Background: The SARS-CoV-2 virus as well as the COVID-19 mRNA vaccines cause an increased production of proinflammatory cytokines. Aim: We investigated the relationship between ACE2, CTSL, AngII, TNFα and the serum levels of IL-6, IL-10, IL-33, IL-28A, CD40L, total IgM, IgG, IgA and absolute count of T- and B-lymphocytes in COVID-19 patients, vaccinees and healthy individuals. Methods: We measured the serum levels ACE2, AngII, CTSL, TNFα and humoral biomarkers (CD40L, IL-28A, IL-10, IL-33) by the ELISA method. Immunophenotyping of lymphocyte subpopulations was performed by flow cytometry. Total serum immunoglobulins were analyzed by the turbidimetry method. Results: The results established an increase in the total serum levels for ACE2, CTSL, AngII and TNFα by severely ill patients and vaccinated persons. The correlation analysis described a positive relationship between ACE2 and proinflammatory cytokines IL-33 (r = 0.539) and CD40L (r = 0.520), a positive relationship between AngII and CD40L (r = 0.504), as well as between AngII and IL-33 (r = 0.416), and a positive relationship between CTSL, total IgA (r = 0.437) and IL-28A (r = 0.592). Correlation analysis confirmed only two of the positive relationships between TNFα and IL-28A (r = 0.491) and CD40L (r = 0.458). Conclusions: In summary, the findings presented in this study unveil a complex web of interactions within the immune system in response to SARS-CoV-2 infection and vaccination.

Pemphigus is a group of autoimmune bullous diseases mediated by autoantibodies most often of the immunoglobulin G class, subclasses immunoglobulin G1, and immunoglobulin G4 (IgG4), directed against desmosomal adhesion proteins of keratinocytes. This study aimed to evaluate IgG4 immunoreactivity on paraffin sections using immunohistochemistry in patients with pemphigus as a diagnostic test. Fifty formalin-fixed paraffin-embedded specimens from patients with pemphigus were selected. Fifty formalin-fixed paraffin-embedded specimens from patients with bullous diseases other than pemphigus were used as controls. Biopsies were performed on active lesions in newly diagnosed patients. Immunohistochemistry for IgG4 was performed on paraffin sections with an anti-immunoglobulin G4 antibody. Positivity was defined as distinctive, uninterrupted immunoreactivity localized to the intercellular junctions of keratinocytes. A finding that did not meet these criteria was defined as negative. Forty-three (86.0%) of the examined patients had pemphigus vulgaris and 7 (14%) had pemphigus foliaceus. Forty-nine (98.0%) specimens from patients with pemphigus were immunoreactive for IgG4, 1 (2%) upper back biopsy from the patient with oral pemphigus showed negative immunoreactivity for IgG4. Negative immunoreactivity was found in 45 (90%) controls. Five (10%) controls with bullous pemphigoid showed immunoreactivity for IgG4. Sensitivity of the method was established to be 98% and specificity 90%. Immunohistochemical examination for IgG4 for the diagnosis of pemphigus can be applied when direct immunofluorescence examination is unavailable. The advantage of this method is that it does not require special equipment and the histology slides are permanent.

Analyzing the clinical and epidemiological data of COVID-19 suggests that specific comorbidities increase the risk of infection leading to worse lung injury and an even higher risk of death. The most common comorbidities reported up till now are hypertension, cardiovascular diseases, and diabetes. Aim to study: The design of the study includes comorbidity of patients and cause of death in alfa, delta, and omicron variants of SARS-CoV-2 virus, histological changes in the lungs, thrombotic complications of coronavirus infection and laboratory tests concerning thrombotic changes. Materials and Methods: We systematically evaluated 20 autopsies of patients deceased by COVID-19 infection. Collecting data was from February 28th, 2020, until June 2022. The cases were diagnosed with a PCR (Polymerase Chain Reaction) test and a rapid antigen test. 10 of the deceased patients were from the first, second, third, and fourth wave (I group) infected predominantly with the alfa and delta variants of coronavirus (from March 2020 until October 2021), and 10 patients infected after that date with predominantly the omicron variant (II group). Results: Most patients were over 50 years of age with multiple co-morbidities (28-88, average 63.9). Post-mortem case studies have shown Arterial hypertension in 80% (I/II gr), 60%/90% of patients with chronic ischemic heart disease, chronic and acute ischemic brain disease in 30%/10%, atherosclerosis, 60%/90%, diabetes mellitus 30%/40%, obesity stage III, 100%/95%). Clinical laboratory studies, in connection with thrombotic complications, revealed the increased value of creatine kinase, fibrinogen, D-dimers, and CRP. Lymphopenia was observed in 60%.All of the cases with COVID-19 viral desquamative pneumonia, at different stages, developed vascular thrombosis in medium-sized pulmonary vessels. Two patients developed pulmonary thromboembolism. We established 5 patients with generalized thrombosis. Three patients were complicated by infarcts in the brain, kidney, and spleen. Conclusion: The autopsies revealed a consistent pattern of pulmonary alveolar damage and generalized vascular/thrombotic disease in patients with frequent co-morbidities. The high frequency of generalized thrombotic complications was observed in predominant alfa and delta variants of the infection, while in the group with the omicron prevailing variant, the lung lesions were dominant, without extrapulmonary thrombotic complications, which we explain by the effective antithrombotic therapy. Major complications in these patients were secondary bacterial infection, sepsis, and respiratory distress syndrome.

