The difficulty with measuring the largest melanoma tumour diameter in sentinel lymph nodes

Identification of sentinel node (SN) metastases can set the adjuvant systemic therapy indication for stage III melanoma patients. For stage IIIA patients, a 1.0 mm threshold for the largest SN tumour diameter is used. Therefore, uniform reproducible measurement of its size is crucial. At present, the number of deposits or their microanatomical sites are not part of the inclusion criteria for adjuvant treatment. The goal of the current study was to show examples of the difficulty of measuring SN melanoma tumour diameter and teach how it should be measured. Histopathological slides of SN-positive melanoma patients were retrieved using the Dutch Pathology Registry (PALGA). Fourteen samples with the largest SN metastasis around 1.0 mm were uploaded via tele-pathology and digitally measured by 12 pathologists to reflect current practice of measurements in challenging cases. Recommendations as educational examples were provided. Microanatomical location of melanoma metastases was 1 subcapsular, 2 parenchymal and 11 combined. The smallest and largest difference in measurements were 0.24 mm and 4.81 mm, respectively. 11/14 cases (78.6%) showed no agreement regarding the 1.0 mm cut-off. The median discrepancy for cases ≤5 deposits was 0.5 mm (range 0.24-0.60, n=3) and 2.51 mm (range 0.71-4.81, n=11) for cases with ≥6 deposits. Disconcordance in measuring SN tumour burden is correlated with the number of deposits. Awareness of this discordance in challenging cases, for example, cases with multiple small deposits, is important for clinical management. Illustrating cases to reduce differences in size measurement are provided.

Clinical, histopathological and molecular features of dedifferentiated melanomas: An EORTC Melanoma Group Retrospective Analysis

PURPOSE

Dedifferentiated melanoma (DedM) poses significant diagnostic challenges. We aimed to investigate the clinical, histopathological and molecular features of DedM. Methylation signature (MS) and copy number profiling (CNP) were carried out in a subgroup of cases.

PATIENTS AND METHODS

A retrospective series of 78 DedM tissue samples from 61 patients retrieved from EORTC (European Organisation for Research and Treatment of Cancer) Melanoma Group centres were centrally reviewed. Clinical and histopathological features were retrieved. In a subgroup of patients, genotyping through Infinium Methylation microarray and CNP analysis was carried out.

RESULTS

Most patients (60/61) had a metastatic DedM showing most frequently an unclassified pleomorphic, spindle cell, or small round cell morphology akin to undifferentiated soft tissue sarcoma, rarely associated with heterologous elements. Overall, among 20 successfully analysed tissue samples from 16 patients, we found retained melanoma-like MS in only 7 tissue samples while a non-melanoma-like MS was observed in 13 tissue samples. In two patients from whom multiple specimens were analysed, some of the samples had a preserved cutaneous melanoma MS while other specimens exhibited an epigenetic shift towards a mesenchymal/sarcoma-like profile, matching the histological features. In these two patients, CNP was largely identical across all analysed specimens, in line with their common clonal origin, despite significant modification of their epigenome.

CONCLUSIONS

Our study further highlights that DedM represents a real diagnostic challenge. While MS and genomic CNP may help pathologists to diagnose DedM, we provide proof-of-concept that dedifferentiation in melanoma is frequently associated with epigenetic modifications.

Revision of the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis Classification Schema for Melanocytic Lesions: A Consensus Statement

IMPORTANCE

A standardized pathology classification system for melanocytic lesions is needed to aid both pathologists and clinicians in cataloging currently existing diverse terminologies and in the diagnosis and treatment of patients. The Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) has been developed for this purpose.

OBJECTIVE

To revise the MPATH-Dx version 1.0 classification tool, using feedback from dermatopathologists participating in the National Institutes of Health-funded Reducing Errors in Melanocytic Interpretations (REMI) Study and from members of the International Melanoma Pathology Study Group (IMPSG).

EVIDENCE REVIEW

Practicing dermatopathologists recruited from 40 US states participated in the 2-year REMI study and provided feedback on the MPATH-Dx version 1.0 tool. Independently, member dermatopathologists participating in an IMPSG workshop dedicated to the MPATH-Dx schema provided additional input for refining the MPATH-Dx tool. A reference panel of 3 dermatopathologists, the original authors of the MPATH-Dx version 1.0 tool, integrated all feedback into an updated and refined MPATH-Dx version 2.0.

