Atopic dermatitis (AD) and psoriasis are common skin diseases in which dysfunction of the epidermal barrier leads to skin inflammation and altered expression of proinflammatory cytokines.1 There often is overlap in the clinical and histopathologic features of AD and psoriasis, which can make diagnosis a challenge. Persistent late-stage AD can present with psoriasiform lichenified changes, and psoriasis lesions in the acute stage can have an eczematous appearance.2 Histologically, chronic psoriasis lesions share many overlapping features with AD, and some subsets of AD with IL-17 predominance (ie, intrinsic, pediatric, presentation in Asian patients) exhibit a psoriasiform appearance.3,4
Atopic dermatitis and psoriasis are considered 2 distinct conditions because AD is a helper T cell (TH2)–driven disease with subsequent overproduction of IL-4 and IL-13 and psoriasis is a TH17 cell–driven disease with overproduction of IL-173; however, the shared features of AD and psoriasis represent an underlying immunopathological spectrum2,5,6 in which one condition can develop following treatment of the other condition (immunological shift in pathways), both conditions can occur at different times in a patient’s life with alternating cycles of disease flares, or both conditions can coexist as an overlapping syndrome.1,2 A retrospective study from 2012 to 2019 estimated the prevalence of concomitant AD and psoriasis in the United States at 1.3%, with AD following the diagnosis of psoriasis in 67% of cases.1 Concurrent AD and psoriasis—when both diseases flaresimultaneously—is the rarest scenario.2,5
Treatment modalities for AD include topical corticosteroids, which act on immune cells to suppress the release of proinflammatory cytokines, as well as dupilumab, which offers targeted blockade of involved cytokines IL-4 and IL-13. Psoriasis can be treated with multiple immune modulators, including topical corticosteroids and vitamin D analogs, as well as systemic medications that reduce T-cell activation and inflammatory cytokines through targeting of IFN-γ, IL-2, tumor necrosis factor α, IL-17, and IL-23.7,8
We present the case of a patient with long-standing concurrent, treatment-resistant AD and psoriasis who was successfully treated with dual biologic therapy with guselkumab and dupilumab.
A 62-year-old woman presented to our dermatology clinic with red itchy scales and painful fissures on the palms, hands, and soles of more than 12 years’ duration. Her medical history included an allergy to amoxicillin-clavulanate as well as an allergy to both dog and cat dander on prick testing. Her family history included dyshidrotic eczema in her mother. A complete blood cell count with differential was within reference range. A shave biopsy of the right dorsal hand performed at the onset of symptoms at an outside facility revealed hyperkeratotic acanthotic epidermis with a mild perivascular lymphocytic infiltrate.
Results of patch testing indicated contact hypersensitivity to the botanical rosin colophonium (or colophony); carba mix (1, 3-diphenylguanidine, zinc dibutyldithiocarbamate, and zinc diethydithiocarbamate); thiuram mix (tetramethylthiuram disulfide, tetramethylthiuram monosulfide, and tetraethylthiuram disulfide); n,n-diphenylguanidine; and tixocortol-21-pivalate. Our patient was given guidance on avoiding these agents, as it was suspected that exposure may be exacerbating the psoriasis. The psoriasis was treated with topical corticosteroids, keratolytics, and calcineurin inhibitors, all of which offered minimal or no relief. Trials of systemic agents, including methotrexate (discontinued because transaminitis developed), etanercept, adalimumab, and apremilast for 6 to 10 months did not provide improvement.
Two years prior to the current presentation, our patient had been treated with the IL-23 inhibitor guselkumab, which provided moderate improvement. When she presented to our clinic, physical examination while she was taking guselkumab demonstrated prurigo with excoriations of the extremities, hyperkeratosis with scaling and fissures of the soles, erythematous scaly plaques on the palms and dorsal surface of the hands, and mild onycholysis of the nails (Figures 1 and 2). Because we were concerned about concomitant intrinsic AD, dupilumab was initiated in conjunction with guselkumab. A second biopsy was considered but deferred in favor of clinical monitoring.