The aim of this study was to determine whether and how pan-CD44 protein expression in leukoplakia tissues correlates with positive SolCD44 test presence and their role in oral leukoplakia. SolCD44 and total protein expression in saliva were determined using an OncAlert^® Oral Cancer Rapid test. Comparison of paired associations of total protein, SolCD44, mean number of CD44 expressed epithelial layers in leukoplakia tissue, and macrophages below the basement membrane between control group and patients with leukoplakia showed statistically significant results (p < 0.0001). It is shown that the total protein indicates low or elevated risk of possible malignant transformation processes in leukoplakia. Statistically significant differences between higher total protein level and clinical forms of oral leukoplakia (p < 0.0001), as well as CD44-labeled epithelial cell layer decrease (p < 0.0001), were found. This possibly points to the onset of the stemness loss in leukoplakia tissue. CD9 antigen expression in the exosomes of the oral epithelium explained the intercellular flow of SolCD44 and other fluids in the leukoplakia area. We conclude that the OncAlert^® Oral Cancer Rapid test is a valuable screening method in daily clinical practice, in terms of complementing clinical diagnostics methods and to assess the potential for early malignancy.

Atypical teratoid/rhabdoid tumors (AT/RT) are highly aggressive tumors of the central nervous system (CNS), accounting for 1–3% of all pediatric CNS tumors. In general, AT/RTs are associated with biallelic inactivation of SMARCB1, resulting in the loss of expression of the integrase interactor 1 (INI1) protein. In this report, we describe the clinical course of an infant patient who presented with fatigue, postprandial vomiting, and disability of left side movement. Histological examination revealed classical features indicative of rhabdoid tumors, yet an atypical immunohistochemical profile with preserved INI1 expression was observed. Molecular diagnostics further elucidated the presence of a heterozygous frameshift variant, SMARCA4 c.2693del, p.(Asn898Thrfs*12), underscoring the distinctive genetic foundations of the case. Surgical resection of the tumor was administered with subsequent chemotherapy to the patient, but the condition worsened dynamically, and a decision was made to give the patient palliative therapy. We report on a patient with AT/RT caused by a rare mutation of the SMARCA4 gene and an aggressive course of disease to provide more information and characteristics of these tumors.