Thrombotic microangiopathy (TMA) is an anatomopathological lesion mediated by endothelial dysfunction and characterized by the creation of microthrombi in small vessels. In patients with cancer, it may be due to toxicity secondary to chemotherapy, tumor embolization, or hematopoietic progenitor transplantation. Cancer-associated TMA is an underestimated entity that generally appears in the final stages of the disease, although it may also be the initial manifestation of an underlying cancer. Support treatment is necessary in all cases and, depending on the cause, different targeted therapies may be used. The prognosis is very poor. In this article we present a comprehensive review of the existing literature on the physiological mechanisms of cancer-associated TMA. Afterwards, five clinical cases will be presented of patients who developed TMA and were diagnosed in our Department in 2023. We present a discussion of the different causes that triggered the condition, the possible reasons behind the underestimation of this pathology, and the measures that may be adopted.

Background and Objective: The implementation in routine clinical practice of PD-L1 expression analysis and new massive sequencing techniques (NGS) has resulted in the creation of a molecular classification that leads on the most appropriate treatment for non-small cell lung cancer (NSCLC) is decided. Nowadays, specific treatments approved first-line against different mutations such as those targeting the EGFR, ALK, ROS1, KRAS, BRAF, RET or MET genes are commercially available. In this literature review we analyze the importance of the KRAS oncogene as a clinical biomarker in patients with NSCLC, its implication as a predictor of response to immunotherapy and the difficulties in developing specific drugs that act against mutations in this oncogene. Methods: The narrative review was conducted and carried out using the quality standards of narrative or literature review current guidelines. The reviews, clinical trials and studies included were found through searching several databases: PubMed, Cochrane, Science Direct, EMBASE, and the clinical trial registry (www.clinicaltrials.gov). The studies reviewing the main clinical trials that resulted in the approval of targeted therapies in NSCLC KRAS mutated and then the immunotherapy treatment in this type of lung cancer. Key Content and Findings: KRAS oncogene is one of the most frequently altered oncogenes in human cancers. In NSCLC it is altered in 20–30% of cases. In recent years, the identification of a new allosteric binding site in KRAS G12C has allowed the development of irreversible covalent inhibitors that have demonstrated their efficacy in daily clinical practice. However, other frequent mutations such as KRAS G12D and KRAS G12V still lack approved drugs although promising results have already been obtained in in-vitro and in-vivo clinical trials. There also appears to be a greater efficacy of response to immunotherapy in KRAS-mutated NSCLC, although this is a field under study. Conclusions: The KRAS gene has fundamental implications in NSCLC, both at the molecular and clinical levels. The correct and thorough characterisation of the different alterations and mutations of the KRAS gene will open up new avenues in the treatment of KRAS-mutated NSCLC, as well as personalising immunotherapy treatments in patients with these alterations.

Summary: Anti PD1/PD-L1 agents, including pembrolizumab, have revolutionized the oncological treatment of different types of cancer, including non-small cell lung cancer. The most frequent complications associated with this type of treatment are mild and are located at the thyroid, pulmonary or hepatic level. Sarcoid like reaction and mesenteric panniculitis secondary to pembrolizumab treatment are two very rare adverse effects. We present the case of a patient with these complications. Purpose: the treatment of metastatic non-small cell lung cancer has undergone a major change in the last 10 years, largely due to the advent of immunotherapy. Anti PD1 agents such as pembrolizumab have increased the median survival of these patients from 13 to 26 months. Most frequent immunorelated side effects are hypothyroidism, pneumonitis or elevated liver enzymes. However, there are other adverse effects, including sarcoid-like reaction and mesenteric panniculitis, which should be known by the professionals involved in the diagnosis and treatment of this type of patient. We present the case of a 62-year-old man with a history of unresectable and non-irradiable stage IIIB epidermoid lung carcinoma with a PD-L1 expression of 30% in whom pembrolizumab was discontinued after 4 cycles due to immunorelated arthritis. One year later he consulted for severe abdominal pain. A PET-CT scan was performed, showing hilar lymphadenopathy and inflammation of abdominal mesenteric fat. A biopsy of lesions in both areas showed non-necrotizing granulomatous lymphadenitis in hilar adenopathy and patchy fibrosis of mesenteric fat. The picture was classified as sarcoidosis-like reaction and mesenteric panniculitis secondary to pembrolizumab. Anti-PD1 agents cause hyperactivation of the immune system through T-cell proliferation. Sarcoid-like reaction is a very rare complication that can mask progressive tumor disease. Awareness of immunorelated complications by oncologists, internists, and radiologists is important for an appropriate diagnostic approach and targeted test ordering.

Introduction: Kaposi’s varicelliform eruption (KVE), also known as eczema herpeticum or eczema vaccinatum, is an acute dermatosis that affects patients with chronic dermatopathies. The diagnosis is primarily clinical and is characterised by the presence of a vesicular exanthema on physical examination. The exanthema subsequently evolves into crusted lesions with typical circular ulcerations in ‘punched-out’ areas on the skin affected by the underlying dermatopathy. Case description: We present the case of a 6-year-old patient who presented to the Paediatric Emergency department with skin lesions consistent with eczema herpeticum. The patient’s management was initially outpatient; however, due to the slow progression of the condition, hospitalisation and intravenous antiviral treatment were initiated. Discussion: KVE affects patients with chronic dermatoses, especially atopic dermatitis. It is important to know the clinical presentation for an early suspicion. KVE is a medical emergency that requires prompt diagnosis and treatment. It can progress to secondary viraemia, which can be fatal in up to 10% of immunocompetent individuals and up to 50% of immunocompromised individuals. It is important to be aware of this condition and to start early treatment with antivirals, especially given the high prevalence of atopic dermatitis in our population. This condition is one of the most serious complications that can occur in these patients.