CD123 immunohistochemistry for plasmacytoid dendritic cells is useful in the diagnosis of scarring alopecia

Oral lupus erythematosus: Immunohistochemical evaluation of CD1a, CD21, CD123, and langerin expression in dendritic cells

BACKGROUND

Dendritic cells participate in the pathophysiology of lupus erythematosus (LE), which are studied in systemic and cutaneous forms; however, little is known about their oral manifestations.

METHODS

The expressions of dendritic cell markers (including CD1a, CD21, CD123, and langerin) were investigated by immunohistochemistry technique. Sixty intraoral and lower lip LE lesions, and additional 10 control samples were collected from 2003 to 2019. They were topographically analyzed in the epithelium (EP), lamina propria (LP), epithelial junction (JUN), and deep perivascular (PV) areas.

RESULTS

The expression of CD1a was decreased in the EP (p = 0.003) and increased in the deep PV area (p = 0.002). Langerin immunostaining showed no significant decrease in EP (p = 0.944); however, it increased in LP (p = 0.012) and JUN (p = 0.006). CD21 was expressed in only two specimens (EP, p = 0.012; LP, p < 0.001; deep PV area, p = 0.018). CD123 expression increased in all topographies (EP, p < 0.005; LP, p < 0.001, JUN, p < 0.001; deep PV, p < 0.001). The comparison between vermilion and intraoral mucosa LE lesions suggested that sun-exposed sites showed higher expression of CD123 (EP, p = 0.024; LP, p = 0.047; JUN, p = 0.001).

CONCLUSIONS

CD1a, langerin, and CD123 expressions were detected coincidently surrounding the inflammatory infiltrate in oral LE, suggesting that these cells may play an important role in immune response. Interestingly, plasmacytoid dendritic cells showed increased CD123 expression in sun-exposed site lesions, which point out a possible function in their pathogenesis. Further studies are needed to confirm this hypothesis.

The Spectrum of Cutaneous Manifestations in Lupus Erythematosus: A Comprehensive Review

Lupus erythematosus (LE) is an autoimmune inflammatory disease with complex etiology. LE may present as a systemic disorder affecting multiple organs or be limited solely to the skin. Cutaneous LE (CLE) manifests with a wide range of skin lesions divided into acute, subacute and chronic subtypes. Despite classic forms of CLE, such as malar rash or discoid LE, little-known variants may occur, for instance hypertrophic LE, chilblain LE and lupus panniculitis. There are also numerous non-specific manifestations including vascular abnormalities, alopecia, pigmentation and nail abnormalities or rheumatoid nodules. Particular cutaneous manifestations correlate with disease activity and thus have great diagnostic value. However, diversity of the clinical picture and resemblance to certain entities delay making an accurate diagnosis The aim of this review is to discuss the variety of cutaneous manifestations and indicate the clinical features of particular CLE types which facilitate differential diagnosis with other dermatoses. Although in diagnostically difficult cases histopathological examination plays a key role in the differential diagnosis of LE, quick and accurate diagnosis ensures adequate therapy implementation and high quality of life for patients. Cooperation between physicians of various specialties is therefore crucial in the management of patients with uncommon and photosensitive skin lesions.

Alopecias: Practical Tips for the Management of Biopsies and Main Diagnostic Clues for General Pathologists and Dermatopathologists

Accurately diagnosing specific variants of alopecia remains challenging for pathologists, potentially delaying appropriate therapeutic decisions by dermatologists. Issues such as limited knowledge on optimal biopsy types and processing methods add complexity. Understanding the normal histology of hair follicles and their changes throughout the follicular cycle further complicates microscopic evaluation. This paper aims to summarize these characteristics and highlight essential diagnostic clues for pathologists to confidently suggest a diagnosis, therefore playing a key role in alopecia diagnosis. Ongoing education, collaboration with dermatologists, and staying up to date on advancements is crucial for the accurate diagnosis and effective management of different types of alopecia.

Tight correlation of 5-hydroxymethylcytosine expression with the scarring damage of discoid lupus erythematosus

OBJECTIVE

Cutaneous lupus erythematosus (CLE) is a heterogenous skin disease. The two most common subtypes are discoid LE (DLE) characterized by scarring skin damage and acute CLE (ACLE) presenting with transiently reversible skin lesions. It remains unknown what causes the difference of skin lesions. Studies have shown the existence of tissue-specific 5-Hydroxymethylcytosine (5 hmC)-modified regions in human tissues, which may affect the tissue-related diseases. Here, we aim to assess the expression of 5 hmc in DLE and ACLE lesions and explore the relationship of 5 hmc with scarring damage in DLE.

