Paediatric onset lymphomatoid papulosis: results of a multicentre retrospective cohort study, on behalf of the EORTC Cutaneous Lymphoma Tumours Group (CLTG).

BACKGROUND: Lymphomatoid Papulosis (LyP) is a rare cutaneous T-cell lymphoproliferative disorder. Comprehensive data on LyP in the paediatric population is scarce. OBJECTIVES: To characterize epidemiological, clinical, histopathological, and prognostic features of paediatric LyP. METHODS: This was a retrospective, multicentre international cohort study including 87 cases of children and adolescents with LyP diagnosed between 1998 and 2022. Patients aged ≤ 18 years old at disease onset were included. Diagnosis was made in each centre based on clinical-pathological correlation. RESULTS: Eighty-seven patients from 12 centres were included. The mean age at onset was 7.0 years (range 3 months-18 years) with a male to female ratio of 2:1. The mean time between onset of first cutaneous lesions and diagnosis was 1.3 years (range 0-14 years). Initial misdiagnosis concerned 26.4% of patients. Initially, LyP was most often misdiagnosed as Pityriasis lichenoides et varioliformis acuta (PLEVA), insect bites, or mollusca contagiosa. Erythematous papules or papulonodules were the most frequent clinical presentation. Pruritus was specifically mentioned for 20.7% of patients. The main histological subtype was type A in 55.1% of the cases. If analysed, monoclonal TCR rearrangement was found in 76.5% of the skin biopsies. The overall survival rate was 100% with follow up at 5 years available for 33 patients and at 15 years for 8 patients. A development of associated haematological malignancy (HM) occurred in 9.6% of the cases (7/73), including four mycosis fungoides (MF) cases, one primary cutaneous anaplastic large cell lymphoma (pc-ALCL), one systemic ALCL and one case of acute myeloid leukaemia. If we compare incidence rates of cancer with the world 0-19 years old population from 2001-2010, we estimate a significantly higher risk of associated malignancy in general, occurring before the age of 19 years old with incidence rate ratio of 87.49 (CI 86.01-88.99). CONCLUSIONS: We report epidemiological data from a large international cohort of children and adolescents with LyP. Overall the prognosis of the disease is good, with excellent survival rates for all patients. Due to increased risk of associated HM, a long-term follow-up should be recommended for LyP patients.

Melanocyte Density in the Diagnosis of Melanoma In Situ in Sun-Damaged Skin.

ABSTRACT: Histologic differentiation between melanoma in situ in chronically sun-damaged skin (CSDS) [lentigo maligna (LM)] and CSDS without malignancy is difficult because signs of melanocyte activation and proliferation are found in both. A potentially reliable and quantifiable criterion is melanocyte density (MD). Here, we evaluated whether and to what extent MD allows the distinction between LM and CSDS, which is particularly relevant for the evaluation of borderline cases and surgical margins.Articles assessing MD in LM and/or CSDS were evaluated in a systematic review. The results were categorized and compared according to staining. Cutoff values were included whenever stated.Twenty articles matched the selection criteria. Six hundred forty-four samples of CSDS and 227 samples of LM were considered. In each individual study, mean MD scores were higher for LM than for CSDS. However, looking at the overall study situation, it becomes clear that the data are very heterogeneous and show overlaps. Therefore, no reliable orientation value can be derived. Only 1 article defined a cutoff value.The data of MD in LM in contrast to CSDS were sparse, and a defined cutoff value was only mentioned in 1 article for microphthalmia-associated transcription factor, which cannot yet be generalized. Especially regarding the importance for the definition of surgical resection margins, this unsatisfactory data set highlights the need for further studies. More precise diagnostic criteria could spare some patients extensive and possibly disfiguring surgery.

Lymphomatoid Papulosis With T-cell Receptor-Gamma Delta Expression: A Clinicopathologic Case-series of 26 Patients of an Underrecognized Immunophenotypic Variant of Lymphomatoid Papulosis.

Lymphomatoid papulosis (LyP) has several histopathologic presentations. LyP featuring gamma-delta (γδ) T-cell receptor expression may masquerade as and may be misdiagnosed as aggressive cutaneous T-cell lymphoma, particularly primary cutaneous γδ T-cell lymphoma (PCGDTL) or γδ mycosis fungoides. We performed a clinicopathologic analysis of the largest series of LyP featuring γδ T-cell expression. We identified 26 patients with a diagnosis of LyP with γδ T cells from our institutions, as well as through a comprehensive review of the literature, and characterized these cases. Most cases were treated with topical steroids or not treated at all. The majority of cases showed a CD4 - CD8 + phenotype and featured at least one cytotoxic marker. Histopathologic features included an intraepidermal or dermal infiltrate with large cells and frequent angiotropism. One case was initially misdiagnosed as PCGDTL, requiring further therapy. Our case series, the largest international cohort of γδ T cell predominant LyP cases, confirms marked clinicopathologic heterogeneity that may contribute to misdiagnosis, reasserting the need to identify classic clinical features, CD30 + T-cell components, and markers of cytotoxicity when dealing with this differential diagnosis. A limitation of this study includes somewhat limited follow-up, histologic, and immunophenotypic information for some cases.

