Glossary

lactate dehydrogenase (Abrev.: LDH)
enzyme that plays a role as part of a metabolic process (lactic acid fermentation) in all cells and organs and is also detectable in the blood; an elevated LDH level in the blood can indicate cell damage in the body and (among other conditions) occur in many benign and malignant diseases or injuries.
Example / Relevance Pediatrics: LDH can be determined as an (additional) marker if a malignant tumour is suspected, or after tumour detection for monitoring and follow-up.

laparoscopy
examination of the abdominal cavity with a special endoscope, which is inserted through the abdominal wall under anesthesia by means of a minor surgical procedure
Example / Relevance Pediatrics: in the context of cancer diagnostics, laparoscopy is used as a diagnostic procedure for the assessment of lymph nodes and organs in the abdomen and pelvis, also with the removal of tissue samples (biopsy). This technique is particularly used if sufficient information cannot be provided by imaging techniques.

laparotomy
surgical opening of the abdominal cavity
Example / Relevance Pediatrics: rare diagnostic procedure for the evaluation of lymph nodes and organs in the abdominal and pelvic cavity in the context of cancer diagnosis, also with the removal of tissue samples (biopsy).

laser beam
sharply focused, very high-energy light of one wavelength; when it reaches organ tissue, the energy is released as heat. Lasers can therefore be used for the precise boiling, melting or cutting of tissue. Laser is the abbreviation for "light amplification by stimulated emission of radiation".
Example / Relevance Pediatrics: laser is used to widen tumour-related narrowing of hollow organs or vessels in the lung area or to remove tumours (see e.g. laser coagulation in retinoblastoma).

laser therapy syn. laser coagulation
melting of tissue by the heat effect of the laser beam; is used in the removal of tissue parts and in the obliteration of vessels.
Example / Relevance Pediatrics: possible form of (local) treatment, e.g. for retinoblastoma

leukaemia
malignant disease of the blood forming (haematopoietic) system and the most common cancer in children and adolescents (about 33%); depending on the origin of the malignant cells, a distinction is made between lymphoblastic and myeloid leukaemias. Depending on the course of the disease (fast or slow), a distinction is made between acute and chronic leukaemias.

leukocytes
white blood cells; they serve as cells of the immune system, defending against pathogens and fighting infections. In addition, they remove the cell debris produced by the decay of body cells. Leukocytes include granulocytes (with 60 – 70 %), lymphocytes (20 – 30 %) and monocytes (2 – 6 %). Leukocytes are mainly produced in the bone marrow. This process is called leucopoiesis.

leukopenia
decreased white blood cells (leukocytes) in the blood to levels below the age-appropriate norm;
Example / Relevance Pediatrics: leukopenia can be a consequence of immunosuppression by cytostatic drugs.

Li-Fraumeni syndrome
cancer predisposition syndrome characterized by the increased occurrence of various solid tumours within a family; in childhood and adolescence, tumours of the adrenal glands, as well as soft tissue sarcomas, leukaemias and CNS tumours are most commonly observed, in adulthood mainly bone tumours (osteosarcomas), breast cancer and lung tumours. In most cases, there is a change (mutation) of the so-called tumour suppressor gene TP-53 (protein p53).

light microscope
a microscope that uses light to produce highly magnified images of small objects, thus allowing the detection of structures that are not visible to the naked eye; magnification is done by exploiting the refraction of light on the microscopes lens system.
References: microscope

lipoma
benign tumour that develops from cells of adipose tissue

live vaccine syn. live attenuated vaccine, attenuated vaccine
vaccine made from live, i.e. reproducible, but weakened pathogens (viruses); it serves to prevent a corresponding infectious disease. The live vaccination is an active vaccination.
Example / Relevance Pediatrics: Live vaccines are used to immunise against measles, mumps, rubella or polio, for example. In people with healthy immune systems, the vaccines do not cause disease. Immunocompromised patients after cancer therapy, on the other hand, are still at high risk of infection for some time, so that vaccination with live vaccines should only be given after a defined period of time following cancer treatment.
References: infection - rubella - measles - virus

Louis-Bar syndrome
hereditary disease; it is mainly characterized by degeneration of the central nervous system (CNS), an impairment of the immune system (immunodeficiency), dilated blood vessels of the eyes and skin (so-called telangiectasias) and an increased risk of cancer (so-called cancer predisposition syndrome). Degeneration of the CNS is associated with various neurological disorders, such as movement disorders (ataxia) and abnormal eye movements. The immunodeficiency often causes recurrent infections.

lumbar puncture
puncture of the spinal canal in the lumbar spine, e.g. to remove cerebrospinal fluid (CSF) or for the purpose of administering medication (so-called intrathecal treatment); in the case of cancer, a sample and examination of cerebrospinal fluid can be used to detect malignant cells; in the case of increased intracranial pressure due to a CNS tumour, cerebrospinal fluid removal (CSF) is also used to relieve pressure.

lymph nodes
small lenticular to bean-shaped organs that are part of the bodys immune system and are located in many parts of the body; they serve as filter stations for the tissue water (lymph) of a region of the body and contain cells of the immune system.

lymphangioma
rare, benign tumour disease of the lymphatic vessels, which usually occurs in early childhood; lymphatic vessels in the neck and neck area as well as the armpits are most commonly affected. The patient can be successfully treated by complete surgical removal of the mass. Alternative treatment options are laser and pharmacological therapy, consisting of repetitive injections of a specially treated bacterial strain (Streptococcus pyogenes) into the lymphangioma (sclerotherapy). The treatment ultimately leads to scarring and sclerosis of tissues and vessels.

lymphatic system
collective term for lymphatic vessels, lymphatic vessel trunks, lymph nodes, lymphatic tissues (lymphocytes in connective tissue, mucous membranes, glands) and lymphatic organs (spleen, pharyngeal tonsils, bone marrow, thymus gland).

lymphoblasts syn. blasts
immature (here also degenerated) progenitor cells of lymphocytes

lymphocytes
subgroup of white blood cells that are responsible for the bodys own defenses, especially the defense against viruses; there are B and T lymphocytes. They are formed in the bone marrow, but partly only mature to full functionality in the lymphatic tissue (e.g. lymph nodes, spleen, thymus gland). They eventually enter the blood via the lymphatic vessels, where they take over their respective tasks.

lymphoma
collective term for lymph node enlargement of various causes