains graphic images of mpox lesions of the eyes and face.

Linear lichen planus pigmentosus (LPP) of the face is a rare variant of lichen planus, with only a few cases published in the literature.1 It is an inflammatory condition with unknown etiology, characterized by blue-gray hyperpigmented macules, and tends to affect sun-exposed areas of the head and neck.1-4 The pathophysiology of linear lichen pigmentosus is poorly understood, though it is postulated to be caused by T-lymphocyte autoimmunity against keratinocytes.5-7 LPP more frequently affects middle age woman and skin phototypes III-VI.1,3 Treatment for linear LPP is difficult and there is no established first-line therapy; however, tacrolimus ointment, topical corticosteroids, and various systemic agents have shown to be effective in improving the appearance.3,8,9 Prior reports have characterized linear LPP that follows the lines of Blashko as more commonly affecting the trunk.1 We present three cases of linear lichen planus pigmentosus (LPP) of the forehead, a unique novel presentation of linear LPP of the face. One of our cases also provides supporting evidence for tacrolimus to be used as a preferred therapy to treat linear LPP of the face; however, more research is needed to support this claim. To our knowledge, this case series is the largest case series of linear lichen planus pigmentosus (LPP) of the forehead to be reported. J Drugs Dermatol. 2023;22(1):94-97. doi:10.36849/JDD.7200.

Background/Purpose: The skin is recognized as a window into the immunopathogenic mechanisms driving the vast phenotypic spectrum of psoriatic disease.
Method(s): To better decipher the cellular landscape of both healthy and psoriatic skin, we employed spatial transcriptomics (ST), a ground-breaking technology that precisely maps gene expression from histologically-intact tissue sections (Fig. 1A).
Result(s): Findings gleaned from computationally integrating our 23 matched lesional and non-lesional psoriatic and 7 healthy control samples with publicly-available single-cell ribonucleic acid (RNA) sequencing datasets established the ability of ST to recapitulate the tissue architecture of both healthy and inflamed skin (Fig. 1B) and highlighted topographic shifts in the immune cell milieu, from a predominantly perifollicular distribution in steady-state skin to the papillary and upper reticular dermis in psoriatic lesional skin. We also incidentally discovered that ST's ability to ascertain gene expression patterns from intact tissue rendered it particularly conducive to studying the transcriptome of lipid-laden cells such as dermal adipose tissue and sebaceous glands (Fig. 1C), whose expression profiles are typically lost in the process of tissue handling and dissociation for bulk and single-cell RNA seq. Unbiased clustering of pooled healthy and psoriatic samples identified two epidermal clusters and one dermal cluster that were differentially expanded in psoriatic lesional skin (p values <=0.05) (Fig. 1D); pathway analysis of these clusters revealed enrichment of known psoriatic inflammatory pathways (Fig. 1E). Unsupervised classification of skin-limited psoriasis and psoriatic arthritis samples revealed stratification by cutaneous disease severity or Psoriasis Area and Severity Index (PASI) score and not by presence or absence of concomitant systemic/synovial disease (Fig. 1F). Remarkably, this PASI-dependent segregation was also evident in distal, non-lesional samples and was driven by the dermal macrophage and fibroblast cluster and the lymphatic endothelium (Fig. 2A). Inquiry into the mechanistic drivers of this observed stratification yielded enrichment of pathways associated with key T cell and innate immune cell activation, B cells, and metabolic dysfunction (Fig. 2B). Finally, tissue scale computational cartography of gene expression revealed differences in regional enrichment of specific cell types across phenotypic groups, most notably upward extension of fibroblasts to the upper dermis in both lesional and non-lesional samples from mild psoriasis and restriction to the lower dermis in the moderate-to-severe psoriasis samples (Fig. 2C), suggesting that disease severity stratification may be driven by emergent cellular ecosystems in the upper dermis. Fig. 1. (A) Schematic of spatial transcriptomics study workflow. Four mm skin punch biopsies were obtained from healthy volunteers (n=3) and lesional and non-lesional skin from patients with psoriatic disease (n=11). Ten micron-thick sections were then placed on capture areas on the ST microarray slide, each containing molecularly barcoded, spatially encoded spots with a diameter of 50 microns and a center-to-center distance of 100 microns. (B) Side-by-side comparison of a hematoxylin-eosin (H&E) stained section of representative healthy, lesional, and non-lesional skin samples and the corresponding ST plots showed concordance of unbiased gene expression-based clustering with histologic tissue architecture. (C) Pathway analysis of the adipose cluster in healthy skin (cluster 2) confirmed upregulation of lipid-associated processes. Inset: Spots corresponding to the adipose cluster highlighted in yellow. (D) Wilcoxon rank sum test (results displayed as box plots) yielded statistically significant expansion of three clusters in lesional skin compared to both non-lesional and healthy skin-inflamed suprabasal epidermis (cluster 4), epidermis 2 (cluster 7), and inflamed dermis (cluster 10). HC=healthy control, L=lesional psoriatic skin, NL=non-lesional psoriatic skin. (E) Pathways enriched in clusters 4, 7, and 10. (F) Principal component analysis (PCA) plots demonstrating segregation of samples by severity of cutaneous disease in both lesional and non-lesional samples along the first principal component (right) that was not seen in the samples categorized according to presence or absence of arthritis (left). PsA=psoriatic arthritis, PsO=skin-limited psoriasis. Fig. 2. (A) PCA of lesional and non-lesional samples colored by disease severity in spatial clusters 1 (left) and 12 (right) revealed more discrete clustering. (B) Pathways significantly enriched in clusters 1 (left) and 12 (right) showed enrichment of pathways associated with key T cell and innate immune cell activation, B cells, and metabolic dysfunction (highlighted in red). (C) SpaceFold one dimension projection of cell distribution from an independently-generated single-cell RNA seq data set on aggregated ST lesional and non-lesional samples from mild (PASI-low) and moderate-severe (PASI-high) samples. Y-axis represents tissue position, starting with the lower dermis marked as position 0 to suprabasal epidermis marked as position 1. Dashed line represents epidermal-dermal junction, discerned by cell types in the basal epidermal layer (melanocytes and Langerhans cells). Fibroblast signatures (red arrows) were largely relegated to the lower dermis in the PASI-high group, but extended to the upper dermis in the PASI-low group. This striking difference in fibroblast localization was also noted in non-lesional PASI-high vs. PASI-low groups. In addition to fibroblasts, lymphatic, endothelial, myeloid, and T cells signatures (black arrows) were also observed in the upper dermis of lesional PASI-low samples, but were much lower in the dermis of PASI-low non-lesional and all samples in the PASI-high group. Interfollicular epidermis (IFE), hair follicle and infundibulum (HF/IFN), n= number of individual biopsies.
Conclusion(s): Thus, we have been able to successfully leverage ST integrated with independently-generated single-cell RNA seq data to spatially define the emergent cellular ecosystems of healthy and matched psoriatic lesional and non-lesional skin and in so doing, demonstrated the value of ST in unearthing the genetic groundwork at both the site of inflammation and in distal, clinically-uninvolved skin

