Drug-induced psoriasis Palmoplantar psoriasiform rash associated with letrozole hormone therapySymptoms/signs59-year-old female patient.The patient reports the gradual onset of scaly, thickened lesions of the hands about a month after starting hormonal therapy. The lesions are associated with itching and mild pain.Patient photographs Clinical presentationA physical examination of the skin revealed erythematous plaques with prominent scaling and fissure formation on the palmar surface of both hands and with symmetric distribution. Erythema of the proximal nail fold is associated with the disappearance of the cuticle. In this case, nail changes are suggestive of the diagnosis and consist of distal onycholysis and subungual hyperkeratosis associated with psoriasis.Medical historyIn September 2020, she was diagnosed with a right breast tumour, for which she underwent surgery in the same month to remove the upper inner quadrant of her right breast, followed by a course of adjuvant radiotherapy (16 sessions of 2.5 Gy for a total of 40 Gy). Simultaneously, in October 2020, she was undergoing therapy with letrozole, an aromatase inhibitor.Differential diagnosis Drug-induced psoriasi Koebner phenomenon secondary to another drug-induced skin reaction Chronic eczematous dermatitis of the hands Paraneoplastic acrokeratosis Acquired keratodermaDiagnostic testsExamination of the entire skin area and nail appendages is necessary to identify other signs supporting the clinical diagnosis. The observation of a clear demarcation at the edge of lesions is typical of psoriasis rather than eczematous dermatitis, while both diagnoses are associated with fissures and exacerbation following trauma. In paraneoplastic acrokeratosis, psoriasiform lesions on the extremities take on a purplish hue and are associated with onychodystrophy. Finally, acquired keratoderma is a common form that mainly affects the soles of the feet with less involvement of the hands. Psoriasiform lesions that occur in areas previously affected by a drug-induced skin reaction may be indicative of the Koebner phenomenon.Description of the diseaseThe introduction of drugs can be associated with psoriasis according to four mechanisms: onset of psoriasis; appearance of new lesions in a person with psoriasis; worsening of existing lesions; development of therapeutic resistance. Psoriasiform eruptions affecting the hands and feet can be persistent and resistant to specific therapies.Pharmacological treatment and patient instructionsDue to the hyperkeratotic nature of the lesions, first-line treatment involves topical corticosteroids in combination with a keratolytic agent. An ointment containing 0.05% betamethasone dipropionate + 3% salicylic acid was therefore prescribed, to be applied to the hands with an occlusive dressing in the evening for 4 weeks.Dermocosmetic management CICAPLAST Baume B5+, a repairing and soothing balm that rebalances the skin’s microbiome, to be applied locally in the evening, preferably with an occlusive cotton glove dressingFollow-up (adjuvant treatment outcomes)Clinical re-evaluation after 4 weeks showed a reduction in dryness and fissures, but stability of erythema. The use of narrowband UVB phototherapy is therefore indicated (2 weekly sessions for 9 weeks with an initial dose of UVB of 0.39 J/cm2).