Dermatopathology - Current status and development in German-speaking dermatology.

Dermatopathology has been an integral part of dermatology for more than 100 years and is essential for high quality patient care. In German-speaking countries, dermatologists can acquire an additional qualification in dermatopathology after appropriate further training. For many years, dermatopathological diagnostics has advanced far beyond morphology. Immunohistochemistry and molecular pathology are nowadays an essential part and a prerequisite for the preservation of our discipline. Due to the increasing implementation of digitalization and artificial intelligence, dermatopathology is forward-looking and offers an attractive working environment for young colleagues. Dermatopathology is also indispensable for research, and this fact should also be taken into account by creating academic positions and professorships in the future.

QuPath Analysis for CD30+ Cutaneous T-Cell Lymphoma.

BACKGROUND: Mycosis fungoides is the most common subtype of cutaneous T-cell lymphoma, in which the expression of cluster of differentiation 30 (CD30)+ subtype can now be treated with the CD30 antibody conjugate brentuximab vedotin. Diagnostic methods are based on immunohistochemical (IHC) staining followed by manual assessment by pathologists, which is always a subjective calculation. QuPath, an open-source software for digital pathology image analysis, satisfies the requirements of objective approaches. METHODS: Ten samples from mycosis fungoides patients with CD30 expression at different stages were stained for CD3 and CD30 by IHC staining, scanned, and quantitative analysis was performed using QuPath (version 2.1). Each slide was independently assessed by 3 board-certified dermatopathologists. RESULTS: Individual estimates for CD30+/CD3+ cells varied among the individual histopathologists (mean coefficient of variation, 0.46; range, 0-0.78). QuPath analysis showed excellent separation between the positively stained cells for CD3 and CD30 IHC and other cells and tissue structures, although the results correlated strongly with the respective mean estimates of the 3 histopathologists (Pearson-R 0.93). CONCLUSIONS: The results show a high interobserver variability evaluation of IHC markers, although quantitative image analysis offer a significant advantage for comparison. This is not only relevant for clinical routine but also especially critical in therapeutic studies addressing targeted molecules.

Subcellular compartmentalization of STIM1 for the distinction of Darier disease from Hailey-Hailey disease.

BACKGROUND AND OBJECTIVES: Darier disease (DD) and Hailey-Hailey disease (HHD) are rare disorders caused by mutations in the ATPase, Sarcoplasmic/Endoplasmic Reticulum Ca2+ Transporting 2 (ATP2A2) and ATPase Ca2+ Transporting Type 2C, Member 1 (ATP2C1) gene, respectively, which lead to a disturbance of calcium metabolism in keratinocytes. Clinically, this is reflected by an impairment of keratinization. Histologically, acantholysis with variable degrees of dyskeratosis and parakeratosis is observed. Both diseases can usually be differentiated clinically, histopathologically and genetically. However, their routine distinction might be challenging since some patients do not harbor ATP2A2 or ATP2C1 mutations. To solve this diagnostic challenge, we studied the differential expression of two proteins of store-operated calcium entry (SOCE), stromal interaction molecule 1 (STIM1) and calcium release-activated calcium modulator 1 (ORAI1), by immunohistochemistry. PATIENTS AND METHODS: Five individuals with ambiguous diagnostic findings and eight controls with an unambiguous diagnosis were studied clinically, histologically, genetically, and by immunohistochemistry for STIM1 and ORAI1. RESULTS: DD patients consistently showed a cytoplasmic STIM1 expression while patients with HHD revealed a membrane-associated staining pattern. In contrast, ORAI1 did not show a differential expression pattern. CONCLUSIONS: Our data suggest subcellular compartmentalization of STIM1 as novel biomarker for the distinction of the two disorders.

Intraindividual variability of CD30 expression in mycosis fungoides -implications for diagnostic evaluation and therapy.

