Skin Infections (Bacterial, Fungal, Parasitic) Pathology Notes PDF

PATHOLOGY 09/07/2024. MOD 5: SKIN INFECTIONS (BACTERIAL, FUNGA...

PATHOLOGY 09/07/2024. MOD 5: SKIN INFECTIONS (BACTERIAL, FUNGAL, PARASITIC) Dr. Rennan B. Navarro, M.D. Trans Group/s: 1B PART 2A: COMMON SKIN INFECTIONS 1 Lesions start as erythematous macules. I. INTRODUCTION 2 It eventually creates subcorneal pustules (multiple small pustules rapidly supervene). DEFINITION OF TERMS 3 As pustules break, shallow erosions form. Shallow erosions are covered with drying Skin infection Infection of the skin caused by a serum giving a characteristic clinical pathogen appearance of honey-colored crust. Dermatitis Inflammation of the skin If the crust is not removed, new lesions form about the Infective Inflammation of the skin caused by an periphery, extensive epidermal damage may ensue. dermatitis infection The clinical appearance of a skin disease depends on the: ○ Site within the skin ○ Nature of the organism ○ Nature of the body’s response to the organism. The skin gets involved with infection following two main routes: ○ Internally via the bloodstream (hematogenous) as in the case of disseminated tuberculosis. ○ Externally by penetrating the skin barrier such as in the case of Schistosoma wherein the cercariae Impetigo; honey-colored crust (arrow). penetrates the skin. 1. HISTOPATHOLOGY (IMPETIGO) II. BACTERIAL SKIN INFECTIONS Characteristic finding in impetigo is the accumulation of Common skin infections caused by bacteria include: neutrophils (PMNs) beneath the stratum corneum, called subcorneal pustules 1 Impetigo Rupture of pustules results in superficial layering of serum, neutrophils, and cellular debris to form the characteristic honey-colored crust 2 Furuncle ○ Crust: a collection of serum, neutrophils (PMNs) and debris 3 Carbuncle 4 Staphylococcal Scalded Skin Syndrome (SSSS) 5 Mycobacteria (Leprosy and Tuberculosis) A. IMPETIGO Caused by Group A-beta hemolytic Streptococci and Staphylococcus aureus (most common cause) Exist in two forms: ○ Impetigo contagiosa (nonbullous impetigo) – caused by Streptococcus ○ Impetigo bullosa – caused by Staphylococcus aureus; mainly seen in children; lesions are bigger in size Involves exposed skin (face and hands); highly contagious Characteristic gross finding: honey-colored crust Characteristic histologic finding: subcorneal pustules Subcorneal Pustule. STAGES OF IMPETIGO Pathology - Mod 5 Skin Infections (Bacterial, Fungal, Parasitic) 1 of 8 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. 2. PATHOGENESIS (IMPETIGO) Size Smaller Bigger Blister formation is related to production of a toxin that specifically cleaves the desmoglein 1 molecule responsible for cell-to-cell adhesion within the Draining sinus Usually single Multiple uppermost epidermal layers. Deeper; to the point B. FURUNCLE Degree of that it can cause Also known as boil skin Superficial; cellulitis and A focal suppurative inflammation of the skin and laterally spreading* involvement osteomyelitis as subcutaneous tissue. complications Has a recurrent behavior and can occur as either solitary or multiple lesions Common in moist, hairy areas (e.g. face, axilla, groin, D. STAPHYLOCOCCAL SCALDED SKIN SYNDROME legs and submammary folds). (SSSS) / RITTER’S DISEASE Main etiologic agent is the Staphylococcus aureus Skin infection that is toxin-mediated (exfoliative A & B Infection begins in a single hair follicle that eventually toxins) becomes an abscess, causing thinning and rupture of ○ These toxins cause exfoliative dermatitis, which the overlying skin frequently occurs in children (newborn and