Multicenter prospective blinded melanoma detection study with a handheld elastic scattering spectroscopy device

Background

The elastic scattering spectroscopy (ESS) device (DermaSensor Inc., Miami, FL) is a noninvasive, painless, adjunctive tool for skin cancer detection.

Objectives

To investigate the performance of the ESS device in the detection of melanoma.

Methods

A prospective, investigator-blinded, multicenter study was conducted at 8 United States (US) and 2 Australian sites. All eligible skin lesions were clinically concerning for melanoma, examined with the ESS device, subsequently biopsied according to dermatologists' standard of care, and evaluated with histopathology. A total of 311 participants with 440 lesions were enrolled, including 44 melanomas (63.6% in situ and 36.4% invasive) and 44 severely dysplastic nevi.

Results

The observed sensitivity of the ESS device for melanoma detection was 95.5% (95% CI, 84.5% to 98.8%, 42 of 44 melanomas), and the observed specificity was 32.5% (95% CI, 27.2% to 38.3%). The positive and negative predictive values were 16.0% and 98.1%, respectively.

Limitations

The device was tested in a high-risk population with lesions selected for biopsy based on clinical and dermoscopic assessments of board-certified dermatologists. Most enrolled lesions were pigmented.

Conclusion

The ESS device's high sensitivity and NPV for the detection of melanoma suggest the device may be a useful adjunctive, point-of-care tool for melanoma detection.

Adenocarcinoma of anogenital mammary gland type arising from encapsulated papillary carcinoma: A rare vulvar tumor mimicking breast carcinoma

Anogenital mammary-like glands are normal structures of the anogenital region. Tumors originating from these glands often exhibit a striking resemblance to their mammary gland counterparts. Herein, we present a rare case of adenocarcinoma of mammary gland type in the vulva of a 69-year-old female. Histopathologic examination revealed a complex lesion, which included a large encapsulated papillary carcinoma (EPC) with associated invasive carcinoma of mammary gland type and ductal carcinoma in situ (DCIS). The invasive component consisted mostly of invasive ductal carcinoma of no special type, with a notable focus of invasive mucinous carcinoma. p40 immunostain demonstrated a lack of myoepithelial cells in both the EPC and invasive carcinoma, but such cells expressed p40 around the ducts involved by DCIS. The main component of this lesion, EPC, was characterized by a papillary proliferation within a cystic space surrounded by a fibrous capsule without a myoepithelial layer. The histopathologic features of anogenital EPC closely resemble cutaneous hidradenoma papilliferum. Indeed, there have been a few reports in the literature describing cases where in situ and invasive carcinoma arose from a preexisting hidradenoma papilliferum. As tumors of anogenital mammary-like glands bear a closer resemblance to breast lesions than to skin tumors, we recommend that they be aligned with the classification of well-established breast lesions rather than cutaneous adnexal tumors.

Pitfalls of PRAME Immunohistochemistry in a Large Series of Melanocytic and Nonmelanocytic Lesions With Literature Review

ABSTRACT

Preferentially expressed antigen in melanoma (PRAME) immunohistochemistry is currently used to facilitate distinction of benign and malignant melanocytic proliferations. We hypothesized that evaluation of 1 institution's experience with PRAME labeling in a large number of consecutive cases might elucidate additional strengths and potential pitfalls and reveal base rates of positivity versus negativity in 1 academic practice. Pathology reports for all specimens on which PRAME labeling was performed at our institution between January 2021 and May 2022 were retrieved from our database. Eighty percent of conventional malignant melanomas were labeled diffusely positive with PRAME; there were no significant differences in mean age, sex, site, Breslow depth, ulceration status, or American Joint Committee on Cancer pathological tumor stage when comparing diffusely PRAME-positive malignant melanomas with those that lack diffuse labeling. Although no banal melanocytic nevi were labeled with PRAME, 13% of dysplastic nevi were diffusely PRAME positive, with junctional proliferations, severe atypia, male gender, and older age being associated with PRAME positivity. As some but not all ambiguous melanocytic lesions in which malignancy could not be excluded based on morphology alone were diffusely PRAME positive, PRAME's accuracy in predicting malignancy remains unclear to the authors; further study is needed to assess the precision to which PRAME immunohistochemistry can separate benign borderline lesions from their malignant counterparts. Among nonmelanocytic lesions, some poorly differentiated tumors, including atypical fibroxanthomas, can be PRAME positive. This series underscores the importance of clinicopathologic correlation and shows that diffuse PRAME positivity is highest in conventional malignant melanomas (∼80%, or 8 of 10 lesions), is seen in about half of challenging borderline lesions at our institution, and can be observed in lesions diagnosed as dysplastic nevi by our group (∼10% or 1 in 10 lesions), as well as in rare poorly differentiated malignancies.

