thumb | 220x124px | right | alt= A person's neck is shown. At the base of the neck is a dark colored depression in the skin, around which the neck is heavily inflamed. The skin at the base of the neck and the top of the chest is rashed and discolored. | A case of long-standing tubercular lymphadenitis
Peripheral tuberculous lymphadenitis (or tuberculous adenitis) is a form of tuberculosis infection occurring outside of the lungs. In general, it describes tuberculosis infection of the lymph nodes, leading to lymphadenopathy. When cervical lymph nodes are affected, it is commonly referred to as "Scrofula." A majority of tuberculosis infections affect the lungs, and extra-pulmonary tuberculosis infections account for the remainder; these most commonly involve the lymphatic system. Although the cervical region is most commonly affected, tuberculous lymphadenitis can occur all around the body, including the axillary and inguinal regions. Granulomatous tubercules eventually develop central caseous necrosis and tend to become confluent, replacing the lymphoid tissue.
Epidemiology
The exact prevalence of tuberculous lymphadenitis varies between countries and regions, with higher rates seen in developing countries. Historically, transmission of Mycobacterium bovis from dairy consumption was another frequent cause of tuberculous lymphadenitis, but incidence has drastically decreased in developed countries since the advent of pasteurization and other efforts to prevent bovine tuberculosis. The characteristic morphological element is the tuberculous granuloma (caseating tubercule): giant multinucleated cells (Langhans cells), surrounded by epithelioid cells aggregates, T cell lymphocytes and few fibroblasts. Granulomatous tubercules evolve to central caseous necrosis and tend to become confluent, replacing the lymphoid tissue.
Diagnosis
thumb|Basic steps of the Ziehl-Neelsen staining procedure. This acid-fast staining method, in conjunction with [[Auramine phenol stain|auramine phenol staining, serves as a standard diagnostic tool and is widely used for rapidly diagnosing tuberculosis, leprosy, and Mycobacterium avium-intracellulare infection.]]
The gold standard for diagnosis of tuberculous lymphadenitis is to obtain a culture, though results may take weeks. A positive acid-fast bacteria (AFB) stain can support the diagnosis.