METHODS

84 CLE samples were included in the study. We evaluated the skin damage score and reviewed the histopathologic sections. Immunohistochemical staining was performed to detect the expression of 5 hmc in the appendage and periappendageal inflammatory cells. The 5 hmc expression in periappendageal lymphocytic cells was investigated by multi-spectrum immunohistochemistry staining.

RESULTS

Scarring/atrophy was the most significant damage in differentiating the DLE from ACLE. Perifollicular inflammatory infiltration was present in all patients with DLE scarring alopecia (DLESA). The 5 hmc expression in the appendage and periappendageal inflammatory cells was significantxly increased in DLESA than ACLE. Similar expression pattern was seen in the staining of IFN-alpha/beta Receptor (IFNAR). The expression of 5 hmc in the appendage was positively correlated with that in the periappendageal inflammatory cells. There was an increased 5 hmc expression in lymphocytes cluster around hair follicle consisting of CD4⁺ cells, CD8⁺ cells, and CD19⁺ cells in DLESA lesions.

CONCLUSION

These data demonstrate a close association of the expression pattern of 5 hmc with the histopathological characteristic distribution, and with the type I interferons (IFNs) signals in DLESA, supporting the importance of 5 hmc in the amplification of appendage damage and periappendageal inflammation, thereby offering a novel insight into the scarring damage of DLE and the heterogeneity of CLE skin lesions.

Plasmacytoid Dendritic Cell marker (CD123) expression in scarring and non-scarring alopecia

Classification of scarring alopecia poses a major problem, as there is considerable clinicopathologic overlap, particularly between lupus erythematosus (LE) and lichen planopilaris (LPP), especially in later stages. CD123 positive plasmacytoid dendritic cells (PDC) have been shown recently to be present in all forms of LE and are touted to be useful in differentiating LE from other scarring alopecias. Their distribution in non-scarring alopecia is not well documented. This is the first study that examines the PDC in both scarring and non-scarring alopecias.

Comparative Analyses of Clinical Features, Histopathology, and CD123 Immunohistochemistry of Oral Lupus Erythematosus, Lichen Planus, and Other Lichenoid Lesions

BACKGROUND

Oral lupus erythematosus (OLE) and oral lichen planus (OLP) are among the common causes of oral lichenoid lesions (OLLs). The differential diagnosis among causes of OLLs, particularly between OLE and OLP, is challenging as they have significant clinical and histopathological overlap.

OBJECTIVES

To compare and summarize the clinical, histopathological, and direct immunofluorescence (DIF) findings between OLE, OLP, and other OLLs and to explore the diagnostic value of CD123 immunohistochemistry.

METHODS

A retrospective study on patients with OLE, OLP, and other OLLs was performed between January 2014 and December 2019. The baseline characteristics, the clinical, histopathological, and DIF features, as well as CD123 immunohistochemistry for plasmacytoid dendritic cells (PDCs) were statistically analyzed and compared between groups.

RESULTS

Of 70 patients, 12 had OLE, 39 had OLP, and 19 had other OLLs. Oral erosions/ulcers were the most common findings in all three groups. Red macules, telangiectases, and discoid plaques were more common in OLE patients, while OLP cases were typified by reticulated patches (p < 0.05). Additionally, white patches were found more often in other OLLs than in both OLE and OLP (p = 0.002). Histologically, mucosal atrophy, basal vacuolization, and perivascular infiltrate were observed in OLE, whereas OLP specimens possessed mucosal hyperplasia, hypergranulosis, and compact orthokeratosis (p < 0.05). Mucosal spongiosis was a histologic feature that favored other OLLs over OLE and OLP (p < 0.001). Data on DIF were nonspecific for all three conditions. For immunohistochemical staining, the median number of total CD123+ PDCs was observed to be higher in OLE than OLP in the mucosal-submucosal junction (MSJ) (p = 0.021), the superficial perivascular area (p = 0.026), and the superficial and deep perivascular areas (p = 0.001). Likewise, PDCs in clusters ≥2+ were seen in significantly higher numbers on OLE than OLP along the MSJ (p = 0.002), the superficial perivascular area (p < 0.001), as well as the superficial and deep perivascular areas (p = 0.011). CD123+ PDCs were found to be significantly more numerous in both OLE and OLP than other OLLs in all of the abovementioned areas (all p < 0.05).

CONCLUSION

While there are some differences in the clinicopathological features between OLE, OLP, as well as other OLLs, a significant overlap remains. The quantity and distribution pattern of CD123 immunohistochemical staining has a diagnostic implication in differentiating OLE from OLP and other OLLs.