IRF8 in Conjunction With CD123 and CD20 to Distinguish Lupus Erythematosus Panniculitis From Subcutaneous Panniculitis-like T-Cell Lymphoma

Distinguishing lupus erythematosus panniculitis (LEP) from subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a diagnostic challenge with important clinical implications. Immunohistochemical expression of interferon regulatory factor 8 (IRF8) has been shown to highlight cells with plasmacytoid dendritic cell differentiation. Considering that the presence of plasmacytoid dendritic cells highlighted by CD123 immunolabeling is a well-described feature that supports LEP over SPTCL, we hypothesized that IRF8 immunohistochemistry can be used as a diagnostic test to improve accuracy in differentiating LEP from SPTCL. In this study, we assessed the expression of IRF8, CD123, and CD20 in 35 cutaneous biopsies from 31 distinct patients, which included 22 cases of LEP and 13 cases of SPTCL. We found that clusters of IRF8-positive cells within the dermis, and away from subcutaneous fat, could discriminate LEP from SPTCL ( P =0.005). Similarly, CD123-positive clusters in any location were observed in LEP but absent in all cases of SPTCL. In addition, we found that dermal CD20-predominant lymphoid aggregates could help discriminate LEP from SPTCL ( P =0.022). As individual assays, IRF8, CD123, and CD20 were highly specific (100%, 100%, and 92%, respectively) though poorly sensitive (45%, 29%, and 50%, respectively). However, a panel combining IRF8, CD123, and CD20, with at least 1 positive marker was more accurate than any individual marker by receiver operating characteristic curve analysis. Our study provides a rationale for potentially including IRF8 as part of an immunohistochemical panel composed of other currently available markers used to differentiate LEP from SPTCL.

PRAME-negativity in sclerosing nevi with pseudomelanomatous features supports classification as an indolent lesion

BACKGROUND

Some dysplastic nevi, termed sclerosing nevi with pseudomelanomatous features, may have florid fibroplasia associated with features that cause melanoma to be a prominent consideration in the differential diagnosis. PRAME (PReferentially expressed Antigen in MElanoma) immunohistochemistry (IHC) has been shown to be a useful marker in the distinction of melanoma and nevus. PRAME expression in such sclerosing nevi with pseudomelanomatous features has not been evaluated to our knowledge.

METHODS

Thirty-two sclerosing nevi with pseudomelanomatous features were stained with PRAME IHC, with positive labeling defined as staining of >75% of the cytomorphologically atypical lesional cells.

RESULTS

All 32 cases had variable cytologic atypia, bridging of elongated rete, fibroplasia, and a vertically oriented trizonal appearance. Some cases (23/32) had centrally located flattening of the rete ridge pattern bilaterally flanked by fibroplasia associated with elongated rete. PRAME labeling was negative (<1% labeling) in 28/32 cases. Four cases, also interpreted as having negative labeling with PRAME, showed only weak nuclear positivity of <50% of the melanocytes within the pseudomelanomatous foci. p16 staining was positive in 28/28 lesions.

CONCLUSIONS

Rare sclerosing nevi with pseudomelanomatous features (4/32; ~13%) had weak PRAME labeling of 25%-50% of atypical foci. Twenty-eight of 32 lesions had virtually no labeling with PRAME. PRAME results support classifying sclerosing nevi with pseudomelanomatous features as indolent lesions.

HIF-1 regulates pathogenic cytotoxic T cells in lupus skin disease

Cutaneous lupus erythematosus (CLE) is a disfiguring autoimmune skin disease characterized by an inflammatory infiltrate rich in T cells, which are strongly implicated in tissue damage. How these cells adapt to the skin environment and promote tissue inflammation and damage is not known. In lupus nephritis, we previously identified an inflammatory gene program in kidney-infiltrating T cells that is dependent on HIF-1, a transcription factor critical for the cellular and developmental response to hypoxia as well as inflammation-associated signals. In our present studies using a mouse model of lupus skin disease, we find that skin-infiltrating CD4+ and CD8+ T cells also express high levels of HIF-1. Skin-infiltrating T cells demonstrated a strong cytotoxic signature at the transcript and protein levels, and HIF-1 inhibition abrogated skin and systemic diseases in association with decreased T cell cytotoxic activity. We also demonstrate in human CLE tissue that the T cell-rich inflammatory infiltrate exhibited increased amounts of HIF-1 and a cytotoxic signature. Granzyme B-expressing T cells were concentrated at sites of skin tissue damage in CLE, suggesting relevance of this pathway to human disease.

IRF8 may be a useful marker for blastic plasmacytoid dendritic cell neoplasm, especially with weak CD123 expression

We highlight the utility of interferon regulatory factor 8 (IRF8), a novel marker of monocytic and dendritic cell lineages, in the diagnosis of a case of blastic plasmacytoid dendritic cell neoplasm (BPDCN) presenting initially in the skin. A 60-year-old male with a previous history of myelodysplastic syndrome presented with cutaneous nodules on chest and scalp. A punch biopsy specimen of a skin nodule showed a diffuse dermal infiltrate of atypical mononuclear cells. The neoplastic cells expressed CD4, CD56, CD43, and TdT but showed minimal reaction for TCL-1 and CD123, and were negative for CD34, CD117, and MPO, confounding the diagnosis. IRF8 performed in retrospect was strongly positive. A new punch biopsy specimen of a chest nodule showed the blastoid tumor cells were positive for TCL-1, CD4, and CD56, but dim CD123. Subsequent bone marrow involvement showed blastoid tumor cells with intense positivity for CD123, CD4, and CD56, which was supportive of the BPDCN diagnosis. BPDCN cases with weak or variable CD123 and TCL-1 expression represent a potential diagnostic pitfall. In a recent study, 15 cases of BPDCN showed uniformly strong staining for IRF8, while CD123 was dim or negative in 4 of these 15 cases. We suggest IRF8 may be a useful marker for BPDCN, especially in cases with weak or variable expression of CD123 and TCL1.

Association of Somatic ATP2A2 Damaging Variants With Grover Disease

Importance

Grover disease (GD), a truncal eruption that typically occurs in older individuals, is exacerbated by sweating, irradiation, cancers, medications, kidney failure, and organ transplantation. The pathobiology of GD remains unknown.

