Case of pityriasis rubra pilaris progressed to generalized erythroderma following blockade of interleukin-17A, but improved after blockade of interleukin-12/23 p40.

We report herein a case of a 72-year-old man with pityriasis rubra pilaris (PRP) that was refractory to conventional therapies. His skin lesions progressed to generalized erythroderma despite anti-interleukin (IL)-17A antibody therapy. Topical corticosteroids, emollients, systemic retinoid, methotrexate, cyclosporin and phototherapy yielded no therapeutic response. However, blockade of IL-12/23 p40 dramatically improved his cutaneous lesions. Complete remission was achieved 4 weeks after the first injection of ustekinumab and maintained for more than 48 weeks. Our data indicate that IL-12 was associated with the onset of PRP in this patient, rather than IL-23. IL-12 is critical for the differentiation of T-helper (Th)1 cells. Thus, the Th1 pathway may be associated with the onset of PRP.

Generalized leukaemia cutis from a small cell variant of T-cell prolymphocytic leukaemia presenting with exfoliative dermatitis.

T-cell prolymphocytic leukaemia (T-PLL) is a rare, aggressive neoplasm of mature T lymphocytes. The small cell variant occurs in approximately 20% of T-PLL patients. The skin findings of leukaemia consist of leukaemia-specific skin lesions, which are infiltrated by leukaemia cells, and non-specific lesions. The former type of lesion signifies leukaemia cutis. Leukaemia cutis presents clinically as tumours, nodules, or patches on the scalp, face and trunk. We report here an 82-year-old Korean male patient who presented with erythema, erosion, vesicles, and scales on his entire body with no clear underlying cause. He had been treated with oral retinoids, steroids, and phototherapy for the diagnoses of drug eruption, pityriasis rubra pilaris, and exfoliative dermatitis at other hospitals. We suspected a hidden malignancy and diagnosed small cell variant T-PLL through blood and bone marrow examination. A skin biopsy specimen showed dense infiltration of small lymphocytes in the dermis. Most of the atypical lymphocytes stained positively with CD markers such as CD2, CD3, CD4, CD5, CD7 and CD8, thereby confirming the presence of leukaemia cells. To our knowledge, this is the first case of generalized leukaemia cutis from small cell variant of T-PLL presenting with exfoliative dermatitis over the whole body.