FINDINGS

The new MPATH-Dx version 2.0 schema simplifies the original 5-class hierarchy into 4 classes to improve diagnostic concordance and to provide more explicit guidance in the treatment of patients. This new version also has clearly defined histopathological criteria for classification of classes I and II lesions; has specific provisions for the most frequently encountered low-cumulative sun damage pathway of melanoma progression, as well as other, less common World Health Organization pathways to melanoma; provides guidance for classifying intermediate class II tumors vs melanoma; and recognizes a subset of pT1a melanomas with very low risk and possible eventual reclassification as neoplasms lacking criteria for melanoma.

CONCLUSIONS AND RELEVANCE

The implementation of the newly revised MPATH-Dx version 2.0 schema into clinical practice is anticipated to provide a robust tool and adjunct for standardized diagnostic reporting of melanocytic lesions and management of patients to the benefit of both health care practitioners and patients.

Adjuvant treatment of in-transit melanoma: Addressing the knowledge gap left by clinical trials

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Background: Few clinical trials address the efficacy of adjuvant systemic treatment in patients with ITM. This study describes the efficacy of adjuvant systemic therapy of ITM patients beyond the clinical trial setting. Methods: All stage III adjuvant-treated melanoma patients registered in the nationwide Dutch Melanoma Treatment Registry between 01-07-2018 and 31-12-2020 were included. Patients were divided into three groups: patients with ITM only, with ITM and nodal disease, and patients with nodal disease only. Differences in recurrence patterns were analysed. An exploratory analysis was performed for stage III patients who underwent surgical resection without adjuvant treatment. Recurrence-free survival (RFS) and overall survival (OS) at 12-months were assessed. Results: A total of 1037 stage III melanoma patients received adjuvant anti-PD-1 therapy, and 260 underwent surgical resection only. Of the adjuvant-treated patients, 16.9% had ITM only, 15.5% had ITM with nodal disease, and 66.8% had nodal disease only. Of the surgical resection only patients 20.4% had ITM only, 12.3% had ITM with nodal disease and 67.3% had nodal disease only. In the adjuvant-treated patients, 12-months RFS was comparable between patients with ITM only and patients with nodal disease only (71.1% vs. 72.2% respectively, p = 0.95), but significantly lower for patients with ITM and nodal disease (57.1%; ITM with nodal disease vs. ITM-only p = 0.01, and ITM with nodal disease vs. nodal disease only p < 0.01). Locoregional metastases occurred as first recurrence site in 72.7% of ITM-only patients, 42.9% of ITM and nodal disease patients and 38.9% of patients with nodal disease only, while distant recurrences occurred in 18.2% of patients with ITM only, in 36.7% of patients with ITM and nodal disease, and in 42.3% of patients with nodal disease only (p = 0.01). OS at 12-months was significantly higher for ITM-only patients compared to patients with ITM and nodal disease (97.7% vs. 90.6%, p < 0.01), and was better compared to patients with nodal disease only (97.7% vs. 94.4%, p = 0.05). OS at 12-months was comparable for patients with ITM and nodal disease and patients with nodal disease only (p = 0.19). In general, surgery-only ITM patients were older and had a worse performance score. 12-months RFS appeared worse compared to adjuvant-treated ITM patients (36.6% vs. 68.3%). In this group of surgery-only ITM patients OS at 12-months also appeared worse compared to adjuvant-treated ITM patients (89.7% vs. 95.5%). Conclusions: RFS rates in ITM-only patients are similar to non-ITM patients, while RFS in patients with ITM and nodal disease is shorter. Adjuvant-treated patients with ITM without nodal disease less often experience distant recurrences and have a superior OS compared to other adjuvant stage III patients. Our results suggest that other treatment strategies for ITM patients with nodal disease should be considered.

Management of checkpoint inhibitor toxicity and survival in patients with advanced melanoma

