Clinical Skin

Question 1

Parakeratosis

Answer 1

• pathological
• Thickened keratin layer
• Keratins contains spindly nuclear remnants
• usually associated with loss or severe thinning of underlying granular layer
• may be associated with epidermal dysplasia

Question 2

Hyperkeratosis

Answer 2

• (non-pathological)
• present in elbow & soles
• thickened keratin layer
• no histological abnormality in keratin layer
• usually associated with thickening of underlying granular layer - hypergranulosis
• seen in cases of chronic trauma like scratching

Question 3

Pemphigus vulgaris

Answer 3

• blistering disorder
• auto-AB that result in dissolution of intercell attachments (desmosomes) w/in epidermis & mucosal epithelium
• Clinical presentation:
  
  • superficial blisters & bullae that rupture easily
  • ulcerated blisters in oral mucosa are also common
• Light microscope shows:
  
  • tombstone blister
  • Acantholysis: disruption of intercell adhesions in cells immediately above basal layer in stratum spinosum
  • suprabasal blister
  • acantholytic cells: rounded & lose symmetry
  • fish-net patter of Ig deposition along plasma membrane of epidermal keratinocytes

Question 4

Bullous pemphigoid

Answer 4

• chronic autoimmune disorder
• bullous pemphigoid antigens 1 & 2 present as nl constituents of hemidesmosomes -> auto-ab bind to antigens & stimulate complement deposition & leucocyte infiltration -> degrading eosinophils release proteases that degrade hemidesmosomes
• Rx: topical Corticosteroid

Question 5

Acne vulgaris

Answer 5

• occurs almost universally in middle to late teenage years
• hormonal variations & alterations in hair follicles, particularly in sebaceous glands
• Open Comedone (black head): small follicular papules with central keratin plug
• Severe acne: papules, nodules, cysts
• Light microscope:
  
  • development of keratin plug blocking outflow of sebum
  • hypertrophy of sebaceous gland
  • infection with cane causing bacteria Propionobacter acnes
  • inflammation of follicle
• Rx: Vitamin A

Question 6

Vitiligo

Answer 6

• depigmentation disorder
• auto-immune
• destruction of melanocytes
• Types: focal, segmental, generalized
• Rx:
  
  • Medical: topical steroid therapy, psolaren photochemotherapy (increases pigmentation), depigmentation
  • surgical: autologous skin graft, micropigmentation, melanocyte transplants

Question 7

Psoriasis

Answer 7

• due to increased rate of proliferation of mitotic cells, thereby leading thickened epidermis
• leads to shedding of epidermis constantly, resulting in scales seen as whitish patches, especially in extensor aspects of limbs, trunk & lumbosacral region
• autoimmune T-cells (cytokines & cell-mediated autoimmunity)
• increased epidermal turnover (3-5 d); marked epidermal thickening and increase in size of epidermal ridges
• abnormal keratinocyte differentiation: loss of S. granulosum
• parakeratosis: S. corneum thickening & nuclei retention
• weak junctional complexes in superficial layer (silvery scales)

Question 8

Basal Cell Carcinoma

Answer 8

• most common invasive cancer in humans
• arises from basal cells of epidermis or epidermal appendages
• tendency to occur in sun-exposed areas and in lightly pigmented people
  
  • pearly papules
  • contain prominent, dilated sub-epidermal blood vessels
  • rolled out margins
  • advanced lesions may ulcerate with extensive local invasion (rodent ulcers)
• nest of uniformly atypical basaloid cells within the dermis (basophilic)
• separated from adjacent stroma by thin clefts
• basophilic cells with dark staining nuclei and sparse cytoplasm
• cells at the periphery tend to be arranged radially with their long axes in parallel arrangement (pallisade arrangement

Question 9

Squamous Cell Carcinoma

Answer 9

• 2nd most common tumour arising in sun exposed sites
• higher incidence in men than women
• DNA damage induced by exposure to UV light
• p53 mutations
• commonly associated with chronic immunosuppression: chemotherapy or organ transplant
• increased susceptibility of keratinocytes to infection and transformation by oncogenic viruses
• other risk factors
  
  • industrial carcinogens like tars & oils
  • chronic ulcers
• light microscopy shows:
  
  • nodular & ulcerated lesions
    
    • well differentiated
    • highly keratising
    • larger than nl cells
    • nuclear pleomorphism: keratin pearls

Question 10

Malignant Melanoma

Answer 10

• malignant transformation of melanocytes
• most common on sun exposed surfaces
• lightly pigmented individuals are at higher risk
• important pre-disposing factors:
  
  • inherited genes: mutations in RB tumour supressor gene
  • sun exposure
• clinical features:
  
  • usually asymptomatic so frequently undetected; very dangerous
  • itching or pain may occur
  • changes in colour, size or shape of a pigmented lesion most important clinical indicator
    
    • A: assymetry
    • B: borders (irregular)
    • C: colour (variegated)
    • D: diameters (>6mm)
    • E: elevated lesion
  • Light microscopy shows:
    
    • ayptical melanocytes in epidermis & dermis with large nuclei & prominent nucleoli
    • radial growth: horizontal spread of melanoma within epidermis
    • vertical growth: tumour cells invade deeper layers
    • metastases may occur: usually fatal

Question 11

Neurofibromatosis (Von Reclinghausens Disease)

Answer 11

• not a skin lesion
• nerve-ending lesions