The pleural and peritoneal cavity share many related features due to their common celomic origin. Normally these two spaces are completely separated with the development of the diaphragm. Defects in diaphragm morphogenesis may result in congenital diaphragmatic hernias, which is the most known form of communication between the pleural and peritoneal cavity. However, in several cases, findings of pleuroperitoneal communication (PPC) have been described in adults through an apparently intact diaphragm. In this comprehensive review we systematically evaluate clinical scenarios of this form of “unexpected” PPC as reported in the literature and focus on the possible mechanisms involved.

This narrative review explains the history of anaphylactic or hypersensitivity reactions, their connection to the cardiovascular system, and Kounis syndrome, which is linked to hypersensitivity. Additional subjects discussed include immunoglobulin E and serum tryptase, common pathways of allergic and nonallergic cardiovascular events, current perspectives on Kounis syndrome, allergic myocardial infarction, allergic angina, and the impact of COVID-19 and its vaccination on Kounis syndrome. Kounis syndrome is a distinct kind of acute vascular disease that affects the coronary, cerebral, mesenteric, peripheral, and venous systems. Kounis syndrome is currently used to describe coronary symptoms linked to disorders involving mast cell activation and inflammatory cell interactions, such as those involving T-lymphocytes and macrophages, which further induce allergic, hypersensitive, anaphylactic, or anaphylactic insults. Platelet activating factor, histamine, neutral proteases like tryptase and chymase, arachidonic acid products, and a range of cytokines and chemokines released during the activation process are among the inflammatory mediators that cause it. Proinflammatory cytokines are primarily produced by mast cells in COVID-19 infections. Mast cell-derived proteases and eosinophil-associated mediators are also more prevalent in the lung tissues and sera of COVID-19 patients. As a modern global threat to civilization, COVID-19 is linked to chemical patterns that can activate mast cells; therefore, allergic stimuli are usually the reason. Virus-associated molecular patterns can activate mast cells, but allergic triggers are typically the cause. By activating SARS-CoV-2 and other toll-like receptors, a variety of proinflammatory mediators, including IL-6 and IL-1β, are released, potentially contributing to the pathology of COVID-19.

This narrative review explains the history of anaphylactic or hypersensitivity reactions, their connection to the cardiovascular system, and the Kounis syndrome, which is linked to hypersensitivity. Additional subjects discussed include immunoglobulin E and serum tryptase, common pathways of allergic and nonallergic cardiovascular events, current perspectives on Kounis syndrome, allergic myocardial infarction, allergic angina, and the impact of COVID-19 and its vaccination on Kounis syndrome. Kounis syndrome is a distinct kind of acute vascular disease that affects the coronary, cerebral, mesenteric, peripheral, and venous systems. Kounis syndrome is currently used to describe coronary symptoms linked to disorders involving mast cell activation and inflammatory cell interactions, such as those involving T-lymphocytes and macrophages, which further induce allergic, hypersensitive, anaphylactic, or anaphylactic insults. Platelet activating factor, histamine, neutral proteases like tryptase and chymase, arachidonic acid products, and a range of cytokines and chemokines released during the activation process are among the inflammatory mediators that cause it. Proinflammatory cytokines are primarily produced by mast cells in COVID-19 infections. Mast cell-derived proteases and eosinophil-associated mediators are also more prevalent in the lung tissues and sera of COVID-19 patients. Virus-associated molecular patterns can activate mast cells, but allergic triggers are typically the cause. By activating SARS-CoV-2 and other toll-like receptors, a variety of proinflammatory mediators, including IL-6 and IL-1β, are released, potentially contributing to the pathology of COVID-19.

Serum sickness-like reaction (SSLR) is a rare immune-mediated condition that typically affects the skin and joints after exposure to certain drugs, infections, or vaccines. Although it shares clinical similarities with serum sickness (SS), SSLR differs in its underlying mechanisms, histopathology, and causes. Despite its generally benign and self-limiting nature, SSLR is frequently misdiagnosed and may lead to unnecessary hospitalization. This narrative review summarizes current knowledge on epidemiology, pathophysiology, clinical features, diagnosis, treatment, and long-term considerations related to SSLR. The condition is most often associated with antibiotics, monoclonal antibodies, and vaccines, particularly in pediatric populations. Its pathogenesis remains incompletely understood, but proposed mechanisms include immune complex formation, altered drug metabolism, lymphocyte toxicity, and the development of anti-drug antibodies. Diagnosis is primarily clinical, although novel diagnostic tools are emerging. Management involves discontinuation of the offending agent and supportive care, such as antihistamines or nonsteroidal anti-inflammatory drugs (NSAIDs) in mild cases, and corticosteroids in more severe cases. Long-term management, especially in cases requiring potential re-exposure to the causative agent, remains challenging. Skin testing and graded oral challenges appear promising within a structured clinical framework. Increased awareness of SSLR is essential for timely recognition and appropriate care, and further research is needed to elucidate its mechanisms and inform evidence-based management strategies.

Background: Serum sickness-like reaction (SSLR) is a rare cause of drug eruption. The clinical presentation includes fever, rash, and arthralgia which typically occurs 1-2 weeks after the administration of common antibiotics such as amoxicillin or cefaclor. It is a challenging diagnosis because it mimics sepsis and other exanthematous diseases. Rapid Strep Test (RST) is a useful diagnostic test for detecting Streptococcus pyogenes in patients with pharyngitis and Centor score of 3 or more guiding the administration of antibiotics. The Case: We report a case of a 63-year-old female patient seen in the emergency department (ED) with high-grade fever, diffuse rash, musculoskeletal pain, and a positive RST without clinical evidence of pharyngitis. The primary care physician ordered the RST before the referral to the ED to investigate the febrile rash without a clear indication, misleading to the diagnosis of streptococcal sepsis. She was eventually diagnosed with SSLR and she was treated with corticosteroids, leading to rapid symptomatic relief. Conclusion: SSLR is an interesting clinical entity, and its pathogenesis is poorly understood. This case emphasizes that SSLR is a clinical diagnosis of exclusion after ruling out other similar disorders. Physicians should be familiar with this benign condition to avoid unnecessary diagnostic testing such as RST which may misguide diagnosis and treatment. Simple diagnostic tests should be used with caution under certain indications; misuse of RST can cause false-positive results, complicating the management of these cases.

Neonatal meningitis is associated with increased morbidity, mortality, and long-term consequences. Despite the use of newer techniques, the diagnosis remains challenging, especially in cases caused by rare pathogens. Campylobacter is widely known as the most common cause of bacterial gastroenteritis. However, invasive infections in neonates have been rarely described in the literature. A rare case of neonatal meningitis caused by Campylobacter coli is presented in this case report. A 14-day-old male and late preterm neonate without a remarkable perinatal history was admitted to our Pediatric Department with a 10-h history of fever and loose stools. The initial laboratory studies suggested the diagnosis of meningitis, but isolating the responsible pathogen in blood and cerebrospinal fluid cultures was demanding. After the cultures were repeated and incubated in microaerophilic conditions, Campylobacter coli was confirmed as the etiological agent. Based on antibiotic susceptibility tests, the neonate had a 21-day course of antibiotic therapy with cefotaxime, a third-generation cephalosporin, and remained healthy during the illness without experiencing any neurological sequelae. This case report highlights that rare pathogens should be considered and searched for in cases of neonatal meningitis when there is no identifiable cause with routine microbiological techniques.