Objective

To determine if damaging somatic single-nucleotide variants (SNVs) are associated with GD.

Design, Setting, and Participants

In this retrospective case series, we identified consecutive patients from a dermatopathology archive over a 4-year period (January 2007 to December 2011) who had 1 biopsy with a clinical diagnosis of GD confirmed via histopathologic findings and another non-GD biopsy. Participant DNA was extracted from both biopsy tissues and sequenced to high depth with a 51-gene panel to screen for SNVs in genes previously associated with acantholysis and Mendelian disorders of cornification. Analysis took place between 2021 and 2023.

Main Outcomes and Measures

Comparative analysis of sequencing data from paired GD and control tissue was employed to identify SNVs predicted to affect gene function, which were exclusive to, or highly enriched in, GD tissue.

Results

Overall, 12 of 15 cases of GD (12 men and 3 women; mean [SD] age, 68.3 [10.0] years) were associated with C>T or G>A ATP2A2 SNVs in GD tissue; all were predicted to be highly damaging via combined annotation dependent depletion (CADD) scores, and 4 were previously associated with Darier disease. In 9 cases (75%), the GD-associated ATP2A2 SNV was absent from control tissue DNA, and in 3 cases (25%), ATP2A2 SNVs were enriched 4- to 22-fold in GD vs control tissue.

Conclusions and Relevance

In this case series study of 15 patients, damaging somatic ATP2A2 SNVs were associated with GD. This discovery expands the spectrum of acantholytic disorders associated with ATP2A2 SNVs and highlights the role of somatic variation in acquired disorders.

Interface change in early mycosis fungoides: A potential mimicker of benign dermatoses

BACKGROUND

Histopathologic features of interface dermatitis can occasionally be seen in mycosis fungoides (MF), particularly in early patch-stage disease.

MATERIALS AND METHODS

We identified six patients with MF whose early biopsy specimens showed such prominent interface dermatitis that a benign diagnosis was favored. All subsequent specimens were reviewed for these patients, and the histopathologic evolution of disease was documented. Immunohistochemistry (IHC) for CD2, CD3, CD4, CD5, CD7, CD8, CD30, and CD123 was performed retrospectively. Educational archives were reviewed to assess the incidence of interface dermatitis in biopsies otherwise diagnostic of MF.

RESULTS

A spectrum of vacuolar and lichenoid patterns of interface change was observed in this series of six patients eventually diagnosed as having MF, and was seen as a recurring pattern in multiple specimens over time. In retrospect, findings described in early MF such as lining up of lymphocytes along the dermal-epidermal junction within the basal layer, papillary dermal fibrosis, and intraepidermal lymphocyte atypia could be appreciated to varying degrees in the confounding specimens. CD123 was negative in all cases, putatively excluding a connective tissue disease (CTD). None of the early biopsies showed loss of pan-T antigens CD2, CD5, and CD7. Forty-six of 164 cases (28%) of MF in an archival study set showed varying degrees of interface dermatitis in the setting of otherwise diagnostic changes of MF.

CONCLUSIONS

Early MF can show prominent interface change and mimic inflammatory dermatoses. Histopathologic clues suggestive of MF should be carefully assessed, and IHC for CD123 may be helpful in distinguishing MF from CTD. Repeat biopsies over time may be necessary to arrive at a definitive diagnosis, in conjunction with ancillary studies and strong clinicopathologic correlation.

Dermatopathologic features of cutaneous squamous cell carcinoma and actinic keratosis: Consensus criteria and proposed reporting guidelines

BACKGROUND

There is considerable variation in the literature regarding the dermatopathologic diagnostic features of and reporting guidelines for actinic keratosis (AK) and cutaneous squamous cell carcinoma (cSCC).

OBJECTIVE

To develop consensus recommendations regarding diagnostic criteria, nomenclature, and reporting of AK and cSCC.

METHODS

Literature review and cross-sectional multiround Delphi process including an international group of expert dermatopathologists followed by a consensus meeting.

RESULTS

Consensus was achieved regarding the key dermatopathologic features necessary for diagnosing cSCC, AK, and associated variants; grading of degree of cellular differentiation in cSCC; utility of immunohistochemistry for diagnosis of cSCC; and pathologic features that should be reported for cSCC and AK.

LIMITATIONS

Consensus was not achieved on all questions considered.

CONCLUSION

Despite the lack of clarity in the literature, there is consensus among expert dermatopathologists regarding diagnostic criteria and appropriate reporting of AK and cSCC. Widespread implementation of these consensus recommendations may improve communication between dermatopathologists and clinicians, facilitating appropriate treatment of AK and cSCC.

PRAME immunohistochemistry can distinguish melanocytic pseudonests of lichenoid reactions from melanoma in situ

BACKGROUND

Distinguishing melanocytic pseudonests encountered in lichenoid dermatoses or lichenoid keratoses from melanoma in situ (MIS) with brisk lichenoid inflammation can prove challenging.

METHODS

We designed a case-control study to evaluate the accuracy metrics of PRAME immunohistochemistry to distinguish melanocytic pseudonests in lichenoid dermatoses or keratoses from inflamed MIS. Immunostaining for PRAME was performed on paraffin-embedded formalin-fixed diagnostic tissue using a rabbit monoclonal antibody to PRAME (Abcam), with a 1:3200 dilution on a Leica Bond detection system.

