A diaphragmatic hernia can be defined as the collapsing of the contents of the abdominal cavity into thethorax as a result of a diaphragmatic defect. Most often it is congenital, but can also be acquired. Congenital hernia is a foetal defect that is most often diagnosed before birth by ultrasound or in newborns, and forms during intrauterine growth.The cause of congenital hernia is the abnormal development of tissues and the walls of body cavities. On the other hand, an acquired diaphragmatic hernia occurs after a blunt or penetrating injury in which the diaphragm ruptures and is accompanied by a hernia of the abdominal contents. Acquired diaphragmatic hernia may appear spontaneously or as a result of iatrogenic causes. Acquired diaphragmatic hernia is quite rare, but is very dangerous, causing entrapment and suffocation, and can be associated with high mortality.

Mantle cell lymphoma (MCL) is an aggressive, rare form of non-Hodgkin lymphoma (NHL). This lymphoma is characterized by the expansion of mature B cells which spread in the bone marrow, blood, lymphatic tissues and extranodal sites. Due to limited treatment options, it is one of the most complex neoplastic diseases of the lymphoid system. The typical age of onset is 60-70 years. Occasionally, tumour lysis syndrome (TLS) can occur due to the cancer cells breaking-down too quickly. The sudden, intense breakdown of the cancer cells releases large amounts of potassium, purines and phosphates. In the clinical case described by the authors, the patient was diagnosed with MCL in the generalized CS III stage. The patient additionally developed TLS. Previously, the patient had been treated with rituximab at the Department of Haematooncology, and due to respiratory and renal failure, was subsequently admitted to the Intensive Care Unit (ICU) of the University Hospital in Lublin.