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Background: Management of checkpoint-inhibitor-induced immune-related adverse events (irAEs) is primarily based on expert opinion. Recent studies have suggested detrimental effects of immunosuppressive treatment with anti-TNF on checkpoint-inhibitor efficacy. Methods: Advanced melanoma patients experiencing grade ≥3 irAEs after treatment with first-line ipilimumab-nivolumab between 2015 and 2021 were included from the Dutch Melanoma Treatment Registry. Progression-free survival (PFS), overall survival (OS) and melanoma-specific survival (MSS) were analyzed according to toxicity management regimen. A cox proportional hazards model was used to account for the confounders age, sex, performance status, lactate dehydrogenase, site of metastases and type of irAE. Results: Out of 771 ipilimumab-nivolumab treated patients, 350 were treated with immunosuppression for severe irAEs. Of these patients, 235 received steroids only and 115 received steroids with second-line immunosuppressants consisting of anti-TNF, mycophenolic acid, tacrolimus and other immunosuppressants. Median PFS was significantly longer for patients treated with steroids (11.3 months) than for patients treated with steroids and second-line immunosuppressants (5.4 months; HR 1.43; 95%CI 1.07-1.90; p = 0.01). Median OS was also significantly longer for the steroids group (46.1 months) than for the steroids and second-line immunosuppressants group (22.5 months; HR 1.64; 95%CI 1.16-2.32; p = 0.005). Results for MSS were similar (not reached versus 28.8 months; HR 1.70; 95%CI 1.16-2.49; p = 0.006). Median PFS, OS and MSS are shown in Table 1. After adjustment for potential confounders, patients treated with steroids + second-line immunosuppressants showed a non-significant trend towards a higher risk of progression (HRadj 1.40; 95%CI 1.00-1.97; p = 0.05), a higher risk of death (HRadj 1.54; 95%CI 1.03-2.30; p = 0.04) and of melanoma-specific death (HRadj 1.62; 95%CI 1.04-2.51; p = 0.032) compared to the steroids group. Conclusions: Second-line immunosuppression for irAEs is associated with impaired PFS, OS, and MSS in advanced melanoma patients treated with first-line ipilimumab-nivolumab, irrespective of being anti-TNF or other second-line immunosuppressants. These findings stress the importance of assessing the effects of differential irAE management strategies, not only in melanoma but also in other tumor types. [Table: see text]

Is adjuvant treatment for melanoma in clinical practice comparable to trials? The first population-based results

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Background: Little is known about the outcome of adjuvant therapy in melanoma patients beyond the clinical trial setting. The Dutch Melanoma treatment Registry (DMTR) is a population-based registry, set up in July 2013 to monitor the safety and quality of melanoma care. Since 2019, adjuvant treated melanoma patients have also been registered in the DMTR, following approval and reimbursement of adjuvant treatment in the Netherlands in December 2018. Methods: Analyses were performed on melanoma patients treated with adjuvant anti-PD1 therapy included in the DMTR between 01-07-2018 and 31-12-2019. Descriptive statistics were used to analyze patient-, and treatment characteristics, and death as well as relapse rates. Results: Six hundred and fifty-seven patients treated with adjuvant systemic therapy were included in the DMTR. The majority (94%) of these patients was treated with anti-PD1. Twenty percent of the anti-PD1-treated patients developed grade ≥3 toxicity. Of the 279 patients with a minimum follow-up of one year after start of anti-PD1, 170 (61%) prematurely discontinued therapy. Relapse and death occurred in respectively, 38% and 12% of patients within one year of follow-up. Relapse was significantly more frequent in older patients, with high Breslow thickness and ulcerated melanomas. Conclusions: These data show more frequent premature discontinuation of adjuvant anti-PD1 in daily clinical practice than reported in the registration trials. Moreover, incidence of severe toxicity, relapse and death during adjuvant treatment appears higher in the real-world setting.