RESULTS

Our search identified 21 cases of melanocytic pseudonests (n = 21, 46%) encountered in lichenoid dermatoses and 24 cases of inflamed MIS (n = 24, 53%). Each method of evaluating PRAME immunohistochemistry (PRAME+ clusters, PRAME % of melanocytes by four categories and PRAME+ melanocyte counts per linear mm of epidermal basal layer) showed statistically significant differences between the MIS and the pseudonest cohorts (respectively, p < 0.001; p < 0.001; and p < 0.001). Receiver operating characteristics analysis for PRAME+ melanocyte counts per linear mm of epidermal basal layer revealed an area under the curve of 0.9 ± 0.05 (95% confidence interval 0.9-1.0). When determining an optimal cut-off point for the best Youden index [sensitivity (%) + specificity (%) - 100], the cut-off of 1.0 PRAME+ melanocytes per linear mm showed a sensitivity of 79.2% and specificity of 85.7% (Youden index 0.65) to distinguish MIS from pseudonests.

CONCLUSION

PRAME immunohistochemistry may constitute an additional tool for this challenging differential diagnosis.

Inguinal patch in mpox (monkeypox) virus infection and eccrine syringometaplasia: report of two cases with in situ hybridization and electron microscopy

We report two cases of cutaneous mpox virus infection (formerly known as “monkeypox”), one of which presented with unusual clinical findings, and demonstrate their histopathologic, RNA in situ hybridization and ultrastructural characteristics. We observed in two patients with PCR-confirmed mpox virus infection squamous syringometaplasia of the eccrine ducts, a finding that can aid in recognizing this disease and is explained by the demonstration of viral mRNA within eccrine epithelium by in situ hybridization.

Lichenoid dermatoses with pseudomelanocytic nests vs inflamed melanoma in situ: A comparative study

AIMS

Pseudomelanocytic nests or "pseudonests" arising in lichenoid dermatoses can be a diagnostic pitfall for melanoma in situ (MIS), especially on sun-damaged skin. We sought to evaluate histopathological features that may be helpful in distinguishing this benign process from inflamed MIS.

METHODS

Ten biopsy specimens containing pseudomelanocytic nests within lichenoid dermatoses and twenty cases of inflamed MIS were retrospectively reviewed. Cases with pseudomelanocytic nests represented either a rash (n = 6) or a discrete non-melanocytic lesion, such as lichenoid keratosis (n = 4).

RESULTS

All cases with pseudomelanocytic nests showed nests of microphthalmia-associated transcription factor-positive cells at the dermoepidermal junction (DEJ) with interface changes and lichenoid inflammation. Pagetoid scatter, confluence of solitary melanocytes at the DEJ and significant cytologic atypia was not seen in any of these cases. In contrast, all cases of inflamed MIS demonstrated confluence of single melanocytes at the DEJ with cytologic atypia (P < 0.001) and 18/20 cases showed pagetoid scatter of melanocytes (P = 0.001).

CONCLUSIONS

Our results show that, of the different histopathological features assessed, confluent growth and pagetoid scatter of atypical melanocytes were seen in most cases of inflamed MIS but were absent in all cases with pseudomelanocytic nests. Therefore, in addition to clinicopathological correlation, these features may be useful in differentiating pseudomelanocytic nests arising in lichenoid dermatoses from inflamed MIS.

Cytokine RNA In Situ Hybridization Permits Individualized Molecular Phenotyping in Biopsies of Psoriasis and Atopic Dermatitis

Detection of individual cytokines in routine biopsies from patients with inflammatory skin diseases has the potential to personalize diagnosis and treatment selection, but this approach has been limited by technical feasibility. We evaluate whether a chromogen-based RNA in situ hybridization approach can be used to detect druggable cytokines in psoriasis and atopic dermatitis. A series of psoriasis (n = 20) and atopic dermatitis (n = 26) biopsies were stained using RNA in situ hybridization for IL4, IL12B (IL-12/23 p40), IL13, IL17A, IL17F, IL22, IL23A (IL-23 p19), IL31, and TNF (TNF-α). NOS2 and IFNG, canonical psoriasis biomarkers, were also included. All 20 of the psoriasis cases were positive for IL17A, which tended to be the predominant cytokine, although some cases had relatively higher levels of IL12B, IL17F, or IL23A. The majority of cytokine expression in psoriasis was epidermal. A total of 22 of 26 atopic dermatitis cases were positive for IL13, also at varying levels; a subset of cases had significant IL4, IL22, or IL31 expression. Patterns were validated in independent bulk RNA-sequencing and single-cell RNA-sequencing datasets. Overall, RNA in situ hybridization for cytokines appears highly specific with virtually no background staining and may allow for individualized evaluation of treatment-relevant cytokine targets in biopsies from patients with inflammatory skin disorders.

Leukocytoclastic Vasculitis and Microvascular Occlusion: Key Concepts for the Working Pathologist

Although clinicians often put vasculitis and microvascular occlusion in the same differential diagnosis, biopsy findings often are either vasculitis or occlusion. However, both vasculitis and occlusion are present in some cases of levamisole-associated vasculopathy and certain infections. Depth of dermal involvement and vessel size should be reported, because superficial and deep small vessel leukocytoclastic vasculitis and/or involvement of medium-sized vessels may be associated with systemic disease. Microvascular occlusion of vessels in the fat should prompt consideration of calciphylaxis. Clues to ultimate clinical diagnosis can be garnered from depth of involvement, size of vessels affected, and presence of both vasculitis and occlusion.

