Write a short note on Cold Abscess.

Definition

A cold abscess is a collection of tuberculous pus (caseous material) that forms without the classic signs of acute inflammation — hence ‘cold’: there is no heat, redness or acute tenderness, unlike a pyogenic (‘hot’) abscess. It is a hallmark of skeletal tuberculosis, especially of the spine.

Formation & Behaviour

Caseation and liquefaction in a tuberculous focus produce pus that, under gravity and along tissue planes, tracks far from its origin before pointing. A classic example is a psoas abscess from lower thoracic/lumbar Pott’s disease, which follows the psoas sheath to present as a swelling in the groin or iliac fossa, or a retropharyngeal abscess from cervical spine disease. It is characteristically fluctuant but painless and cool.

Management

The cornerstone is anti-tuberculous chemotherapy directed at the underlying disease. Small abscesses resorb on treatment; larger or symptomatic ones may be aspirated (avoiding a dependent drainage track) or drained at the time of spinal decompression. Confirm the diagnosis by AFB smear, culture and GeneXpert on the aspirate.

Contrast with a Pyogenic Abscess

The distinction from a pyogenic (‘hot’) abscess is fundamental. A pyogenic abscess is acute, hot, red, tender and systemically toxic, forming close to its origin. A cold abscess is chronic, cool, painless and fluctuant, forms in the setting of constitutional TB symptoms, and characteristically migrates along fascial planes. Recognising the ‘cold’ nature prevents inappropriate incision and points to an underlying tuberculous focus that must be sought and treated.

Absence of inflammatory signs gives it the name.

• Cold abscess = tuberculous pus without heat/redness (cf. Hot pyogenic abscess).
• Tracks along fascial planes under gravity (e.g. Psoas abscess to the groin).
• Hallmark of skeletal TB, especially spinal (Pott’s) disease.
• Treat the underlying TB with chemotherapy; avoid dependent incision (sinus risk).