Diagnostic utility of plasmacytoid dendritic cells in dermatopathology

Differentiating cutaneous diseases that mimic each other clinically and histopathologically can at times be a challenging task for the dermatopathologist. At the same time, differentiation of entities with overlapping features may be crucial for patient management. Although not seen in normal skin, plasmacytoid dendritic cells usually infiltrate the skin in several infectious, inflammatory/autoimmune and neoplastic entities. Plasmacytoid dendritic cells can be identified in tissue using specific markers such as CD123 and/or blood-derived dendritic cell antigen-2. Plasmacytoid dendritic cells are the most potent producers of type I interferons and their activity may therefore be assessed indirectly in tissue using human myxovirus resistance protein A, a surrogate marker for type I interferon production. In recent years, accumulating evidence has established the utility of evaluating for specific plasmacytoid dendritic cell-related parameters (plasmacytoid dendritic cell content, distribution and clustering and/ or human myxovirus resistance protein A expression) as a diagnostic tool in differentiating cutaneous diseases with overlapping features such as the alopecias, lupus and its mimics, and neoplastic entities. In this review, we provide an update on the current evidence on this topic and on the contexts where this can be a useful adjunct to reach the histopathological diagnosis.

Lichen planus follicularis tumidus: Immunotyping of the inflammatory infiltrate with focus on plasmacytoid dendritic cells

Lichen planus follicularis tumidus (LPFT) is a rare clinicopathological variant of lichen planus (LP), clinically presenting with red-to-violaceous plaques studded with comedo-like lesions and keratin-filled milia-like cysts. Histopathologically, LPFT is characterized by cystically dilated follicular infundibula in the dermis, surrounded by a dense lichenoid lymphoid infiltrate with an associated interface reaction. We describe the clinicopathological features of an additional case of LPFT, focusing on the number and distribution of CD123(+) TCF4(+) plasmacytoid dendritic cells (pDCs). In our case, pDCs represented approximately 5% of the total inflammatory infiltrate, predominantly exhibiting a lichenoid distribution around the infundibula with no evidence of cluster formation, thus ruling out cutaneous lupus erythematosus. Our report is the first to describe the number and distribution of pDCs in LPFT. The results of our immunohistochemical analysis corroborate the notion that LPFT should be regarded as a rare variant of LP.

Value of CD123 Immunohistochemistry and Elastic Staining in Differentiating Discoid Lupus Erythematosus from Lichen Planopilaris

Background:

Differentiating scarring alopecia secondary to lichen planopilaris (LPP) and discoid lupus erythematosus (DLE) has always been a challenge clinically and pathologically. Plasmacytoid dendritic cells (PDCs) have been reported in the cutaneous lupus erythematosus by CD123 immunostaining. This study assesses CD123 marker positivity and patterns of elastic fiber loss in scalp biopsy to differentiate DLE from LLP.

Patients and Methods:

Forty-three cases with clinical and pathological diagnosis of LPP and DLE were selected, and CD123 immunohistochemistry staining and elastic staining were performed on them. The presence of CD123-positive cells, clustering and distribution of cells, and patterns of elastic fibers loss in the dermis were evaluated. To analyze the data, the Chi-square test was used; moreover, the sensitivity and specificity of CD123 were calculated based on a diagnostic test for 2-by-2 tables.

Results:

Infiltration of PDC was seen in 90% of DLE cases. The presence of more than 10% and 20% PDC cells in inflammatory cells had 90% and 85% sensitivity and 34.7% and 91.3% specificity, respectively. PDC clusters more than 20 cells had 100% specificity for DLE. Location and patterns of PDC infiltration were not statistically significant (P = 0.378). The wedge-shaped loss of elastic fibers and the diffuse loss were the dominant patterns in LPP and DLE, respectively (P = 0.006).

Conclusion:

Our results suggested that CD123 along with elastic staining and histological features might be useful to diagnose challenging cases of lymphocytic scarring alopecia with clinical differential diagnosis of LPP and DLE.

Different distribution patterns of plasmacytoid dendritic cells in discoid lupus erythematosus and lichen planopilaris demonstrated by CD123 immunostaining

Background

Clinical and histological features may overlap between lichen planopilaris-associated and discoid lupus erythematosus-associated scarring alopecia.

Objectives

The aim of this study was to demonstrate the cutaneous infiltration of plasmacytoid dendritic cells and to compare their distribution pattern in discoid lupus erythematosus and lichen planopilaris.

Methods

Twenty-four cases of discoid lupus erythematosus and 30 cases of lichen planopilaris were examined for immunostaining of the CD123 marker. The percentage and distribution pattern of plasmacytoid dendritic cells and the presence of the plasmacytoid dendritic cells clusters were evaluted in the samples.

