Eruptive pruritic papular porokeratosis

“Eruptive pruritic papular porokeratosis (EPPP)”, first proposed by Kanzaki in 1992 [1] and designated as “Inflammatory disseminated superficial porokeratosis (Inflammatory DSP)” by Tanaka in 1995 [2], is a special variant of porokeratosis. The typical clinical course consists of asymptomatic DSP for months to years, followed by the acute pruritic exacerbations, and then subsides spontaneously within 12 months [3]. Histopathological examination reveals the characteristic cornoid lamellae. This paper describes a typical case of EPPP in China and summarizes previously reported EPPP cases.
Herein we describe a typical case in China – a 68-year-old man with EPPP for 5 years. After the initial 3 years of asymptomatic DSP, typical eruptions such as annular lesions with a raised and sharply marginated keratotic border suddenly presented with recurrent multiple, pruritic, erythematous papules on his extremities and trunk. The lesions subsided in the winter and recurred in the summer. Physical examination revealed numerous nodular erythematous papules like prurigo nodularis lesions (Figure 1 A), and hyperpigmented brown macules on his trunk (Figure 1 B). The patient had a history of mild hypertension, no other relevant diseases and he was not on medication. Biopsy specimen of a reddish papule on his right upper limb did not show the granular layer and patchy parakeratosis of keratinocytes in the characteristic cornoid lamellae (Figure 1 C). Mild focal lymphocytes (without eosinophils) infiltrates around the blood vessels in upper dermis (Figure 1 D).
Based on the above symptoms, the patient was definitely diagnosed as EPPP. These pruritic papules did not respond well to topical steroids or oral antihistamines. Interestingly, as the winter progressed, the papules levelled off and the itching was reduced, leaving behind some brownish non-inflamed patches in the follow-up. By analysing 17 cases of EPPP including the one reported here, we found that EPPP might be manifested with the following characteristics (Table 1 [1–14]): (1) history of pre-existing porokeratosis varied from months (> 2 months) to several years except 1 patient who had no pre-existing lesions and no tendency to spontaneous resolution in a 16-month follow-up [4]; (2) less than half of patients had other pre-existing diseases or suspicious triggering factors, including cardiovascular disease, medication history, autoimmune disease, cancer or others; (3) elderly males might be the...


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