COLD ABSCESS-DR. PRAPULLA CHANDRA

• INTRODUCTION•PATHOGENESIS• SITES•CLINICAL FEATURES•DIFFERENTIAL DIAGNOSIS• INVESTIGATIONS• TREATMENT•CASE REPORTS

Introduction• An Abscess is a collection of liquefied tissue(pus) in the

body, which is body’s defense reaction to foreign material.

• Cold abscess comes from the Gothic word "kalds" meaning "cold" and the Latin word “abscessus” meaning “ going away.” • together means “ going away cold.”

• It is called cold abscess because it is not accompanied by the classical signs of inflammation- heat, redness, fever, pain etc., which are usually found with pyogenic abscess.

•More commonly, a sequelae of tubercular infection elsewhere in the body commonly in the lymph nodes & bone.

OTHER CAUSES• Actinomycosis• Leprosy• Fungal infections like Blastomycosis• Hyperimmunoglobulin E syndrome (job’s syndrome) -recurrent staphylococcal cold abscess -eczema -increased Ig E

Pathogenesis• Any osteoarticular tubercular lesion is result of a

hematogenous dissemination from a primarily infected visceral focus

• Primary focus may be in Lungs, lymph nodes of cervical region/mediastinum/mesentery, kidneys or other viscera.

• Phagocytosis of tubercle bacilli by RES

• The characteristic microscopic lesion is the tuberculous granuloma– a collection of epithelioid and multinucleated giant cells in the periphery.

•Within the tubercle, small patches of caseous necrosis appear. These may coalesce into a larger yellowish mass and the centre may break down to form an Abscess.

Pathogenesis

Polymorpho nuclear cells Macrophages & monocytes

Langhans giant cells Central caseation necrosis

Cold abscess

HISTOLOGY

FROM VERTEBRAL TB• It develops as an exudative lesion due to hypersensitivity

reaction to mycobacterium tuberculosis.

• It is formed by collection of products of liquefaction & the reactive exudation

• It penetrates the ligaments in articular disease, bone & periosteum in osseous disease

•Migrates in various directions following the path of least resistance along fascial planes, blood vessels and nerves to appear superficially at distant sites away from the site of lesion.• Spinal TB presents more commonly as - clinical kyphosis 95% - palpable cold abscess 20% - radiological paravertebral abscess 21% - tubercular sinuses (active/healed) 13%

FROM TB LYMPHADENITIS• In the initial stages, the nodes may be discrete.

• Periadenitis results in matting and fixity of lymph nodes.

• The lymph nodes coalesce and breakdown to form caseous pus which may perforate the deep fascia and present as fluctuant swelling on the surface.

• The overlying skin becomes indurated, breaks down and leads to the formation of a sinus.

• Healing occurs with calcification and scarring.

•Without treatment, it may remain unhealed for years.

LYMPH NODE ABSCESS

Composition• Mostly composed of • -serum• -leucocytes• -caseous material• -bone debris• -tubercle bacilli

Sites• Commonly at Neck & Axilla

• Also at loin, back, side of chest wall

• These are sequelae of tubercular infection of spine,ribs & posterior medistinal group of lymph nodes.

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REGIONAL DISTRIBUTION

• CERVICAL 12%• CERVICODORSAL 5%• DORSAL 42%(THORACIC)• LUMBAR 26%• DORSOLUMBAR 12%• LUMBOSACRAL 3%

CLINICAL FEATURES• Painless Swelling -insidious onset -soft & smooth mass -cystic consistency -fluctuation present -slip sign negative -No transillumination

Clinical features…• Sinus or ulcer

• superadded infection with pyogenic organisms

• Constitutional symptoms like low grade fever, cough , loss of weight & loss of appetite

• Symptoms of primary tuberculosis

Local Pressure effects due to swelling

c-spine: the exudate collects behind prevertebral fascia &

protrude forward as retropharyngeal abscess causing -dysphagia, -dysphonea, -dyspnoea, -hoarseness of voice

• The abscess may track down in mediastinum to enter trachea, esophagus or pleural cavity. It may spread laterally into the sternomastoid muscle & forms an abscess in the neck.

T-spine: • The exudate may be confined locally as paravertebral

abscess

• it may enter into spinal canal & compress spinal cord leading to Early onset pott’s paraplegia

• it can penetrate anterior longitudinal ligament to form mediastinal abscess .