Pleomorphic dermal sarcoma (PDS) was recognized in the 2013 World Health Organization Classification of Tumors of Soft Tissue and Bone as a clinical entity with adverse histopathologic features compared to the more superficial and less aggressive atypical fibroxanthoma (AFX). Although the gold standard treatment of AFX is Mohs micrographic surgery (MMS), the optimal treatment for PDS has yet to be determined. We report the case of a 71-year-old man with a PDS with perineural invasion on the scalp, with no recurrence one-year post-treatment with MMS and adjuvant radiation therapy. In contrast to wide local excision, MMS offers complete margin control and tissue preservation, which helps minimize scarring and morbidity. The comparative efficacy of MMS versus wide local excision in the treatment of PDS with and without radiation remains unknown and warrants further investigation.

BACKGROUND:As more people become vaccinated against the SARS-CoV-2 virus, reports of delayed cutaneous hypersensitivity reactions are beginning to emerge. METHODS:In this IRB-approved retrospective case series, biopsies of potential cutaneous adverse reactions from the Pfizer-BioNTech or Moderna mRNA vaccine were identified and reviewed. Clinical information was obtained through the requisition form, referring clinician, or medical chart review. RESULTS:Twelve cases were included. Histopathological features from two injection site reactions showed a mixed-cell infiltrate with eosinophils and a spongiotic dermatitis with eosinophils. Three biopsies came from generalized eruptions that demonstrated interface changes consistent with an exanthematous drug reaction. Three biopsies revealed a predominantly spongiotic pattern, consistent with eczematous dermatitis. Small vessel vascular injury was seen in two specimens, which were diagnosed as urticarial vasculitis and leukocytoclastic vasculitis, respectively. There were two cases of new-onset bullous pemphigoid supported by histopathological examination and direct immunofluorescence studies. Eosinophils were seen in 10 cases. CONCLUSIONS:Dermatopathologists should be aware of potential cutaneous adverse reactions to mRNA-based COVID-19 vaccines. Histopathological patterns include mixed-cell infiltrates, epidermal spongiosis, and interface changes. Eosinophils are a common finding but are not always present. Direct immunofluorescence studies may be helpful for immune-mediated cutaneous presentations such as vasculitis or bullous pemphigoid. This article is protected by copyright. All rights reserved.