Cutaneous Involvement in Plasma Cell Myeloma

OBJECTIVES

Plasma cell myeloma (PCM) involving skin is rare and occurs in 1% to 4% of patients with PCM. We evaluated the clinicopathologic features, cytogenetic findings and clinical follow-up in a series of PCM cases with cutaneous involvement.

METHODS

Cases of PCM with cutaneous involvement were retrospectively reviewed with clinical data.

RESULTS

Skin involvement in PCM occurred in older individuals (mean, 75 years) and was more frequent in men (7/10 patients). All cases showed bone marrow involvement preceding the cutaneous lesions. Histopathologically, the infiltrate was plasmacytic (n = 5) or primitive or plasmablastic (n = 4), and 1 case showed predominantly lymphoplasmacytic features with cyclin D1 immunoreactivity and CCND1 gene rearrangement. Concurrent amyloid deposition was seen in one biopsy, and another case demonstrated coexisting squamous cell carcinoma. The most common immunophenotype was CD138+, CD20-, and CD56+ with light chain restriction. Cytogenetic analysis (available for 7 cases) showed multiple hyperdiploid abnormalities. Follow-up was available for 8 cases (mean, 42 months; range, 11-156 months) and showed short-term disease-related death in 7 of 8 patients.

CONCLUSIONS

Cutaneous involvement in PCM demonstrates a diverse cytomorphologic spectrum with plasmacytic, plasmablastic, or lymphoplasmacytic features and may show concurrent amyloid deposition or neoplasms such as squamous cell carcinoma. Cutaneous involvement typically occurs late in the course of the disease and likely portends poor outcome.

Discordant anti-SARS-CoV-2 spike protein and RNA staining in cutaneous perniotic lesions suggests endothelial deposition of cleaved spike protein

BACKGROUND

Prior studies have shown the presence of immunohistochemical staining for the SARS-CoV-2 spike protein (SP) in endothelial cells and eccrine epithelium of acral perniosis classified as "COVID toes." Yet, other studies have been unable to detect SARS-CoV-2 RNA in skin biopsies of "COVID toes" by reverse-transcriptase polymerase chain reaction testing.

OBJECTIVE

In order to address these apparently conflicting findings, we compared detection of SARS-CoV-2 SP, through RNA in situ hybridization (ISH) vs immunohistochemistry (IHC), in skin biopsies of acral perniotic lesions presenting during the COVID-19 pandemic.

RESULTS

Three of six cases showed positive immunohistochemical labeling of endothelial cells, with one of three cases with sufficient depth also having labeling of eccrine glands, using an anti-SP SARS-CoV-2 antibody. These three cases positive with IHC were negative for SP by RNA ISH.

CONCLUSION

While the gold standard for detection of SARS-CoV-2 in tissue sections has yet to be determined, the detection of SARS-CoV-2 SP alone without spike RNA suggests that cleaved SP may be present in cutaneous endothelial cells and eccrine epithelium, providing a potential pathogenetic mechanism of COVID-19 endotheliitis.

PD-1H (VISTA)-mediated suppression of autoimmunity in systemic and cutaneous lupus erythematosus

Systemic lupus erythematosus (SLE) and discoid lupus erythematosus (DLE) of the skin are autoimmune diseases characterized by inappropriate immune responses against self-proteins; the key elements that determine disease pathogenesis and progression are largely unknown. Here, we show that mice lacking immune inhibitory receptor VISTA or programmed death-1 homolog (PD-1H KO) on a BALB/c background spontaneously develop cutaneous and systemic autoimmune diseases resembling human lupus. Cutaneous lupus lesions of PD-1H KO mice have clustering of plasmacytoid dendritic cells (pDCs) similar to human DLE. Using mass cytometry, we identified proinflammatory neutrophils as critical early immune infiltrating cells within cutaneous lupus lesions of PD-1H KO mice. We also found that PD-1H is highly expressed on immune cells in human SLE, DLE lesions, and cutaneous lesions of MRL/lpr mice. A PD-1H agonistic monoclonal antibody in MRL/lpr mice reduces cutaneous disease, autoantibodies, inflammatory cytokines, chemokines, and immune cell expansion. Furthermore, PD-1H on both T cells and myeloid cells including neutrophils and pDCs could transmit inhibitory signals, resulting in reduced activation and function, establishing PD-1H as an inhibitory receptor on T cells and myeloid cells. On the basis of these findings, we propose that PD-1H is a critical element in the pathogenesis and progression of lupus, and PD-1H activation could be effective for treatment of systemic and cutaneous lupus.

Perniosis during the COVID-19 pandemic: Negative anti-SARS-CoV-2 immunohistochemistry in six patients and comparison to perniosis before the emergence of SARS-CoV-2

BACKGROUND

Acral inflammatory lesions that have some resemblance to idiopathic or autoimmune-associated perniosis (chilblains) have been described in multiple countries during the COVID-19 pandemic.

METHODS

We examined histopathologic findings in six consecutive such cases from five patients received in mid-May to mid-June of 2020, evaluating immunohistochemical staining for the SARS-CoV-2 nucleocapsid protein. We compared these six cases to eight cases diagnosed as perniosis between January and June of 2019.

RESULTS

Five of six lesions with perniosis-like histopathology during the COVID-19 pandemic had distinctive tight cuffing of lymphocytes; intravascular material was present in one case. SARS-CoV-2 immunohistochemical staining using an antibody directed at the nucleocapsid protein was negative in all six cases. Only one of eight specimens with microscopic findings of perniosis received prior to the COVID-19 pandemic had tightly cuffed perivascular lymphocytes, and none had obvious intravascular occlusion.