• pass downwards through medial arcute ligament to form a lumbar abscess.

•Rarely, the thoracic cold abscess may follow the intercostal nerve to appear anywhere along the course of nerve.

Granuloma formationTissue necrosis & inflammatory response

Paraspinal Abscess

Localized Track along tissue planes

Progressive necrosis of vertebral body-Kyphotic deformity

Adjacent vertebral bodies under the longitudinal ligaments

Along the fascial planes Ex: Psoas abscess

PARAVERTEBRAL ABSCESS

Lumbar spine:• abscess can have pus track along the psoas muscle towards

the groin & presents as psoas abscess

• Flexion deformity of hip can develop due to the abscess(pseudo flexion deformity of hip)

• Can gravitate beneath the inguinal ligament to appear on the medial aspect of thigh

• It can spread laterally beneath iliac fossa to emerge at the iliac crest near the anterior superior iliac spine.

• The exudate can follow vessels to form an abscess in scarpa’s triangle or gluteal region.

Differential diagnosis• Pyogenic abscess

• Lipoma

• cyst

• Soft tumors

Investigations• Lab studies

•Microbiology studies to confirm diagnosis

• Radiological diagnosis

Lab studies•Mantoux / Tuberculin skin test

• ESR may be markedly elevated (neither specific nor reliable).

• ELISA : for antibody to mycobacterial antigen. sensitivity of 60% – 80%.

• PCR assays

FNAC & BIOPSY• Percutaneous CT ̶ guided needle biopsy of bone lesions is a

safe procedure that also allows therapeutic drainage of large paraspinal abscesses

• Biopsy is confirmative

Microbiology studies to confirm diagnosis

• Ziehl-Neelsen staining: Quick and inexpensive method. • Bone tissue or abscess samples stain for acid-fast

bacilli (AFB), & isolate organisms for culture & drug susceptibility.

• Culture results - few weeks. • Positive only in 60% of cases.

Radiological diagnosis 1. PLAIN RADIOGRAPH 2.ULTRASOUND 3. CT SCAN 4. MRI SPINE 5.BONE SCAN

PLAIN RADIOGRAPH

• Cervical region - retropharyngeal abscess may be seen on lateral x-ray. -soft tissue shadow thickness in front of C3 vertebra >4mm indicates retropharyngeal abscess.

•Thoracic region - A paravertebral shadow on AP view indicates paravertebral abscess. it may be of -fusiform shape (bird nest abscess) – length > width -globular or tense abscess – width > length

FUSIFORM ABSCESS TENSE ABSCESS

ULTRASOUNDDetect cold abscess A HYPO ECHOEIC LESIONInternal echoes represent debris within. Guided aspiration

CT IMAGEPatterns of bony destruction.Calcifications in abscess (pathognomic for Tb)

PARAVERTEBRAL ABSCESS

PSOAS ABSCESS

MRI •Assessment of extradural abscesses / subligamentous spread.•Skip lesions•Spinal cord involvement.

Radionucleotide Scan Tc 99m

• Increased uptake in upto 60 percent patients with active bone tuberculosis.

• Avascular segments and abscesses show a cold spot due to decreased uptake.

• Highly sensitive but nonspecific.

• Aid to localise the site of active disease and to detect multilevel involvement

TREATMENT• Anti tubercular drugs• Aspiration• Ultrasound guided Pigtail catheter drainage• Surgical management

ANTI TUBERCULAR DRUGS-Treatment is same as TB elsewhere in the body.

-With anti tubercular drug therapy, small cold abscesses heal along with bone/lymphnode tb.

Aspiration

•Palpable Cold abscess must be drained as early as possible & instil 1gm Streptomycin +/- INH in solution

•Technique: Zig-Zag aspiration using Wide bore needle from non-dependent area to prevent sinus formation

Ultrasound guided Pigtail catheter drainage

Surgical • Open drainage may be performed if aspiration failed to clear

it.

• Drainage using non-dependent incision,later closure of wound without placing a drain to prevent sinus formation.

• Correcting underlying bony lesion/defect.

•Cold abscess of chest wall sometimes may require rib resection, clavicle and sternum resection along with abscess excision.

CASE REPORTS

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