Results

The number of plasmacytoid dendritic cells was higher in the discoid lupus erythematosus specimens. Aggregations of 10 cells or more (large cluster) were observed in half of the discoid lupus erythematosus specimens and only 2 lichen planopilaris, with 50% sensitivity and 93% specificity for differentiating discoid lupus erythematosus from lichen planopilaris.

Study limitations

Incidence and prevalence of discoid lupus erythematosus-associated scarring alopecia in the scalp are low, so the samples size of our study was small.

Conclusions

We suggest that a plasmacytoid dendritic cells cluster of 10 cells or more is highly specific for distinguishing discoid lupus erythematosus from lichen planopilaris. It also appears that CD123 immunolabeling is valuable in both active and late stages of the disease.

Clinicopathologic and immunophenotypic characterization of lichen planopilaris and central centrifugal cicatricial alopecia: A comparative study of 51 cases

BACKGROUND

The purpose of the study was to compare the histopathologic and immunophenotypic features of central centrifugal cicatricial alopecia (CCCA) and lichen planopilaris (LPP) to better characterize and differentiate these two clinical entities. CCCA remains an ill-defined and still-unsettled histologic entity and many hair loss experts regard CCCA to be histologically indistinguishable from LPP. Given the overlapping histologic features of these two lymphocyte-predominant cicatricial alopecias, and the lack of consensus regarding the significance of proposed distinctions, dermatopathologists face difficulty in providing clinicians and patients certainty with a definitive diagnosis of CCCA vs LPP.

METHODS

We performed a retrospective review of 51 scalp biopsies of patients with either the clinical diagnosis of CCCA (27 cases) or LPP (24 cases). Clinical information, histologic features of hematoxylin-eosin-stained sections, and a panel of immunohistochemical markers were evaluated on scalp biopsies. Tested parameters were quantified, and statistical analysis was performed.

RESULTS

Our study found no differences on either histologic assessment or immunophenotypic characterization between cases of classic LPP and CCCA.

CONCLUSION

The conclusion of this study is that the inflammatory infiltrates in CCCA and LPP are not only histologically similar but also immunophenotypically indistinguishable.

Plasmacytoid dendritic cells in keratoacanthoma and squamous cell carcinoma: A blinded study of CD123 as a diagnostic marker

BACKGROUND

Histopathologic distinction between keratoacanthoma (KA) and squamous cell carcinoma (SCC) is challenging. We surmised that a discriminatory immunostain would be clinically meaningful. Previous investigators have found CD123-positive plasmacytoid dendritic cells (PDCs) are more prominent in KA than SCC. We sought to determine if CD123 immunostaining might have value as a diagnostic test for distinguishing KA from SCC.

METHODS

We used blinded, semi-automated image analysis to compare CD123 expression in 66 KAs and 63 SCCs in a tissue microarray.

RESULTS

PDCs were present in both KA and SCC. Mean PDC frequency was higher in KA than SCC (14.2 vs 11.2 mean cells/0.0945 square mm) but the difference was not statistically significant (P = 0.1240). There was no significant difference in mean PDC cluster frequency, mean intratumoral PDC frequency, or the percentage of PDCs as proportion of the total mononuclear inflammatory cell infiltrate between KA and SCC.

CONCLUSION

CD123 immunostaining is not a clinically useful test for distinguishing KA from SCC.

Genetic and Environmental Determinants of Immune Response to Cutaneous Melanoma

The immune response to melanoma improves the survival in untreated patients and predicts the response to immune checkpoint blockade. Here, we report genetic and environmental predictors of the immune response in a large primary cutaneous melanoma cohort. Bioinformatic analysis of 703 tumor transcriptomes was used to infer immune cell infiltration and to categorize tumors into immune subgroups, which were then investigated for association with biological pathways, clinicopathologic factors, and copy number alterations. Three subgroups, with "low", "intermediate", and "high" immune signals, were identified in primary tumors and replicated in metastatic tumors. Genes in the low subgroup were enriched for cell-cycle and metabolic pathways, whereas genes in the high subgroup were enriched for IFN and NF-κB signaling. We identified high MYC expression partially driven by amplification, HLA-B downregulation, and deletion of IFNγ and NF-κB pathway genes as the regulators of immune suppression. Furthermore, we showed that cigarette smoking, a globally detrimental environmental factor, modulates immunity, reducing the survival primarily in patients with a strong immune response. Together, these analyses identify a set of factors that can be easily assessed that may serve as predictors of response to immunotherapy in patients with melanoma. SIGNIFICANCE: These findings identify novel genetic and environmental modulators of the immune response against primary cutaneous melanoma and predict their impact on patient survival.See related commentary by Anichini, p. 2457.