Journal of Cutaneous Pathology最新文献

Background: Distinguishing hand eczema from palmar psoriasis is a common diagnostic challenge due to overlapping clinical and histopathological features.

Objective: This study aimed to validate morphological and immunohistochemical criteria for differentiating these two conditions using the digital pathology tools QuPath and ImageJ.

Methods: One hundred forty-two histological samples with confirmed clinical diagnoses were stained with hematoxylin and eosin and subjected to immunohistochemical staining for CD3, CD15, CD20, CD123, S100, and PHH3. The samples were digitized for analysis. QuPath was used to automate annotation, segment epidermal layers, and measure rete ridge elongation, width, and suprapapillary epidermal thickness. Immunohistochemical markers were also analyzed using QuPath. ImageJ was employed to quantify spongiosis using color thresholding techniques.

Results: Suprapapillary epidermal thickness was significantly lower in psoriasis compared to eczema (p < 0.001; AUC = 0.72). Rete ridge elongation (p = 0.002; AUC = 0.704) and width (p < 0.001; AUC = 0.698) also showed significant differences. Furthermore, hypogranulosis was more pronounced in psoriasis (p = 0.012; AUC = 0.602), while S100-positive cells in the epidermis were more commonly observed in eczema (p = 0.013; AUC = 0.583).

Conclusion: Quantitative assessment of suprapapillary epidermal thickness and rete ridge morphology offers a reliable and objective method for differentiating palmar psoriasis from hand eczema, enhancing diagnostic accuracy.

Infantile congenital melanocytic nevus (CMN) is a rare type of benign skin lesion originating from neural crest cells. A proliferative nodule (PN) may develop within CMN, and in some cases, atypical proliferative nodules (APNs) with distinct histopathological features may arise, complicating clinical diagnosis and management. This report describes a case of a giant infantile CMN with APN and novel genetic findings, including TPR::NTRK1 gene fusion and MCL1 amplification. An 8-day-old male presented with a large, uniform, hairless black lesion on the plantar skin. Histological examination revealed nevomelanocytes arranged in a nest-like pattern within the epidermis and dermis. The PN displayed distinct boundaries, with spindle-shaped and oval cells exhibiting pleomorphism, and diffuse infiltration into the subcutaneous fascia and skeletal muscle. Immunohistochemical analysis demonstrated diffuse positivity for HMB45, Melan-A, and S-100 in nevus cells. In the PN, pan-TRK was positive, CD99 showed weak and focal expression, P16 was retained, and PRAME was negative. Genetic analysis revealed a TPR::NTRK1 gene fusion and MCL1 amplification, suggesting a molecular basis for the atypical features observed in the nodule. This case highlights the role of TPR::NTRK1 fusion in driving abnormal melanocyte proliferation and the potential contribution of MCL1 amplification to tumor progression. These findings provide insights into the genetic underpinnings of APN in CMN and suggest potential therapeutic targets for high-risk lesions.

Myoepithelioma-like tumor of the vulva region (MELTVR) is a low-grade mesenchymal neoplasm and mainly arises in the subcutaneous tissue of the vulva and surrounding regions in adult females. Here, a case of MELTVR is reported and the literature is systematically reviewed to shed light on this rare disease. The patient was a 46-year-old female who presented with a lump in the right vulva region after local trauma. On microscopic examination, the tumor cells displayed epithelioid or spindled morphology with fine amphophilic cytoplasm and uniform nuclei with vesicular chromatin. Immunohistochemical staining showed that tumor cells were positive for vimentin and calponin but negative for S100 protein, glial fibrillary acidic protein, AE1/AE3, and CD34. INI1/SMARCB1 expression was absent in the tumor nuclei. Fluorescence in situ hybridization revealed no EWSR1 or FUS gene rearrangements. These findings confirm the diagnosis of MELTVR. Although the biological behaviors of MELTVR remain incompletely understood, recognition of its characteristic morphologic and immunophenotypic profiles will aid in distinguishing it from potential histological mimics better.

Whipple's disease (WD) is a rare infectious disease caused by Tropheryma whipplei, which primarily affects the gastrointestinal tract but may also involve the joints, central nervous system, and skin. Although cutaneous manifestations are often overlooked, they can provide valuable diagnostic clues. We report the case of a 54-year-old male with long-standing seronegative migratory polyarthritis refractory to conventional treatment, who subsequently developed multiple subcutaneous inflammatory nodules and systemic symptoms. Histopathological examination of these lesions revealed a non-vasculitic, septal-predominant panniculitis with foamy macrophages containing periodic acid-Schiff (PAS)-positive diastase-resistant intracytoplasmic inclusions, raising a strong suspicion of Whipple's disease. Subsequent duodenal biopsies confirmed the diagnosis by electron microscopy and polymerase chain reaction (PCR) for T. whipplei. Panniculitis in WD represents a highly specific but rarely reported finding, characterized by thickened subcutaneous septa with partial lobular involvement, foamy macrophage infiltration, and absence of vasculitis. A literature review identified 15 cases of histologically confirmed WD-associated panniculitis, suggesting that this manifestation may be under-recognized in clinical practice. This study underscores the importance of cutaneous pathology in WD and expands current knowledge on its dermatological manifestations by providing clinicopathologic, ultrastructural, and literature-based data.

