A strain or other form of trauma is sometimes blamed for the onset of lymphadenitis, especially in the glands of the groin (bubo), but it is usually possible to discover some source of pyogenic infection which is responsible for the mischief, or to obtain a history of some antecedent infection such as gonorrhoea.  It is possible for gonococci to lie latent in the inguinal glands for long periods, and only give rise to lymphadenitis if the glands be subsequently subjected to injury.  The glands most frequently affected are those in the neck, axilla, and groin.

The characters of the lymphadenitis vary with the nature of the irritant.  Sometimes it is mild and evanescent, as in the glandular enlargement in the neck which attends tonsillitis and other forms of sore throat.  Sometimes it is more persistent, as in the enlargement that is associated with adenoids, hypertrophied tonsils, carious teeth, eczema of the scalp, and otorrhoea; and it is possible that this indolent enlargement predisposes to tuberculous infection.  A similar enlargement is met with in the axilla in cases of chronic interstitial mastitis, and in the groin as a result of chronic irritation about the external genitals, such as balanitis.

Sometimes the lymphadenitis is of an acute character, and the tendency is towards the formation of an abscess.  This is illustrated in the axillary glands as a result of infected wounds of the fingers; in the femoral glands in infected wounds or purulent blisters on the foot; in the inguinal glands in gonorrhoea and soft sore; and in the cervical glands in the severer forms of sore throat associated with diphtheria and scarlet fever.  The most acute suppurations result from infection with streptococci.

Superficial glands, when inflamed and suppurating, become enlarged, tender, fixed, and matted to one another.  In the glands of the groin the suppurative process is often remarkably sluggish; purulent foci form in the interior of individual glands, and some time may elapse before the pus erupts through their respective capsules.  In the deeply placed cervical glands, especially in cases of streptococcal throat infections, the suppuration rapidly involves the surrounding cellular tissue, and the clinical features are those of an acute cellulitis and deeply seated abscess.  When this is incised the necrosed glands may be found lying in the pus, and on bacteriological examination are found to be swarming with streptococci.  In suppuration of the axillary glands the abscess may be quite superficial, or it may be deeply placed beneath the strong fascia and pectoral muscles, according to the group of glands involved.

The diagnosis of septic lymphadenitis is usually easy.  The indolent enlargements are not always to be distinguished, however, from commencing tuberculous disease, except by the use of the tuberculin test, and by the fact that they usually disappear on removing the peripheral source of irritation.