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Miscellaneous dermatology

Heat and cold key points test

Perniosis: #! Erythematous plaques that persist for several weeks #! May be presenting sign of systemic sclerosis # Can result in anaphylactoid symptoms #! Attacks follow exposure to cold Explanation: Perniosis or chilblains present during the winter months as violaceous or erythematous plaques on the digits that persist for several weeks. Perniosis is more common in those with connective tissue diseases especially systemic sclerosis and lupus erythematosus. Raynaud’s phenomenon: # Erythematous plaques that persist for several weeks #! May be presenting sign of systemic sclerosis # Can result in anaphylactoid symptoms #! Attacks follow exposure to cold Explanation: Raynaud’s phenomenon follows exposure of the digits to cold. They become white then, during warming, cyanosed and erythematous before returning to normal colour. Secondary Raynaud’s is associated with connective tissue diseases, especially systemic sclerosis. Cold urticaria: # Erythematous plaques that persist for several weeks # May be presenting sign of systemic sclerosis #! Can result in anaphylactoid symptoms #! Attacks follow exposure to cold Explanation: Cold urticaria results in wealing for up to an hour following exposure to cold. Widespread wealing can result in anaphylactoid symptoms. Erythema ab igne: *! Often followed by postinflammatory pigmentation * Associated with polycythaemia and thrombocythaemia * Related to eccrine secretion * May be treated with botulinum toxin Explanation: Erythema ab igne is due to local heat injury and may affect normal skin. Affected skin is at first erythematous in a vascular distribution but within a few days becomes pigmented. Erythromelalgia; * Often followed by postinflammatory pigmentation *! Associated with polycythaemia and thrombocythaemia * Related to eccrine secretion * May be treated with botulinum toxin Explanation: Erythromelalgia is burning pain on warming the hands and feet, which appear erythematous or cyanotic. Some cases have underlying polycythaemia or thrombocythaemia. Low-dose aspirin may be helpful. Cholinergic urticaria: * Often followed by postinflammatory pigmentation * Associated with polycythaemia and thrombocythaemia *! Related to eccrine secretion * May be treated with botulinum toxin Explanation: Cholinergic urticaria causes wealing for 15 to 60 minutes and is provoked by heat, emotional stress and exercise. It is usually related to eccrine sweating. Hyperhidrosis: # Often followed by postinflammatory pigmentation # Associated with polycythaemia and thrombocythaemia #! Related to eccrine secretion #! May be treated with botulinum toxin Explanation: Hyperhidrosis is excessive generalised or localised eccrine sweating and is rarely due to hyperthyroidism or hypothalamic disease. It is aggravated by thermal, emotional or gustatory stimulae. It may be treated with antiperspirants, iontopheresis, oral probantheline or beta blockers, intradermal botulinum toxin and in disabling cases by sympathectomy. Miliaria is characterised by * Often followed by postinflammatory pigmentation * Associated with polycythaemia and thrombocythaemia *! Caused by eccrine secretion * May be treated with botulinum toxin Explanation: Miliaria (sweat rash) presents as irritable non-follicular papules, vesicles or pustules most often on the trunk. It is managed by cooling the skin.