Primary cutaneous peripheral T-cell lymphoma with T-follicular helper phenotype (pcTFH-PTCL) is rare, and concurrent clonal B-lineage proliferations are uncommon. This lymphoma subtype presents unique diagnostic challenges due to its rarity and potential for misdiagnosis. We present a case of pcTFH-PTCL in an 88-year-old man with pruritic nodules on the shoulders, later developing multifocal cutaneous lesions including a prominent eyebrow nodule. Biopsies showed dense dermal infiltrates of CD4 positive T cells expressing TFH markers (PD-1, ICOS, and BCL6). Three lesions demonstrated an identical clonal T-cell receptor (TCR) gene rearrangement, confirming a clonal T-cell process. Remarkably, accompanying B-lineage components varied: lambda-restricted plasma cells and kappa-restricted B cells were identified in multiple lesions. Clonality studies revealed mostly distinct immunoglobulin heavy chain (IGH) rearrangements across separate sites, indicating independent B-cell clones. Whole exome sequencing revealed a pathogenic DNMT3A p.Arg882Cys mutation in two different biopsy sites. This case represents a rare pcTFH-PTCL with a persistent T-cell clone coexisting with divergent clonal B- and plasma cell populations. The findings emphasize the role of TFH-derived neoplasms in fostering B-cell expansions and highlight the diagnostic and therapeutic complexity posed by dual-lineage clonality in cutaneous lymphomas.

Synovial metaplasia was described in animal studies since the 1950s and was assumed to be a reaction to tissue disruption and theoretically related to the embryological formation of diarthrodial joints in utero. Since the description of the phenomenon in the cutaneous layer in a small case series in 1987, the prevalence has increased gradually with case reports and series published on many variations of its presentations and inciting events. We present a case of a hypertensive, otherwise physically fit 38-year-old female with a one-year history of coxalgia unresponsive to oral analgesia and discuss the possibility that the cutaneous metaplastic synovial cyst is an adaptive response to multiplanar shear forces and forms part of a spectrum of potential clinical presentations based on location.

Lorigerlimab is a dual bispecific antibody (BsAb) targeting cytotoxic T-lymphocyte-associated protein 4 and programmed cell death protein 1 that is used for treatment of advanced solid cancers such as metastatic castration-resistant prostate carcinoma. Reported cutaneous immune-related adverse events (irAEs) of lorigerlimab, such as pruritus and rash, are mostly manageable. However, to the best of our knowledge, the clinical histopathologic features of irAEs of the skin to dual immune checkpoint blockade with BsAbs have not been characterized. We report herein on lorigerlimab-associated lichenoid and vacuolar interface dermatitis in two patients with metastatic castration-resistant prostate adenocarcinoma. Case 1 had a violaceous, papular eruption and a lichenoid, perivascular histopathologic reaction pattern that responded well to temporary withholding of lorigerlimab and to corticosteroids. Case 2 presented with a more severe rash characterized by mixed clinical features of psoriasiform, eczematous, and morbilliform eruption and a histopathologic pattern of vacuolar interface changes with superficial perivascular lymphocytic infiltrate, scattered dyskeratotic keratinocytes, and focal acantholysis. The eruption was refractory to treatment, despite the patient withholding lorigerlimab, leading to complete discontinuation of lorigerlimab. This report highlights the importance of histopathologic evaluation in guiding treatment decisions for lorigerlimab-associated irAEs and underscores the need for further research into its dermatologic irAEs.

Background: Histopathologic features have been proposed as clues to potential dermatophyte infection. The inter-observer reproducibility and diagnostic accuracy of these features has not been rigorously studied.

Methods: Four blinded assessors at different levels of experience and training evaluated a cohort of 97 hematoxylin-eosin slides for 12 clues which might indicate dermatophytosis. Interobserver concordance, diagnostic accuracy metrics, and confidence intervals were calculated. Machine learning was used to develop predictive models. Model performance was compared with five-fold cross-validation.

Results: Interobserver agreement between two board-certified pathologists was moderate to substantial for most clues (nine predictors with kappa values of 0.40-0.64). In contrast, agreement was only slight for the sandwich sign and compact red corneum (kappa ≤ 0.05). Among all features, the presence of structures suspicious for dermatophytes was the only significant predictor of PAS positivity on multiple logistic regression (balanced accuracy = 0.88, p < 0.001). In machine learning models with 5-fold cross-validation, logistic regression using only the presence of suspected fungal hyphae as a predictor outperformed more complex approaches, including random forest, k-nearest neighbors, latent factor analysis, and support vector machines. Using penalized maximum likelihood, the estimated probability of a positive PAS result was 0.93 when possible hyphae were identified and 0.03 when they were not.

Conclusions: Possible fungal hyphae in the stratum corneum on H&E-stained sections is the most reliable histopathologic clue to dermatophytosis.