Scaly skin diseases
Disorders of keratinisation key points test
Lichenoid histology refers to:
#! Liquefaction degeneration of basal layer
# Thickened projections of epidermis
#! Dermal infiltration of inflammatory cells hugging the basal layer
Explanation: Lichenoid histology refers to liquefaction degeneration of basal layer, dermal infiltration of inflammatory cells hugging the basal layer, colloid bodies and dermal melanin. The epidermis may or may not be thickened. Spongiosis is characteristic of eczema.
Idiopathic lichen planus is associated with:
# Renal disease
#! Polygonal papules and plaques on ventral wrists, forearms and legs
#! White lacy marks or painful erosions on mucosal surfaces
# Keratoderma of palms and soles
Explanation: Lichen planus is characterized by polygonal papules and plaques on cutaneous surfaces and white lacy marks or painful erosions on mucosal surfaces. Some patients with lichen planus have hepatic disease, Diffuse keratoderma is not a feature of lichen planus although firm palmoplantar papules may be present.
Causes of lichenoid drug eruption include:
#! ACE inhibitors
Explanation: Lichenoid drug eruptions are characteristically diffuse, with scattered dry irritable plaques and characteristic lichenoid histology. They are uncommon and may be due to a large number of drugs although ACE inhibitors, thiazides, anti-malarials and gold are most frequently responsible. Retinoids are sometimes used to treat lichenoid disorders. Digoxin rarely causes adverse cutaneous effects.
# Is the most likely reason for vulval itching in children
#! May present as dry white plaques on the shoulders
#! Is more common in females than in males
#! In genital areas predisposes to squamous cell carcinoma
Explanation: Lichen sclerosus most often presents as a cause of vulval pruritus in postmenopausal females and is an uncommon cause in children. It may cause white plaques on other areas of the body, most often shoulders, breasts, buttocks and thighs. It is a cause of invasive squamous cell carcinoma of genital mucosa.
#! May be due to mutations in genes coding for keratin
#! May be associated with steroid sulphatase deficiency
# Should be treated with topical steroid creams
# May be a complication of acute alcoholic poisoning
Explanation: There are a variety of genetic types of ichthyosis in which coding for keratin protein is faulty. X-linked recessive ichthyosis is associated with deficiency of steroid sulphatase. Ichthyosis is treated with emollients. Topical steroids should be used to treat inflammatory skin diseases particularly eczema. Acquired ichthyosis may be seen as a complication of cachexia and excessive ingestion of kava.