CONCLUSIONS

A tightly cuffed pattern of perivascular lymphocytes is a feature of perniosis during the COVID-19 pandemic. The absence of SARS-CoV-2 nucleocapsid protein in these cases suggests against the virus being directly present in these lesions.

A detailed analysis of the distribution, morphology, and histopathology of complex purpura in hospitalized patients: A case series of 68 patients

BACKGROUND

Purpura in inpatients commonly leads to dermatologic consultation. The differential diagnosis is broad and algorithms are intricate.

OBJECTIVE

We evaluated inpatient consultations for complex purpura to document the most common diagnoses and to validate the true diagnostic utility of histopathology, clinical morphology, and distribution.

METHODS

We reviewed a case series of 68 inpatients during a 4-year period with a dermatologic consultation for purpura and biopsy findings of vasculitis or microvascular occlusion.

RESULTS

Key features of complex purpura are nonbranching (round) versus branching (retiform) morphology, dependent versus acral or generalized distribution, and leukocytoclastic vasculitis versus microvascular occlusion (with emphasis on depth of involvement). Dependent nonbranching purpura with only superficial vessels involved by leukocytoclastic vasculitis was most often due to IgA vasculitis or cutaneous single-organ small-vessel vasculitis. In contrast, deeper involvement by leukocytoclastic vasculitis was suggestive of systemic disease (eg, antineutrophil cytoplasmic antibody-associated vasculitis). Branching purpura was concerning, with greater than 90% sensitivity and specificity for microvascular occlusion and associated high mortality (≈50%). The majority of patients who died had acral branching lesions.

LIMITATIONS

Small sample size, inpatients at a tertiary care center, and retrospective nature are some limitations.

CONCLUSION

Nonbranching dependent purpura corresponded to leukocytoclastic vasculitis, with the most common diagnoses being IgA vasculitis or skin-limited small-vessel vasculitis; patients with deep involvement often had systemic diseases. In this series, branching purpura was due to microvascular occlusion rather than medium-vessel vasculitis, and had associated high mortality.

Intravascular Large B-Cell Lymphoma: Clinical and Histopathologic Findings

Intravascular large B-cell lymphoma (IVLBCL) is a rare subset of extranodal non-Hodgkin lymphoma characterized by neoplastic lymphocytes within the lumina of small to medium-sized blood vessels. IVLBCLs are B-cell tumors that can present in essentially any organ system, including the skin. Cutaneous manifestations vary greatly and can mimic other skin disease which may delay diagnosis; in the absence of skin lesions, blind skin biopsies can be utilized for diagnosis. Early studies suggested that IVLBCL is a very aggressive lymphoma with high overall mortality rate and short survival times. However, earlier diagnosis and use of new treatment modalities have shown promise in recent studies. This case series illustrates the heterogeneity of clinical and pathologic presentations of this uncommon lymphoma.

Mutations in KRT10 in epidermolytic acanthoma

BACKGROUND

Epidermolytic acanthoma (EA) is a rare acquired lesion demonstrating a characteristic histopathological pattern of epidermal degeneration referred to as epidermolytic hyperkeratosis (EHK). On histopathological analysis, EA appears nearly identical to inherited EHK-associated dermatoses such as epidermolytic ichthyosis and ichthyosis bullosa of Siemens. While it has been speculated that EA is caused by mutations in KRT10, KRT1, or KRT2 found in these inherited dermatoses, none have yet been identified. Herein, we aim to identify the contributions of keratin mutations to EA.

METHODS

Using genomic DNA extracted from paraffin-embedded samples from departmental archives, we evaluated a discovery cohort using whole-exome sequencing (WES) and assessed remaining samples using Sanger sequencing screening and restriction fragment length polymorphism (RFLP) analysis.

RESULTS

DNA from 16/20 cases in our sample was of sufficient quality for polymerase chain reaction amplification. WES of genomic DNA from lesional tissue revealed KRT10 c.466C > T, p.Arg156Cys mutations in 2/3 samples submitted for examination. RFLP analysis of these samples as well as eight additional samples confirmed the mutations identified via WES and identified four additional cases with Arg156 mutations. In sum, 6/11 screened cases showed hotspot mutation in KRT10.

CONCLUSIONS

Hotspot mutations in the Arg156 position of KRT10, known to cause epidermolytic ichthyosis, also underlie EA.

Histopathologic findings characteristic of CARD14-associated papulosquamous eruption

BACKGROUND

Pathogenic mutations in caspase recruitment domain-containing protein 14 (CARD14) lead to CARD14-associated papulosquamous eruption, which shares clinicopathologic findings with psoriasis and pityriasis rubra pilaris. We aimed to describe distinguishing histopathologic features of CARD14-associated papulosquamous eruption.

METHODS

This retrospective study examined the histopathologic features of specimens from patients with confirmed CARD14-associated papulosquamous eruption and adult patients with plaque psoriasis and pityriasis rubra pilaris.

RESULTS

Lesional skin biopsies from patients with CARD14-associated papulosquamous eruption consistently showed alternating checkerboard parakeratosis and orthokeratosis, acanthosis without acantholysis, and dilated vessels in the dermal papillae, with some cases also showing follicular plugging.

CONCLUSION

CARD14-associated papulosquamous eruption has a range of findings, with a predominance of features typically associated with pityriasis rubra pilaris.