There is only limited data on the prevalence of epidermal growth factor receptor (EGFR) activating mutations in squamous cell carcinomas and adenosquamous carcinomas of the lung in patients of the Southern Bulgarian region and the efficacy of EGFR tyrosine kinase inhibitors. AIM: Previous reports for Bulgarian population showed high incidence of EGFR mutations in the squamous cell carcinomas, so we set the goal to investigate their frequency in Southern Bulgaria, after precise immunohistochemical verification of lung cancers. MATERIALS AND METHODS: Two hundred and thirty-six lung carcinomas were included in this prospective study. All biopsies were initially analysed with p63, TTF1, Napsin A, CK7, CK34βE12, synaptophysin, CK20 and CDX2. Two hundred and twenty-five non-small cell lung carcinomas were studied with real-time PCR technology to assess the status of the EGFR gene. RESULTS: We detected 132 adenocarcinomas (58.7%), 89 squamous cell carcinomas (39.2%), 4 adenosquamous carcinomas (1.8%), 9 large cell neuroendocrine carcinomas (3.8%) and 2 metastatic colorectal adenocarcinomas (0.8%). Activating mutations in the EGF receptor had 3 out of 89 squamous cell carcinomas (3.37%). We have established mutations in L858R, deletion in exon 19 and rare mutation in S7681. One out of four adenosquamous carcinomas had a point mutation in the L858R (25%). CONCLUSIONS: The frequency of EGFR mutations we found in lung squamous cell carcinomas in a Southern Bulgarian region is lower than that in European countries. Ethnic diversity in the region does not play role of an independent predictive factor in terms of mutation frequency.

We report a case of 46-year-old male operated on for moderately differentiated lung adenocarcinoma. Postoperatively, he underwent six courses of chemotherapy and radiotherapy. He developed progressive severe inferior paraparesis accompanied by excruciating pain between the shoulders two years later. Magnetic resonance imaging revealed metastases in the bodies of T2 and T3 vertebrae with adjacent intradural extramedullary lesion compressing the spinal cord. The patient underwent surgical decompression and vertebral body cement augmentation that lead to pain relief and partial neurological recovery. The histological examination was consistent with metastases from low differentiated pulmonary adenocarcinoma. Surgical resection of intradural extramedullary metastasis improves patient quality of life by reducing pain intensity and neurological deficit.

Background:Invasive mucinous lung adenocarcinomas are rare and account for 2%–10% of all lung adenocarcinoma cases. It is believed that Napsin A exhibits a weaker expression in mucinous adenocarcinomas compared with TTF1, but such correlation is still poorly researched.Aim:The aim of the study was to determine the frequency of mucinous to nonmucinous adenocarcinomas and compare specificity and sensitivity of monoclonal Napsin A with TTF1 in mucinous adenocarcinomas and define the frequency of EGFR mutations.Materials and methods:Eighty-four resected lung carcinomas were prospectively evaluated. All biopsies were analysed with p63, TTF1, monoclonal Napsin A, CK7, CK20 and CDX2 and were studied with real-time PCR technology.Results:In resected material we detected 49/84 (58.3%) adenocarcinomas and selected 21 mucinous adenocarcinomas out of 46 non-mucinous adenocarcinomas (45.6%). The most common pattern of mucinous adenocarcinomas is papillary - 24% and colloidal - 24%, followed by acinar - 19.2% and lepidic - 19.2%. mNapsin A was positive in 18/21 (85.7%) mucinous adenocarcinomas v/s 17/21 TTF1 positive (80.9%). EGFR mutations were detected in 3/21 cases with mucinous adenocarcinomas (14.3%): mucinous papillary, mucinous acinar and “salivary gland-like”.Conclusion:Our study demonstrates a high proportion of primary mucinous lung adenocarcinomas to primary non-mucinous adenocarcinomas. Sensitivity and specificity of mNapsin A and TTF1 did not show significant difference in pulmonary mucinous and non-mucinous adenocarcinomas, as mNapsin A gave greater sensitivity to mucinous adenocarcinomas. Our results indicate the same mutation frequency of EGFR in mucinous adenocarcinomas as mutation frequency detected in non-mucinous adenocarcinomas in the Bulgarian region.