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Langhans’ giant cells




Large cells with many nuclei, often in a ‘horseshoe’ formation.  These cells are regularly seen in tuberculous lesions but also occur in granulomas due to other conditions.

Laryngoscopy



Examining the larynx (voice box) and vocal chords – usually done by using mirrors, fibre-optic instruments or a purpose-built device called a laryngoscope.

Lassitude

Weakness, exhaustion.

Latent tuberculosis



A term applied to the status of those infected with the tubercle bacillus but remaining healthy.  It is assumed that the tubercle bacilli are in some dormant or resting ‘persister’ state, although the exact nature of this state is hotly debated.

Liquid Media (Liquid Culture)



Specimens can be cultured using either solid or liquid nutrient materials (culture) for the bacteria to grow in. Liquid media are used as an alternative to solid media particularly in automated culture systems that provide results more rapidly than conventional culture techniques based on solid media.

Live vaccine



Vaccines which contain living microbiological organisms, including BCG, measles, mumps, rubella and polio.

Löwenstein-Jensen medium



The most widely used culture medium for isolation of tubercle bacilli and other mycobacteria. It has been described as ‘a hard boiled egg with the addition of glycerol and a few mineral salts’.

Lupus vulgaris



A very chronic and disfiguring form of skin tuberculosis usually affecting the face. The term intrigued the famous German pathologist Rudolf Virchow who traced its use back to the 10th century but not to its origin.  The word lupus is, in this context, thought to be a corruption of lepros – a term applied in the past to many skin conditions and not just to leprosy.

Lymphadenitis



Inflammation of a lymph node. Tuberculous lymphadenitis is one of the commonest forms of extra-pulmonary tuberculosis. The lymph nodes of the neck (cervical nodes) are the most frequent site.

Lymphadenopathy

Disease of the lymph nodes. Often used synonymously with lymphadenitis.

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