Efficacy of checkpoint inhibition in advanced acral melanoma

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Background: Recent data in Japanese patients suggest poor outcomes for anti-PD1 in acral melanoma (AM), with no data available on combination treatment. The objective of this study was to analyze the efficacy of anti-PD1 monotherapy and anti-PD1 and anti-CTLA4 combination therapy in these patients. Methods: Our study population consisted of patients registered in the nationwide prospective Dutch Melanoma Treatment Registry between 2014 and 2020. We calculated objective response rate (ORR) in all unresectable stage III and IV AM and nonacral cutaneous melanoma (NAM) patients treated with anti-PD1, and combination anti-PD1 and anti-CTLA4. Progression-free survival (PFS), and overall survival (OS) were estimated for first-line treated patients. A Cox proportional hazard analysis was performed to adjust for potential confounders. Results: Nighty-five AM patients received at least one dose of anti-PD1 monotherapy, of whom 58 (61%) as first-line treatment. ORR was 28% (complete response 11%; partial response 18%). Median PFS and OS in patients with first-line treatment were 5.5 months (95% CI 3.5-8.4) and 14 months (95% CI 9.3-25.0). In patients with NAM (n = 1259) ORR was 48% (complete response 18%; partial response 31%). Six-hundred and eighty-eight (55%) patients received anti-PD1 as first-line treatment. Median PFS was 11.7 months (95% CI 9.1-14.9) and median OS was 24 months (95% CI 20.0-29.3) in these patients. Older age, higher ECOG scores, elevated LDH levels, liver metastasis and brain metastasis were significantly associated with lower OS. After adjustment for covariates, acral subtype remained associated with shorter PFS (Hazard Ratio 1.76, 95% CI 1.25-2.48) and OS (Hazard Ratio 1.70, 95% CI 1.17-2.45). Twenty-four AM patients received at least one dose of anti-PD1 plus anti-CTLA4, of which 15 as first-line treatment. ORR was 25% (complete response 4%; partial response 20%). AM patients treated with first-line combination therapy had a median PFS of 3.8 months (95% CI 2.8-NR) and median OS of 7.63 months (95% CI 6.12-NR). ORR in NAM patients treated with combination therapy (n = 599) was 41% (complete response 8%; partial response 33%). Forty-six percent of these patients were treated in the first-line, with a median PFS of 9.7 months (95% CI 6.6-17.1) and median OS of 21.3 months (95% CI 14.6-36.5). Elevated LDH levels and the presence of BRAF mutation were significantly associated with lower OS. No significant association was found between acral subtype and PFS, or OS after adjustment for covariates. Conclusions: This study shows limited efficacy of anti-PD1 for advanced AM, with clinically relevant lower response rates compared to nonacral melanoma types. Although caution is needed because of relatively small numbers and the observational nature of our study, our data confirm limited efficacy of checkpoint inhibition in AM.

BRAF and NRAS mutation status and response to checkpoint inhibition in advanced melanoma

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Background: The ability to analyze tumor mutation profiles has altered the oncology treatment landscape over the past decades. However, little is known about the effect of specific gene mutations on the response to immune checkpoint inhibitors (ICIs) in patients with advanced melanoma. Methods: All unresectable stage IIIc and IV patients with BRAF V600, NRAS mutations and BRAF and NRAS wild-type patients treated with anti-PD-1 or ipilimumab-nivolumab between 2012 and 2020 were included from the Dutch Melanoma Treatment Registry, a nationwide population-based registry. Outcomes were objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). A Cox model was used to analyze the association of possible prognostic factors with PFS and OS. Results: In total 1358 first-line patients treated with anti-PD-1 and 524 treated with ipilimumab-nivolumab were included. Median follow-up was 25.6 months for anti-PD-1 treated patients and 16.3 months for ipilimumab-nivolumab treated patients. The highest ORR, in first-line, to anti-PD-1 was in patients who were BRAF and NRAS wildtype (50.2%), compared to BRAF V600 (43.8%) and NRAS mutated patients (49.8%). ORR to ipilimumab-nivolumab was highest in NRAS mutated patients (44.9%), while ORR was 39.5% for BRAF mutated patients and 40.3% for wild-type patients. Median PFS in the anti-PD-1 treatment regimen was significantly higher (p = 0.049) for double wild-type patients (16.7 months) patients than for BRAF mutated patients (9.9 months) and NRAS mutated patients (11.3 months). PFS was not significantly different (p = 0.11) in the ipilimumab-nivolumab treatment cohort, with a median PFS of 6.5 months for the wild-type group, 10.8 months for the BRAF group, and 9.1 months for the NRAS group. In the anti-PD-1 treated patients, median OS was significantly higher (p < 0.001) for BRAF mutated patients (32.8 months) compared to NRAS (21.0 months) and wild-type patients (23.0 months). For ipilimumab-nivolumab treated patients, median OS was also significantly higher (p < 0.001) for BRAF mutated patients (36.5 months) than for NRAS mutated patients (11.8 months) and wild-type patients (16.1 months). After adjustment for potential confounders, the presence of a BRAF mutation remained associated with lower PFS in the anti-PD-1 treatment cohort and better OS in both treatment cohorts. Higher age, higher ECOG score, elevated LDH levels, liver metastases and brain metastases were associated with worse survival. Conclusions: PFS in first-line PD-1 was significantly higher for double wild-type patients than for BRAF mutant and NRAS mutant patients. PFS in ipilimumab-nivolumab treated patients did not significantly differ between BRAF mutant, NRAS mutant and double wild-type patients. OS was significantly higher for BRAF mutant patients in both treatment strata, which is probably the result of the subsequent BRAF/MEK-inhibition treatment option in this group.

