Aetiology:

1. Infections due to tuberculosis and fungi like blastomycosis.
2. Persons with hyperimmunoglobulin E syndrome.

Pathology

Three stages:

• 1)Stage of lymphadenitis: Painless, mobile, discrete lymph nodes.

• 2) Stage of periadenitis: Mass of the matted node fixed to the skin.
• 3) Late stage: The node can undergo several changes by

1. Healing by fibrosis.
2. Caseation and liquefaction.
3. Cold abscess bursting either through deep fascia into subcutaneous tissue forming collar stud abscess or forming a sinus through skin.

Cold Abscess Clinical features

• History of softening following a pre-existing solid neck swelling.
• Nodes mainly in the posterior triangle.
• Absence of signs of inflammation.
• Constitutional symptoms of tuberculosis like evening rise of temperature, anorexia, weight loss.
• Secondary infection of the abscess.

• Matted lymph nodes palpable on deeper aspect.
• Aspiration reveals caseous material.
• Tenderness of cervical spine may be present if bony involvement.

Cold Abscess Investigations

1. Complete blood count shows lymphocytosis.
2. ESR is raised.
3. Tuberculin test is positive.
4. X ray chest.