Imiquimod-induced widespread psoriasi-form eruptions

Rare Cutaneous Side Effects of Imiquimod: A Review on Its Mechanisms, Diagnosis, and Management

“…The histopathological features of imiquimod-induced or imiquimod-exacerbated psoriasis are largely consistent with those of classic psoriasis, e.g., parakeratosis, focal granular layer loss, acanthosis, occasional Munro microabscesses, and perivascular infiltration of lymphocytes in the upper dermis [ 13 , 54 , 55 , 60 ]. Although dermal eosinophil infiltration and lichenoid patterns are considered to be clues to the diagnosis of drug-induced psoriasis [ 53 ], they were found in only one patient [ 55 ].…”

“…We retrieved ten cases described as imiquimod-induced or imiquimod-exacerbated psoriasis (summarized in Table 1 ), which has been reported following treatment of AK [ 54 , 55 ], BCC [ 56 ], and condyloma acuminatum [ 57 ] in adults and the off-label treatment of molluscum contagiosum and verruca plana in children [ 58 ]. The reported cases included three males, six females, and one whose sex was not mentioned.…”

“…One patient developed fingernail abnormalities, which manifested as onychodystrophy, oil spots, and longitudinal ridging [ 56 ]. Only two patients were reported to suffer from pruritus, which is an important symptom in classic psoriasis [ 54 , 56 ].…”

“…Most patients responded well to topical treatment with corticosteroid ointment and/or calcipotriol cream and narrowband ultraviolet B phototherapy (NB-UVB) [ 13 , 26 , 54 , 56 , 58 , 60 ]. In one patient, the eruptions resolved spontaneously without any treatment after 4 weeks [ 26 ].…”

“…Furthermore, Tsutsumi et al [ 55 ] reported a case of imiquimod-induced psoriasis in which the eruptions resolved with a decrease in TNF-α levels after infliximab treatment, indicating that TNF-α also plays an important role in psoriasis associated with imiquimod. In addition, the levels of mast cells, which release various cytokines that trigger psoriasis, can be increased in lesions after the use of topical imiquimod [ 54 , 61 ]. Furthermore, the exacerbation of preexisting psoriasis may be partly attributed to the tissue-resident memory T cells [ 57 ].…”