Answer to last month's Clinical Quiz

Question:
This 71 years old man complained of an itchy rash on the lower limbs for the past 25 years. The rash was symmetrically distributed over both lower limbs. It consisted of firm, discrete and slightly brownish papules evenly distributed on the extensor aspects of both lower limbs. He had used a variety of topical medications without much relief of symptoms. The pruritus could sometimes be severe. His past and current health was excellent. Investigations including complete blood picture, liver and renal function tests as well as urine examinations were all normal.

Answer: C. Lichen amyloidosus

Lichen amyloidosus is one form of primary localised cutaneous amyloidosis of unknown cause. It is particularly common in Chinese. It commonly presents as a persistent, pruritic papular eruption on the anterior shins though it may also be found on the extensor aspects of the thighs, forearms and upper arms. The individual lesions consist of multiple discrete papules which are scaly and pigmented. Papules may coalesce into thickened plaques which then can closely simulate hypertrophic lichen planus or chronic papular eczema. The condition persists for decades with localised pruritus as the main feature. Though the condition will not affect the general health, persistent pruritus can be troublesome. Treatment includes topical application of potent topical steroids with or without keratolytic agents. Dermabrasion has been used to treat the condition with some success. The typical location and morphology of the skin lesions can easily lead to a correct spot diagnosis by examination alone. Bowenoid papulosis is closely related to HPV-16 infection. Typically it is found on the shaft of penis. It will present itself as multiple papules grouped with a verrucous or smooth surface with brown red to black in colour. It needs to be differentiated from genital warts. Chronic papular eczema usually is found to have an ill defined margin for the plaques and papules. A pattern of disorderly lesions is found, the lesions are not monomorphic.