Cutaneous vasculitis: insights into pathogenesis and histopathological features.

The mechanisms underlying the onset and progression of vasculitis remain poorly understood. This condition is characterized by damage to the vascular wall, recruitment of inflammatory cells, and subsequent structural remodeling, which are hallmarks of vasculitis. The histopathological classification of vasculitis relies on the size of the affected vessel and the predominant type of inflammatory cell involved - neutrophils in acute cases, lymphocytes in chronic conditions, and histiocytes in granulomatous forms. Pathological changes progress in every context, and a single vasculitic pattern can be associated with various systemic conditions. Conversely, a single causative agent may lead to multiple distinct clinical and pathological manifestations of vasculitis. Moreover, many cases of vasculitis have no identifiable cause. A foundational understanding of the normal structure of the cutaneous vascular network is crucial. Similarly, identifying the cellular and molecular participants and their roles in forming the "dermal microvascular unit" is propedeutical.This review aims to elucidate the complex mechanisms involved in the initiation and progression of vasculitis, offering a comprehensive overview of its histopathological classification, underlying causes, and the significant role of the cutaneous vascular network and cellular dynamics. By integrating the latest insights from studies on NETosis and the implications of lymphocytic infiltration in autoimmune diseases, we seek to bridge gaps in current knowledge and highlight areas for future research. Our discussion extends to the clinical implications of vasculitis, emphasizing the importance of identifying etiological agents and understanding the diverse histopathological manifestations to improve diagnostic accuracy and treatment outcomes.

SATB2, CKAE1/AE3, and synaptophysin as a sensitive immunohistochemical panel for the detection of lymph node metastases of Merkel cell carcinoma.

Histopathological evaluation of lymph nodes in Merkel cell carcinoma has become crucial in progression estimation and treatment modification. This study was undertaken to determine the most sensitive immunohistochemical panel for detecting MCC nodal metastases. We included 56 patients with 102 metastatic MCC lymph nodes, which were tested with seven antibodies: cytokeratin (CKAE1/AE3), CK20, chromogranin A, synaptophysin, INSM1, SATB2, and neurofilament (NF). Tissue microarrays (TMA) composed of 2-mm tissue cores from each nodal metastasis were constructed. A semiquantitative 5-tier scoring system (0%, < 25%, 25-74%, 75-99%, 100% positive MCC cells with moderate to strong reactivity) was implemented. In the statistical assessment, we included Merkel cell polyomavirus (MCPyV) status and expression heterogeneity between lymph nodes from one patient. A cumulative percentage of moderate to strong expression ≥ 75% of tumoral cells was observed for single cell markers as follows: 91/102 (89.2%) SATB2, 85/102 (83%) CKAE1/AE3, 80/102 (78.4%) synaptophysin, 75/102 (75.5%) INSM1, 68/102 (66.7%) chromogranin A, 60/102 cases (58.8%) CK20, and 0/102 (0%) NF. Three markers presented a complete lack of immunoreactivity: 8/102 (7.8%) CK20, 7/102 (6.9%) chromogranin A, and 6/102 (5.9%) NF. All markers showed expression heterogeneity in lymph nodes from one patient; however, the most homogenous was INSM1. The probability of detecting nodal MCC metastases was the highest while using SATB2 as a first-line marker (89.2%) with subsequential adding CKAE1/AE3 (99%); these results were independent of MCPyV status. Synaptophysin showed a superior significance in confirming the neuroendocrine origin of metastatic cells. This comprehensive analysis allows us to recommend simultaneous evaluation of SATB2, CKAE1/AE3, and synaptophysin in the routine pathologic MCC lymph node protocol.

Decline of case reports in pathology and their renewal in the digital age: an analysis of publication trends over four decades.