AIMS: To evaluate the frequency, subcellular localization, and variability of CD30 expression in mycosis fungoides. METHODS: This retrospective multicenter study investigated 135 biopsy specimens of 95 patients with mycosis fungoides for CD30 expression and CD30 staining pattern in relation to histomorphologic criteria, eosinophils, and tumour stage. We used two different CD30 cutoffs: (i) any CD30 positivity (important for in-label treatment with an anti-CD30 antibody-based drug), and (ii) ≥10% (most commonly used cutoff in therapy studies). The histologic slides were digitally evaluated with a slide viewer. None of the patients were treated with an anti-CD30 antibody-based drug. RESULTS: We found any CD30 expression in 90% of the samples (tumour cells and tumour microenvironment). More than 60% of the samples had CD30 expression ≥10%. CD30 staining was predominantly cytoplasmic and membranous, a Golgi pattern was only found in three samples. In patients with multiple biopsies (69 samples), a highly variable CD30 expression was found, especially in biopsies taken at different timepoints. CD30 and eosinophils were more common in advanced disease stage and cytoplasmic CD30 staining in intraepidermal lymphocytes was significantly associated with the presence of eosinophils. CONCLUSIONS: 90% of mycosis fungoides biopsies showed CD30 expression and are principally eligible for anti-CD30-antibody treatment. Because of the high intraindividual variability, investigation of multiple tissue samples for CD30 expression improves the assessment of this therapeutic target. Analysis of only a single skin biopsy might lead to misinterpretation of CD30 and bears the risk of inadequate and potentially unfavourable therapeutic decisions.

Case Report: Acquired Haemophilia A Following mRNA-1273 Booster Vaccination Against SARS-CoV-2 With Concurrent Diagnosis of Pleomorphic Dermal Sarcoma.

While the global pandemic caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is still ongoing and new virus variants are emerging, there is a universal need for vaccines to protect individuals from severe complications and ideally control the pandemic by enabling herd immunity. Several vaccines against SARS-CoV-2 have been approved and are widely used to stem the recurring waves of coronavirus disease 2019 (COVID-19). Post-marketing surveillance is essential to record even rare safety issues related to these new vaccines. Among these issues, several autoimmune phenomena have been recorded in temporal association with and feasibly triggered by a vaccination. Acquired haemophilia A (AHA) is a rare condition characterized by new-onset haemorrhagic diathesis caused by an inhibitor of blood clotting factor VIII (FVIII), often in the elderly and most commonly associated with autoimmune or malignant disease. There have been a small number of AHA cases triggered by vaccinations, including those against SARS-CoV-2. We report the first case of AHA in temporal association with an mRNA-1273 booster vaccination. The diagnosis was made promptly, and the patient received appropriate care including immunosuppression using glucocorticoids, cyclophosphamide (CYC) and rituximab (RTX). The haemorrhage ceased after escalation of treatment, and the patient is recovering. Concurrent malignancy was initially ruled out using a wide scope of diagnostic tests, but pleomorphic dermal sarcoma (PDS) of the forehead occurred after initiation of specific AHA immunosuppressive treatment. Since large vaccination programs are ongoing worldwide and potential adverse events during post-marketing surveillance have been reported following vaccination against SARS-CoV-2, this case illustrates challenges in rare events occurring in association with SARS-CoV-2 vaccination and to proof a causal relationship. Therefore, there is an urgent need for reporting any events in association with SARS-CoV-2 vaccination, but also a crucial discussion about possible concurrent triggers and follow-up information about individual patients.

Melanocytic nevi in sentinel lymph nodes: association with cutaneous nevi and clinical relevance in patients with cutaneous melanomas.

PURPOSE: Melanocytic nevi in lymph nodes (NNs) are an important histological differential diagnosis of initial sentinel lymph node (SN) metastasis in melanoma. Our aim was to associate NN in SNs with clinicopathologic features and survival rates in 1, 250 patients with SN biopsy for melanoma. METHODS: To compare patients with present and absent NN, we used Fisher's exact test, Mann-Whitney U test, and multivariate logistic regression models in this retrospective observational study based on a prospectively maintained institutional database. RESULTS: NN prevalence in axillary, cervical, and groin SNs was 16.5%, 19.4%, and 9.8%, respectively. NN were observed in combination with all growth patterns of melanoma, but more frequently when the primary was histologically associated with a cutaneous nevus. We observed a decreasing NN prevalence with increasing SN metastasis diameter. Multiple logistic regression determined a significantly increased NN probability for SNs of the neck or axilla, for individuals with ≥ 50 cutaneous nevi, midline primary melanomas, and for individuals who reported non-cutaneous malignancies in their parents. Cancer in parents was also significantly more frequently reported by melanoma patients who had more than 50 cutaneous nevi. In SN-negative patients, NN indicated a tendency for slightly lower melanoma-specific survival. CONCLUSIONS: We found a highly significant association between NN diagnosis and multiple cutaneous nevi and provided circumstantial evidence that cutaneous nevi in the drainage area of lymph nodes are particularly important. The trend toward lower melanoma-specific survival in SN-negative patients with NN suggests that careful differentiation of SN metastases is important.