Dutch advanced melanoma care in times of COVID-19

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Background: The COVID-19 pandemic COVID had a severe impact on medical care in The Netherlands. So far, few studies have investigated the influence of COVID-19 on advanced melanoma care nationwide. This study aims to investigate the impact of COVID-19 on the systemic treatment of unresectable stage III and IV advanced melanoma patients in the Netherlands. Methods: Data were obtained from the Dutch Melanoma Treatment Registry (DMTR), a population-based nationwide registry of all stage III and IV melanoma patients amenable for systemic treatment. We compared two patient groups dependent on the date of the first diagnosis of metastasis: during the first COVID-19 wave (March 15th 2020 until May 22nd 2020), and a control group during the same period one year earlier. Furthermore, we divided patients into three geographical regions within the Netherlands (north, middle and south). These regions were based on the maximum number of hospital admissions for COVID-19 patients during the first wave, using data from the National Intensive Care Evaluation (NICE). COVID-19 incidence was highest in the southern part of The Netherlands. We investigated baseline characteristics, type of systemic therapy, time from diagnosis of the irresectable stage III or IV melanoma until the start of systemic therapy, postponement of anti-PD-1 courses in patients actively being treated during the predefined time periods and progression-free survival (PFS) and overall survival (OS) using Kaplan-Meier estimates. Results: During the first COVID-19 wave, 104 patients were diagnosed with advanced melanoma versus 166 patients during the control period in 2019. No significant differences were found in patient and tumor characteristics, type of systemic therapies or in the time from diagnosis until the start of systemic therapy, between the different periods. However, during the first wave, the time between diagnosis until the start of treatment was significantly longer in the southern regions as compared to the northern and middle regions (33 vs 9 and 15 days, p-value < 0.05). Anti-PD-1 antibody treatment courses were postponed in 79 patients (15.5%) during the first wave versus four patients (1.1%) in the control period. Significantly more patients had a postponed course in the south during the first wave compared to the middle and northern regions (30.2% vs 2.7% vs 16.7%, p-value < 0.001). With limited follow-up, thus far no significant differences in PFS and OS were found. Conclusions: Advanced melanoma care in the Netherlands was severely affected by the COVID-19 pandemic. In the south, where COVID-19 incidence was highest in the first wave, the start of systemic treatment for advanced melanoma was more often delayed, and treatment courses were more frequently postponed. Longer follow-up is needed to establish whether this has had an impact on patient outcome.

ESP, EORTC, and EURACAN Expert Opinion: practical recommendations for the pathological diagnosis and clinical management of intermediate melanocytic tumors and rare related melanoma variants

The recent WHO classification of skin tumors has underscored the importance of acknowledging intermediate grade melanocytic proliferations. A multistep acquisition of oncogenic events drives the progressive transformation of nevi into melanomas. The various pathways described are modulated by the initial oncogenic drivers that define the common, blue, and Spitz nevi groups. Intermediate lesions are most often the result of a clonal evolution within such nevi. Based on this established classification, we have suggested for each pathway a practical diagnostic approach, benefiting from the recently developed molecular tools, both in the setting of general pathology labs and expert centers. Moreover, recommendations regarding the re-excision and clinical follow-up are given to support decision-making in multidisciplinary tumor boards.

SOX10 is as specific as S100 protein in detecting metastases of melanoma in lymph nodes and is recommended for sentinel lymph node assessment

BACKGROUND

Sentinel lymph node (SLN) biopsy remains crucial for melanoma staging. The European Organisation for Research and Treatment of Cancer Melanoma Group recommends performing immunohistochemical stainings for reproducible identification of melanoma metastases. S100 protein (pS100) is a commonly used melanocytic antigen because of its high sensitivity in spite of relatively low specificity. SRY-related HMG-box 10 protein (SOX10) is a transcription factor characterising neural crest-derived cells. It is uniformly expressed mostly in the nuclei of melanocytes, neural, and myoepithelial cells. Pathologists sometimes prefer SOX10 as a melanoma marker, but it has not yet been investigated on a large-scale to confirm that it is reliable and recommendable for routine SLN evaluation.

METHODS

Four hundred one treatment-naïve lymph node (LN) metastatic melanomas were included in high-density tissue microarrays and were assessed for the presence of SOX10 and pS100 by immunohistochemistry. The slides were digitalised, shared and evaluated by a panel of experienced melanoma pathologists.

