Pruritic Hyperkeratotic Papules on the Legs of a Patient with Atopic Dermatitis
Am Fam Physician. 2020 Jun 1;101(11):689-690.
A 36-year-old man presented with an intensely pruritic rash on both lower legs that had been present for three years. He had a history of asthma and moderate atopic dermatitis since childhood. The rash coincided with progressive worsening of his atopic dermatitis. It was associated with generalized pruritus that caused him to scratch, especially on his lower legs where the eruption was most intense. Physical examination revealed multiple hyperkeratotic papules on the lower limbs, particularly the pretibial areas (Figure 1).
Based on the patient's history and physical examination findings, which one of the following is the most likely diagnosis?
A. Lichen amyloidosis.
B. Lichen planus hypertrophicus.
C. Lichen simplex chronicus.
D. Pretibial myxedema.
E. Prurigo nodularis.
The answer is A: lichen amyloidosis. Primary localized cutaneous amyloidosis is a chronic pruritic skin disorder characterized by amyloid deposition in the dermis without systemic involvement. It is most prevalent in Southeast Asia and South America.1,2 Lichen amyloidosis is a subtype that mainly affects middle-aged adults, especially men with darker skin. It is characterized by a chronic pruritic eruption of multiple discrete, hyperkeratotic papules located predominantly on the shins in a symmetrical distribution.
Although the diagnosis of lichen amyloidosis is usually made clinically, histopathology characteristically shows deposits of hyaline material in the papillary dermis corresponding to amyloid, with positive results on Congo red testing. Most cases are idiopathic, but lichen amyloidosis may be associated with multiple endocrine neoplasia type 2A, atopic dermatitis, and autoimmune
Referencesshow all references
1. Lee DD, Huang CK, Ko PC, et al. Association of primary cutaneous amyloidosis with atopic dermatitis: a nationwide population-based study in Taiwan. Br J Dermatol. 2011;164(1):148–153....
2. Chia B, Tan A, Tey HL. Primary localized cutaneous amyloidosis: association with atopic dermatitis. J Eur Acad Dermatol Venereol. 2014;28(6):810–813.
3. Oiso N, Yudate T, Kawara S, et al. Successful treatment of lichen amyloidosis associated with atopic dermatitis using a combination of narrowband ultraviolet B phototherapy, topical corticosteroids and an antihistamine. Clin Exp Dermatol. 2009;34(8):e833–e836.
4. Linhardt PW, Walling AD. Prurigo nodularis. J Fam Pract. 1993;37(5):495–498.
This series is coordinated by John E. Delzell Jr., MD, MSPH, associate medical editor.
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