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Abstract: Mycosis fungoides (MF) has become one of the most difficult diagnostic challenges for both dermatologists and dermatopathologists because its clinical presentation and microscopic findings may mimic benign reactive processes, specifically those displaying histopathological features of interface dermatitis. The goal of our study was to prove with digital scanning and automated sample methodology through algorithmic analysis, combined with the utility of TOX marker a more precise, faster, and objective evaluation of each sample. Moreover, this would offer high levels of reproducibility with the possibility of establishing cut-off points, allowing us to distinguish between inflammatory dermatoses (ID) and MF. A retrospective longitudinal-descriptive and observational study was conducted to compare the diagnostic criteria (immunohistochemical studies of anti-TOX stain) in patients with clinical suspicion of MF by dividing them into 2 groups: samples with a positive biopsy for MF (MF group) and those with a negative biopsy, therefore diagnosed as an ID (control group). The algorithm assessed 5 selected areas with lymphocytic representative cellularity, and based on the intensity, nuclear staining was classified as 0 (negative), 1+ (weak/yellow), 2+ (moderate/orange), and 3+ (strong/scarlet red) nuclei. The results showed statistically significant differences ( P = 0.040) between the mean number of (2+) nuclei in the positive final diagnosis group (MF group) and the negative final diagnosis group (ID group)., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: Melanocytic matricoma with atypical features is a rare, biphasic adnexal neoplasm displaying hair matrix differentiation, with only 3 reported cases worldwide. Generally, the lesion comprised a solid matrical and supramatrical cell proliferation, admixed with intermediate cell aggregates with sparse anucleated "shadow cells" and a prominent pigmented melanocytic hyperplasia. We report the case of a 78-year-old man with a slow-growing crusted lesion on the frontal left scalp, which in a matter of 1-2 months became a 0.6 cm well-defined, black purplish exophytic nodule. Histopathologically, the lesion presented a well-circumscribed border with a nodular dermal growth pattern, presenting different architectural features varying from benign pilomatricoma-like changes to atypical features such as moderate-to-high nuclear pleomorphism in both basaloid (matrical/supramatrical) and epidermal (keratinous) components. Strong nuclear and cytoplasmic positivity for β-catenin was observed in matrical cells, whereas prominent cytoplasmic membrane positivity for Melan-A in dendritic melanocytes. Owing to the evidence of atypical cytological features, we propose the "atypical/borderline" category of melanocytic matricoma as part of a possible spectrum among matrical neoplasms. Pathologists should be aware of any atypical histopathological features while reporting cases due to their potential malignant transformation., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)