Major findings of the pilot study involving 21 critically ill patients during the week after admission to the critical care unit specialized for COVID-19 are presented. Fourteen patients have recovered, while seven passed away. There were no differences between them in respect to clinical or laboratory parameters monitored. However, protein adducts of the lipid peroxidation product 4-hydroxynonenal (HNE) were higher in the plasma of the deceased patients, while total antioxidant capacity was below the detection limit for the majority of sera samples in both groups. Moreover, levels of the HNE-protein adducts were constant in the plasma of the deceased patients, while in survivors, they have shown prominent and dynamic variations, suggesting that survivors had active oxidative stress response mechanisms reacting to COVID-19 aggression, which were not efficient in patients who died. Immunohistochemistry revealed the abundant presence of HNE-protein adducts in the lungs of deceased patients indicating that HNE is associated with the lethal outcome. It seems that HNE was spreading from the blood vessels more than being a consequence of pneumonia. Due to the limitations of the relatively small number of patients involved in this study, further research on HNE and antioxidants is needed. This might allow a better understanding of COVID-19 and options for utilizing antioxidants by personalized, integrative biomedicine approach to prevent the onset of HNE-mediated vitious circle of lipid peroxidation in patients with aggressive inflammatory diseases.

A recent comparison of clinical and inflammatory parameters, together with biomarkers of oxidative stress, in patients who died from aggressive COVID-19 and survivors suggested that the lipid peroxidation product 4-hydroxynonenal (4-HNE) might be detrimental in lethal SARS-CoV-2 infection. The current study further explores the involvement of inflammatory cells, systemic vascular stress, and 4-HNE in lethal COVID-19 using specific immunohistochemical analyses of the inflammatory cells within the vital organs obtained by autopsy of nine patients who died from aggressive SAR-CoV-2 infection. Besides 4-HNE, myeloperoxidase (MPO) and mitochondrial superoxide dismutase (SOD2) were analyzed alongside standard leukocyte biomarkers (CDs). All the immunohistochemical slides were simultaneously prepared for each analyzed biomarker. The results revealed abundant 4-HNE in the vital organs, but the primary origin of 4-HNE was sepsis-like vascular stress, not an oxidative burst of the inflammatory cells. In particular, inflammatory cells were often negative for 4-HNE, while blood vessels were always very strongly immunopositive, as was edematous tissue even in the absence of inflammatory cells. The most affected organs were the lungs with diffuse alveolar damage and the brain with edema and reactive astrocytes, whereas despite acute tubular necrosis, 4-HNE was not abundant in the kidneys, which had prominent SOD2. Although SOD2 in most cases gave strong immunohistochemical positivity similar to 4-HNE, unlike 4-HNE, it was always limited to the cells, as was MPO. Due to their differential expressions in blood vessels, inflammatory cells, and the kidneys, we think that SOD2 could, together with 4-HNE, be a potential link between a malfunctioning immune system, oxidative stress, and vascular stress in lethal COVID-19.

Background: Primary synovial chondromatosis (PSC) is a progressive disorder of unknown etiology resulting in formation of multiple loose bodies. If left untreated, it may lead to degenerative changes or malignant transformation to chondrosarcoma. Methods: Seventeen patients who underwent combined posterior and anterior ankle arthroscopy within the same operative session and had histologically confirmed PSC were included in this retrospective study. American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot score was used to evaluate ankle function preoperatively and at a final follow-up. A 3-question survey was used to evaluate patient’s satisfaction at the final follow-up. Results: In 14 patients, loose bodies were found in both compartments of the ankle, in 2 only in the anterior compartment, and in 1 only in the posterior compartment. All patients had evident signs of synovial inflammation in both compartments. The AOFAS Ankle-Hindfoot score increased from the preoperative median score of 65 (range, 29-90) to 95 (range, 65-100) at the final follow-up. Fourteen patients reported they were extremely satisfied with the outcome, 1 was moderately satisfied, and 2 were dissatisfied. No cases of recurrence of synovitis or loose body formation were noted, nor any signs of malignant transformation during the follow-up period. Conclusion: We believe the risk of recurrence of PSC, which is in close relation to malignant transformation, can be minimized by performing a complete synovectomy of the ankle. Our experience and review of literature makes us believe that ankle PSC should be regarded as a whole joint disorder. Performing a combined posterior and anterior arthroscopic procedure within the same operative session should always be considered in patients with ankle PSC. Level of Evidence: Level IV, retrospective case series.

We present an extremely rare and diagnostically challenging case of benign nodular smooth muscle proliferation (NSMP) in the lungs. A 41-year-old female patient presented with a cough and a right upper lung lobe lesion. Multislice computed tomography and positron emission tomography/computed tomography suggested malignancy despite relatively low metabolic activity. Fiberoptic bronchoscopy and transthoracic needle biopsy were inconclusive, so a right upper lobectomy with mediastinal lymphadenectomy was performed. Histopathology unveiled benign NSMP. This case underscores the diagnostic challenges of rare benign lung lesions mimicking malignancy and emphasizes a structured diagnostic and therapeutic approach. Clinical suspicion may arise in patients such as older adults presenting with well-defined pulmonary nodules, an inconclusive biopsy demonstrating smooth muscle proliferation, and low to moderate fluorodeoxyglucose uptake on positron emission tomography/computed tomography. When other diagnostic methods fail to provide a definitive diagnosis, surgical resection should be considered both as a diagnostic and therapeutic option. Histopathology remains the gold standard for differentiating benign from malignant lung lesions and enables definitive treatment in benign conditions, such as benign NSMP.