RESULTS

The vast majority of melanomas were double-positive for pS100 and SOX10 (93.2%); a small percentage of the cases (3.9%) were double-negative melanomas. Discordance between the two markers was observed: 1.9% pS100(-)/SOX10(+) and 0.75% pS100(+)/SOX10(-). SOX10 was not expressed by immune cell types in the LN, resulting in a less controversial interpretation of the staining.

CONCLUSIONS

SOX10 is as equally specific as pS100 for the detection of melanoma metastases in LNs. The interpretation of SOX10 staining is highly reproducible among different centres and different pathologists because of the absence of staining of immune cells.

In situ expression of tumor antigens by messenger RNA-electroporated dendritic cells in lymph nodes of melanoma patients

Electroporation of dendritic cells (DC) with mRNA encoding tumor-associated antigens (TAA) for cancer immunotherapy has been proved efficient and clinically safe. It obviates prior knowledge of CTL and Th epitopes in the antigen and leads to the presentation of multiple epitopes for several HLA alleles. Here we studied the migration capacity and the antigen expression of mRNA-electroporated DC (mRNA-DC) in lymph nodes after vaccination in melanoma patients. DC were electroporated with mRNA encoding gp100 or tyrosinase, labeled with indium-111 and superparamagnetic iron oxide particles, and injected intranodally in melanoma patients 24 to 48 hours before scheduled dissection of regional lymph nodes. Immunohistochemical analysis of the lymph nodes after surgery revealed that mRNA-DC migrated from the injection site into the T-cell areas of the same and subsequent lymph nodes, where they expressed the antigen encoded by the electroporated mRNA. Furthermore, vaccine-related CD8(+) T-cell responses could be detected in 7 of 11 patients vaccinated with mRNA-DC. Together these data show that mature DC electroporated with mRNA encoding TAA migrate and express antigens in the lymph nodes and induce specific immune responses.

Immunohistochemical features of cutaneous granulomas in primary immunodeficiency disorders: a comparison with cutaneous sarcoidosis

BACKGROUND

Cutaneous granulomas can occur in patients with a primary immunodeficiency disorder. In some cases, an infectious cause cannot be revealed. The pathogenesis of these granulomas still remains to be elucidated. The aim of this study was to study differences or overlap between these rare granulomas and sarcoidosis-related granulomas.

METHODS

Markers for T-cell subsets (CD3, CD4, CD8 and CD45RO), Langerhans' cells (CD1a), macrophages (CD68), B cells (CD20) and NK cells (CD56) were stained immunohistochemically. The amount of CD4+ and CD8+ cells in the granulomas was counted. Results were compared with the CD4+/CD8+ ratio in peripheral blood.

RESULTS

In the granulomas of two of three patients with a primary immunodeficiency disorder, the cytotoxic T cells (CD8+) outnumbered the T-helper cells (CD4+) with a counted CD4+/CD8+ ratio <<1. In contrast, the granulomas in the cutaneous sarcoidosis patients showed a predominance of CD4+ cells, with CD4+/CD8+ ratios >2.

CONCLUSIONS

A lower CD4+/CD8+ ratio was found in the cutaneous granulomas of patients with a primary immunodeficiency disorder (unclassified combined immunodeficiency, autoimmune lymphoproliferative syndrome and ataxia teleangiectasia) as compared with the patients with cutaneous sarcoidosis. The possible implications of these findings are discussed in this paper.

High expression levels of keratinocyte antimicrobial proteins in psoriasis compared with atopic dermatitis

Recently, it was shown that lesional skin of atopic dermatitis patients expresses low levels of some antimicrobial peptides, compared with psoriasis patients. Here we performed microarray analysis on mRNA from purified lesional epidermal cells of patients with chronic plaque psoriasis and chronic atopic dermatitis, to investigate whether this is a general phenomenon for host defense proteins, and how specific it is for this class of molecules. Microarray data were confirmed on a selected set of genes by quantitative PCR and at the protein level by immunohistochemistry. We found overexpression of many antimicrobial proteins in keratinocytes from psoriatic skin compared with atopic dermatitis skin. Interestingly, we observed that markers of normal differentiation and the activated/hyperproliferative epidermal phenotype were expressed at equal levels. Chronic lesions of psoriasis and atopic dermatitis patients are remarkably similar with respect to cellular proliferation. We conclude that psoriatic epidermis expresses high levels of host defense proteins compared with atopic dermatitis epidermis, and this phenomenon appears to be specific for these proteins. It remains to be investigated whether this is caused by genetic polymorphisms in pathways leading to an epidermal antimicrobial response, or by differences in the cellular infiltrate in psoriasis compared with atopic dermatitis.