Distinguishing pustular psoriasis and acute generalized exanthematous pustulosis on the basis of plasmacytoid dendritic cells and MxA protein

BACKGROUND

Distinguishing acute generalized exanthematous pustulosis (AGEP) and pustular psoriasis (PS) can be challenging. Staining for plasmacytoid dendritic cells, or PDCs (producer of IFN-α/β), and MxA (an IFN-α/β inducible protein) may help discriminate these entities.

METHODS

Forty-three cases of AGEP and PS were compiled from two academic institutions. All cases were examined for CD123+ PDCs, eosinophils, acanthosis, papillomatosis, suprapapillary plate thinning, tortuous dilated capillaries, single necrotic keratinocytes, papillary dermal edema, vasculitis, eosinophil exocytosis, intraepidermal pustules, and subcorneal pustules. A subset of cases (n = 26) was stained for MxA.

RESULTS

Perivascular and intraepidermal PDCs, dilated tortuous vessels, and MxA expression in the dermal inflammatory infiltrate were significantly (P < 0.05) in favor of a diagnosis of PS. The absence of PDCs and presence of eosinophils favored a diagnosis of AGEP (P < 0.05).

CONCLUSIONS

We found compelling evidence for the use of CD123 to highlight PDCs in these cases. The presence of PDCs and expression of MxA in dermal inflammatory infiltrate, as well as absence of eosinophils and presence of tortuous dilated capillaries favored a diagnosis of PS. Expression of MxA in the dermal infiltrate corresponds with a Th1 pathway in PS and may indicate a Th1 component in the early initial phase of AGEP.

Solitary and multiple epidermolytic acanthoma: A demographic and clinical study of 131 cases

BACKGROUND

Epidermolytic acanthoma (EA) is a rare, benign acquired cutaneous keratosis displaying epidermolytic hyperkeratosis in more than 50% of its surface. Because of the sparsity of comprehensive studies, little is known on the patient demographics and clinical characteristics of this uncommon entity. We wish to comprehensively characterize the clinical and demographic features of EA and to differentiate it from its mimickers.

METHODS

We carried out a retrospective review of 131 cases of EA, recorded clinical and histopathologic features and performed linear regression of yearly incidence rates to assess for possible under-reporting of this entity.

RESULTS

EA affected both genders equally. We found 9.08 cases per 100 000 biopsy specimens per year and linear regression analysis showed significantly decreasing incidence rates. Analysis of the anatomical site distribution of EA lesions showed a more frequent genital location in men (39.1% of cases in men, as compared to 11.3% for women). Contrary to previous studies, lesions were most frequently single (91.7%) and the mean age of presentation was 57.8 years.

CONCLUSION

The presented largest case series to-date indicates that EA is probably an underdiagnosed entity and establishes the demographic and clinical features of EA.

Dermatomyositis: Histopathologic findings of parakeratosis and dermal edema revisited

The cutaneous manifestations of dermatomyositis range from classical in the case of heliotrope rash and Gottron papules to less common papulosquamous and edematous/vesiculobullous lesions; histopathologic descriptions are dominated by interface dermatitis. We present a case of dermatomyositis with a combination of common and rare skin findings, both clinically and histologically. Increased awareness of papulosquamous and edematous lesions of dermatomyositis can help direct patient care. Although uncommon, confluent parakeratosis and dermal edema can be manifestations of dermatomyositis.

PD-L1 Prevents the Development of Autoimmune Heart Disease in Graft-versus-Host Disease

Effector memory T cells (T_EM) are less capable of inducing graft-versus-host disease (GVHD) compared with naive T cells (T_N). Previously, in the TS1 TCR transgenic model of GVHD, wherein TS1 CD4 cells specific for a model minor histocompatibility Ag (miHA) induce GVHD in miHA-positive recipients, we found that cell-intrinsic properties of TS1 T_EM reduced their GVHD potency relative to TS1 T_N Posttransplant, TS1 T_EM progeny expressed higher levels of PD-1 than did TS1 T_N progeny, leading us to test the hypothesis that T_EM induce less GVHD because of increased sensitivity to PD-ligands. In this study, we tested this hypothesis and found that indeed TS1 T_EM induced more severe skin and liver GVHD in the absence of PD-ligands. However, lack of PD-ligands did not result in early weight loss and colon GVHD comparable to that induced by TS1 T_N, indicating that additional pathways restrain alloreactive T_EM TS1 T_N also caused more severe GVHD without PD-ligands. The absence of PD-ligands on donor bone marrow was sufficient to augment GVHD caused by either T_EM or T_N, indicating that donor PD-ligand-expressing APCs critically regulate GVHD. In the absence of PD-ligands, both TS1 T_EM and T_N induced late-onset myocarditis. Surprisingly, this was an autoimmune manifestation, because its development required non-TS1 polyclonal CD8⁺ T cells. Myocarditis development also required donor bone marrow to be PD-ligand deficient, demonstrating the importance of donor APC regulatory function. In summary, PD-ligands suppress both miHA-directed GVHD and the development of alloimmunity-induced autoimmunity after allogeneic hematopoietic transplantation.

