COLD ABSCESS
Dr. P.Sudheer kumarOrthopaedics postgraduate
Narayana medical college & hospital
Introduction
An Abscess is a collection of pus within the body.
It is cold because it is not accompanied by the classical signs of inflammation
Almost always a sequel of tubercular infection anywhere in the body commonly in the lymph nodes & bone.
Pathogenesis
Any osteoarticular tubercular lesion is a result of a hematogenous dissemination from a primarily infected visceral focus
Primary focus may be in Lungs,lymph glands of mediastinum/mesentry/cervical region or kidneys or other viscera.
Phagocytosis of tubercle bacilli by RES
Pathogenesis
The characteristic microscopic lesion is the tuberculous granuloma– a collection of epithelioid and multinucleated giant cells periphery.
Within the tubercle, small patches of caseous necrosis appear. These may coalesce into a larger yellowish mass, or the centre may break down to form an Abscess.
Pathogenesis
Polymorpho nuclear cells
Macrophages & monocytes
Langhans giant cellsCentral caseation
necrosis
Cold abscess
Histology
Pathology
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 distant sites
Composition
Mostly composed of -serum -leucocytes -caseous material -bone debris -tubercle bacilli
Sites
Commonly at Neck & Axilla
Also at Groin,back,side of chest wall
These are sequel of tubercular infection of spine,ribs & posterior medistinal group of lymph nodes.
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 , weight loss,loss of appetite
Symptoms of primary tuberculosis
Clinical features… Local Pressure effects due to swelling
c-spine: exudate collects behind prevertebral fascia & protrude as retropharyngeal abscess causing dysphagia, dysphonea, hoarseness of voice & respiratory obstruction
abscess may track down to enter trachea, esophagus or pleural cavity. It may spread laterally into the sternomastoid muscle & forms an abscess in the neck.
Clinical features… T-spine: exudate 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.
Clinical features… 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 it.(pseudo hip flexion)
Can gravitate beneath inguinal ligament to appear on the medial aspect of thigh
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-6 , sensitivity of 60% – 80%.
PCR
Fnac & Biopsy
Percutaneous , CT scan ; 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 50% of cases.
Radiological diagnosis
1. PLAIN RADIOGRAPH 2.ULTRASOUND 3. CT SCAN 4. MRI SPINE 5.BONE SCAN
Plain Radiograph
Cervical region - b/w vertebral bodies , pharynx and trachea Upper thoracic - ‘V’ shaped shadow , stripping lung apices laterally and downwards Below T4 – fusiform shape (bird nest
appearence) Below diaphragm – unilateral / bilateral
psoas shadow
Plain Radiograph…
ULTRASOUNDDetect cold abscess A HYPO ECHOEIC LESIONInternal echoes represent debris within. Guided aspiration
CT IMAGE
Patterns of bony destruction.Calcifications in abscess (pathognomic for Tb)
MRI •Assessment of extradural abscesses / subligamentous spread.•Skip lesions•Spinal cord involvement.
Radionucleotide Scan T 99m Increased uptake in up to 60 per cent
patients with active 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
Same as tuberculosis elsewhere in the body. The chemotherapy is continued for 18 months.
Drug: Dosage: Side effects:
Rifampicin: 450-600mg Liver toxicity
Isoniazid 300-450mg peripheral neuritis
Pyrizanamide: 40mgms/kg Liver toxicity.
hyperuricemia
Ethambutol: 15-25mgms/kg. Optic neuritis.
Streptomycin(inj) 20mgms/kg vestibular damage,
nephrotoxicity
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
Correcting underlying bony lesion/defect.