AIMS: We investigated the trend in case reports (CRs) publication in a sample of pathology journals. Furthermore, we proposed an alternative publishing route through new digital communication platforms, represented by the 'social media case report'. METHODS: 28 pathology journals were selected from SCImago database and searched in PubMed to identify the number of published CRs. Four reference decades (1981-2020) were selected. The 5-year impact factor (IF) was retrieved from the Academic Accelerator database. RESULTS: CRs increased during the first three decades (6752, 8698 and 11148, respectively; mean values: 355, 27.3%; 334, 26.4%; 398, 28.8%) as the number of CR-publishing journals (19, 26 and 28, respectively). In the last decade, CRs significantly decreased (9341; mean 334, 23.6%) without variation in the number of CR-publishing journals (28). Half of the journals reduced CRs (from -1.1% to -37.9%; mean decreasing percentage -14.7%), especially if active since the first decade (11/14, 79%); the other half increased CRs (from +0.5% to +34.2%; mean increasing percentage +11.8%), with 8/14 (57%) starting publishing in the first decade. The 5-year IF ranged from 0.504 to 5.722. Most of the journals with IF ≥2 (10/14, 71%) reduced the CRs number, while 71% of journals with IF <2 increased CRs publication (especially journals with IF <1, +15.1%). CONCLUSIONS: CRs publication decreased during the last decade, especially for journals which are older or have higher IF. Social media CRs may represent a valid alternative and by using standardised templates to enter all relevant data may be organised in digital databases and/or transformed in traditional CRs.

Morphea Profunda with Tertiary Lymphoid Follicles: Description of Two Cases and Review of the Literature.

Morphea profunda or subcutaneous (deep) morphea is a variant of localized morphea, characterized by one or more ill-defined, deep sclerotic plaque. Preferential sites are the abdomen, trunk, sacral area, or extremities. The presence of hyperplastic lymphoid follicles in the context of the sclerotic bands of morphea is rarely described. Localized scleroderma is sustained by a profibrotic inflammatory profile. Transforming growth factor-ß (TGF-ß), an imbalance between functional subclasses of T-lymphocytes (innate immune cells) has a role in activate collagen deposition. In this case report, we present two cases of morphea profunda with lymphoid follicular hyperplasia. A systematic review of the literature on the pathophysiology of localized scleroderma is also presented, with particular reference to the presence of lymphoid structures.

Primary Cutaneous Follicle Center Lymphoma Clear Cell Variant: Expanding the Spectrum of Cutaneous Clear Cell Neoplasms.

Primary cutaneous follicle center lymphoma is the most frequent cutaneous B-cell lymphoma despite the fact that is an uncommon disease. Mild biological behavior and good prognosis characterized this neoplasm with a low aggressiveness compared with classic nodal follicular lymphoma (FL). Rare histological variants have been described. We present the case of a 72-year-old man who underwent surgery for a cutaneous nodule on his left scapula. The biopsy showed a dermal clear cell proliferation arranged in a nodular and diffuse pattern. The cells stained positive for CD20 and Bcl-6 supporting B-cell follicular differentiation. The final diagnosis was "primary cutaneous follicle center lymphoma" with "clear cell changes" according to the 2016 World Health Organization classification of lymphoid neoplasms. Additional tests to rule out a systemic involvement were performed. The prognosis was favorable with a disease-free survival of 7 years after complete surgical excision. It has been assumed that cutaneous tumors composed of clear cells may have an epithelial, melanocytic, adnexal, mesenchymal, or metastatic origin. The correct histopathological diagnosis required immunohistochemistry and even molecular techniques. To the best of our knowledge, this is the first report of a cutaneous clear cell lymphoma and of a FL with clear cell features. Our findings provide evidence that the heterogeneity of FL is greater than previously thought and expand the spectrum of differential diagnosis in cutaneous clear cell neoplasms. Dermatopathologists should be aware of this entity and should comprise a PanB marker in their first- or second-line immunohistochemistry for the correct diagnosis of a dermal clear cell proliferation.

Neutrophilic Dermatoses in Autoimmune Diseases: Report of Two Cases Associated with Autoimmune Thyroiditis.

The term "neutrophilic dermatoses" includes a rare inflammatory pattern characterized by neutrophil-rich cutaneous infiltrate. Both innate and adaptive immune pathways may be involved in neutrophil recruitment. Occasionally, neutrophilic dermatoses may occur in association with autoimmune thyroiditis. Pathogenetic aspects of this autoimmune disorder may elucidate their possible connection. Two exemplificative cases are taken as a pretext for a short review of this topic.