Tumor Necrosis Factor-α and IL-17A Activation Induces Pericyte-Mediated Basement Membrane Remodeling in Human Neutrophilic Dermatoses

Sweet syndrome (SS) is a prototypical neutrophilic dermatosis, a class of inflammatory diseases marked by elevated levels of tumor necrosis factor (TNF)-α and IL-17A, pathologic neutrophil recruitment, and microvascular remodeling. Histologic analyses of four matrix proteins-collagen I and IV, laminin, and fibronectin-in skin biopsies of patients with SS reveal that the basement membrane of dermal postcapillary venules undergoes changes in structure and composition. Increased neutrophil recruitment in vivo was associated with increases in collagen IV, decreases in laminin, and varied changes in fibronectin. In vitro studies using TNF-α and IL-17A were conducted to dissect basement membrane remodeling. Prolonged dual activation of cultured human pericytes with TNF-α and IL-17A augmented collagen IV production, similar to in vivo remodeling. Co-activation of pericytes with TNF-α and IL-17A also elevated fibronectin levels with little direct effect on laminin. However, the expression of fibronectin- and laminin-specific matrix metalloproteinases (MMPs), particularly MMP-3, was significantly up-regulated. Interactions between pericytes and neutrophils in culture yielded even higher levels of active MMPs, facilitating fibronectin and laminin degradation, and likely contributing to the varied levels of detectable fibronectin and the decreases in laminin observed in vivo. These data indicate that pericyte-neutrophil interactions play a role in mediating microvascular changes in SS and suggest that targeting MMP-3 may be effective in protecting vascular wall integrity.

Myeloid Cell-Derived HIF-1α Promotes Control of Leishmania major

Hypoxia-inducible factor-1α (HIF-1α), which accumulates in mammalian host organisms during infection, supports the defense against microbial pathogens. However, whether and to what extent HIF-1α expressed by myeloid cells contributes to the innate immune response against Leishmania major parasites is unknown. We observed that Leishmania-infected humans and L. major-infected C57BL/6 mice exhibited substantial amounts of HIF-1α in acute cutaneous lesions. In vitro, HIF-1α was required for leishmanicidal activity and high-level NO production by IFN-γ/LPS-activated macrophages. Mice deficient for HIF-1α in their myeloid cell compartment had a more severe clinical course of infection and increased parasite burden in the skin lesions compared with wild-type controls. These findings were paralleled by reduced expression of type 2 NO synthase by lesional CD11b⁺ cells. Together, these data illustrate that HIF-1α is required for optimal innate leishmanicidal immune responses and, thereby, contributes to the cure of cutaneous leishmaniasis.

NLRC4 suppresses melanoma tumor progression independently of inflammasome activation

Members of the NLR family can assemble inflammasome complexes with the adaptor protein ASC and caspase-1 that result in the activation of caspase-1 and the release of IL-1β and IL-18. Although the NLRC4 inflammasome is known to have a protective role in tumorigenesis, there is an increased appreciation for the inflammasome-independent actions of NLRC4. Here, we utilized a syngeneic subcutaneous murine model of B16F10 melanoma to explore the role of NLRC4 in tumor suppression. We found that NLRC4-deficient mice exhibited enhanced tumor growth that was independent of the inflammasome components ASC and caspase-1. Nlrc4 expression was critical for cytokine and chemokine production in tumor-associated macrophages and was necessary for the generation of protective IFN-γ-producing CD4+ and CD8+ T cells. Tumor progression was diminished when WT or caspase-1-deficient, but not NLRC4-deficient, macrophages were coinjected with B16F10 tumor cells in NLRC4-deficient mice. Finally, examination of human primary melanomas revealed the extensive presence of NLRC4+ tumor-associated macrophages. In contrast, there was a paucity of NLRC4+ tumor-associated macrophages observed in human metastatic melanoma, supporting the concept that NLRC4 expression controls tumor growth. These results reveal a critical role for NLRC4 in suppressing tumor growth in an inflammasome-independent manner.

Koebnerization of Hailey-Hailey disease into a cutaneous drug eruption of acute generalized exanthematous pustulosis associated with systemic symptoms

We describe a 65-year-old Caucasian female with well-controlled Hailey-Hailey disease (HHD) who developed acute generalized exanthematous pustulosis (AGEP) with severe systemic symptoms. Despite sparing of the patient's intertriginous skin, histopathologic evidence of HHD was observed in all biopsies, suggestive of a unique koebernization phenomenon of HHD to areas of cutaneous drug eruption. While internal organ involvement is less commonly reported in AGEP, there are an increasing number of patients with signs and symptoms suggestive of an AGEP/drug reaction with eosinophilia and systemic symptoms (DRESS) spectrum of cutaneous drug disorders. Early diagnosis of patients with AGEP and systemic symptoms is critical so that these patients may receive prompt and aggressive systemic therapy to decrease the risk of end organ damage and improve overall morbidity and mortality.

Histopathologic features of multiple cutaneous squamous cell carcinomas of the lower extremity

Recent studies suggest cutaneous squamous cell carcinomas (SCCs) of the leg, particularly those occurring multiply in sun exposed skin of nonimmunosuppressed women, are a distinct clinical subtype. There are few reports of the histopathologic features of this subtype. A retrospective chart review of 4 patients with multiple SCCs on the leg was performed and a total of 35 biopsies from the legs examined. Histopathologically, the tumors lacked adjacent actinic keratosis (AK) and often had adjacent basaloid retiform proliferations. Most lesions (all but one) were well differentiated and about 40% could be classified histopathologically as keratoacanthoma. Perineural invasion was absent in all but one case. Using the American Joint Committee on Cancer (AJCC) staging criteria for SCC, 21 tumors were Stage I, and 9 Stage II. During 7-10 years of follow-up, no recurrence or metastasis occurred. Patients with multiple SCCs on the lower extremities can have a range of histopathologic features, from keratoacanthoma-like to well-differentiated SCC.