Is a localized collection of pus in any part of the body, they are cased by a breach of surface of the skin or mucous membrane and the entrance through the breach of pyogenic organisms. Pathogenesis of Abscess: Wound (foreign body or local cellulitis) → pathogenic organisms → Imprisoned in any part of body→ Local inflammation → Fibrin → It binds the tissue with local inflammation and contamination → Tissue destruction → The development of a pus filled space → The pus is retained a long time → Its liquid portion undergoing absorption → Its solid portion becomes caseated → A still longer time calcified.

Note: The wall is at first formed of inflamed tissue, which gradually undergoes softening until the destruction process is arrested by bursting of the abscess. This limiting wall of the cavity forms an obstacle to general infection. It provides the phagocytes which keep the pyogenic organisms in check. Abscesses may by classify as virulent: 1) Hot or Acute abscess: It forms after a period of there to 3-5 days from the start of the infection. It may be composed of a wall or pyogenic membrane and contents or pus. The character of the pus varies according to the tissue involved and the organisms it contains. It may also be classified as:

B) Deep abscess: It usually develops under thick layers of tissue. No local inflammation may be noticed. Attention is usually first drawn by interference with movement or stiffness in the affected part. At last local symptoms become evident and when the pus has arrived near the surface. It is become similar to a superficial abscess. It causes serious interference with function of organs. A) Superficial abscess: It is characterized by the symptoms of acute inflammation. Afterwards the center of the swelling becomes gradually softer, while periphery remains firm.

 Evacuation of contents is followed by thorough flushing with an antiseptic solution (10% povidone iodine).  Necrotic tissue should be removal with the fingers or a curette.  Tincture of iodine or other irritant antiseptic solution is indication as a dressing for the interior of the cavity to promote inflammation and consequent granulation and cicatrisation.  Antibiotic therapy should be given for 7-10 days after draining. Treatment of an acute abscess:  Measures to hasten the maturation of the abscess.  Opening the abscess with a bladed knife.

2) Cold or chronic abscess: It shows little or no inflammatory reaction. They develop slowly, are painless or slightly painful, and persist for a long time as indurate or cystic swellings. Sometimes they gradually undergo softening, and eventually burst by ulcerating the skin or mucous membrane which covers them. It may also be classified as: A.Hard cold abscess: Is surrounded by hard fibrous tissue and may contain only a small amount of pus. B.Soft cold abscess: It has a thin wall, and contains a comparatively large quantity of pus.

Treatment of a chronic abscess: The irritant ointments may be applied to render the abscess acute and bring the pus nearer to the surface before opining it. The treatment is on the same lines as that of an acute abscess. Differential Diagnosis of Abscess: 1) A cyst: whose formation is slower than that of an abscess, is devoid of inflammatory symptoms, fluctuates uniformly throughout, and is not hard at its periphery. 2) An inflamed and distended synovial bursa: This is recognized by its situation and by careful examination.

3) A hematoma: which is formed of coagulated blood and serum, feels somewhat doughy on palpation, may crepitate on pressure, and forms almost immediately after the receipt of an injury. It is not so tense or painful, and dose not point like an abscess. 4) An abdominal hernia: A recent traumatic hernia shows acute inflammatory symptoms which associated with the hernial swelling, simulate those of an abscess but careful examination will generally reveal the diagnostic features of a hernia. Note: In any case of doubt an exploratory puncture may be made with an exploring needle.