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                  Classification of Soft Tissue Tumour

 
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Bacteria form part of the normal resident flora of the skin. In certain conditions these are of pathogenic importance. Visit: Cutaneous Infections and Infestations

Superficial pyogenic infection (pyodermas): These are usually caused by staphylococcus aureus and strains of Streptococcus.  These are usually characterized by a dense acute inflammatory infiltrate. Hair follicles may also be infected causing folliculitis.

Staphylococcal Infection

Impetigo

Staphylococcal scalded skin syndrome

Toxic Shock Syndrome

Streptococcal Infection

Cornybacterial Infections: Biopsy may appear normal. The lesion is usually limited to the stratum corneum.

Diphtheria

Erythrasma: Locatd in skin folds. This is an example of " invisible dermatosis". Caused by diptheroid bacilli, Cornybacterium minutissimum. Special stain : Small coccobacillli are demonstrated by Gram , PAS and methenamine silver preparations.

Pitted keratolysis : Often located on the plantar surface of the feet. Pits appear as multiple crateriform defect in the stratum corneum. Filamentous and coccoid organisms are demonstrated by Gram and methenamine silver stain.

Mycobacterial Infection:

Tuberculosis

Mycobacterium ulcerans Infection (Buruli Ulcer)

Mycobacterium marinum infection

Leprosy

Chlamydial Infection 

Psittacosis

Lymphogranuloma Venereum

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Deep pyogenic Infection (Cellulitis): Cellulitis is a diffuse inflammation of the connective tissue of the skin and deeper soft tissue.

Erysipelas: Form of cellulitis. Subepidermal edema with formation of vesiculobullous lesion. There may be a dense diffuse neutrophilic infiltrate and in some cases vascular and lymphatic dilatation.

Necrotizing fasciitis: (Flesh eating bacteria). Rare form of cellulitis, usually located on the leg. It progresses to necrosis of skin and underlying tissues and may spread into the underlying muscle. Histologicallly there isnecrosis of the epidermis, dermis and upper subcutis. There is septic vasculitis with inflammation of the vessel wall. Thrombi may be present in the lumen.

Clostridial myonecrosis (Gas gangrene)

Blastomycosis-like pyoderma

Neisserial Infections:

Meningococcal Infection

Gonococcal Infection

Miscellaneous bacterial infections:

Anthrax

Brucellosis

Yersiniosis

Granuloma Inguinale

Chancroid

Rhinoscleroma

Tularemia

Listeriosis

Cat Scratch Disease

Malakoplakia

Rickettsial Infection: Usually produces acute febrile illness together with headache and myalgia. Histologically, there is lymphocytic vasculitis and areas of coagulative necrosis of the epidermis and dermis.

Rocky Mountain Spotted Fever

Epidemic Typhus

Scrub Typhus

   

Further reading: Skin Pathology. 2nd ed. D Weedon Pg 618-637