In Patient_2, bortezomib was discontinued in October 2017 since she had reached partial response with decrease of the monoclonal component. Nine months later, biochemical progression and new bone lesions, with 18% of plasma cells in the bone marrow aspirate, prompted her hematologists to consider starting another proteasome inhibitor. Although no previous reports on tolerance to alternative proteasome inhibitor in patients with a history of severe skin reactions to bortezomib had been published, we set out to try carfilzomib (KYPROLIS ® , Amgen Inc., Thousand Oaks, CA, USA), since its molecular structure was different enough to predict a low level of cross-reactivity. SPT (2 mg/mL) and IDT (0.2 mg/mL) to carfilzomib were negative both at immediate and delayed reading. A controlled intravenous challenge with carfilzomib (20 mg/m 2 ) was performed in a hospital setting in July 2018, with good tolerance. The patient received two more cycles without any side effects.Here, we present two new cases of confirmed delayed hypersensitivity to bortezomib with positive late-reading intradermal tests that suggest an underlying T-cell mechanism. To our knowledge, this is the first report of a desensitization schedule to bortezomib and the first evidence that carfilzomib is well tolerated and can be considered as a safe alternative in patients with delayed hypersensitivity to bortezomib. CONF LICTS OF INTERESTThe authors declare that they have no conflicts of interest.In our experience, negative cases occurred mainly in users, without fingertip affectation and with more facial and leg involvement. The final predominant diagnosis was irritant hand dermatitis whichshould be always reached after ruling out sensitization to acrylates.As conclusions, our study confirms a prehensile pattern in patients who apply the substance (professionals or "do it yourself" users) and a different clinical location of lesions in negative patch tested patients. We highlight the limitation in work ability created in our patients which in many cases required a definitive change of job, and the potential sensitization to acrylates in general population, specially when these substances are self-applied by the user. CONF LICTS OF INTERESTThe authors declare that they have no conflicts of interest.

Background Methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) contact dermatitis is a severe problem. The high concentrations of these substances and other isothiazolinones such as benzisothiazolinone (BIT) and octylisothiazolinone (OIT) contained in cleaning products may cause allergic contact dermatitis in sensitized patients. Objectives To evaluate the exposure to isothiazolinones contained in cleaning products on the market and from sensitized patients, and to verify the accuracy of labeling. Methods A total of 34 cleaning products were collected (17 supplied by sensitized patients and 17 bought randomly). Analysis was made of the concentrations of MI, MCI, BIT, and OIT using liquid chromatography tandem mass spectrometry (LC‐MS/MS). Results MI and BIT were the components most frequently detected. Of all the products analyzed, 76.5% contained at least one isothiazolinone. Twelve products had an MI concentration above the permitted level for rinse‐off cosmetics. Most of them were coming into direct contact with the skin in daily use. Mislabeling occurred in eight products. Conclusions Some cleaning products with high concentrations of isothiazolinones may cause cutaneous symptoms in sensitized patients, especially in spray form. The labeling should be correct, also regarding the use of each article.

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT) represents approximately 20% of cutaneous B lymphomas with an intermediate prognosis. Spontaneous regression is uncommon; there are only 2 published cases. An 83-year-old woman presented 2 orange erythematous nodules on the back of her right leg with an elastic consistency, infiltrated, painful to the touch, and of an 8-month evolution. A histological examination revealed a dense cellular dermo-hypodermic infiltrate sparing the papillary dermis, composed of large cells with immunoblast and centroblast morphology and frequent mitosis. Immunohistochemical studies showed positivity for CD20, CD79, Bcl2, Bcl6, MUM1, Fox-P1, and IgM with Ki67 >95%. Rearrangement of heavy IgH chains was monoclonal. The extension study was negative, establishing a diagnosis of PCDLBCL-LT, T2aN0M0. Three months after biopsy, the patient's lesions regressed spontaneously. New biopsies were taken that revealed a mild diffused dermo-hypodermic cellular infiltrate compounded by small-sized T lymphocytes, with predominance of CD8. Despite its self-limited character, treatment with radiotherapy was done, remaining asymptomatic after 1 year follow-up. There are 2 published cases of PCDLBCL-LT with spontaneous regression. The cause of this unusual autoinvolutional phenomenon is unknown; it may be an immune response against tumor cells through a traumatic or infectious mechanism.

Occupational sensitization to MCI/MI in cleaning professionals is worryingly increasing. This, in turn, could possibly account for many cases of cosmetics-associated contact dermatitis. Our findings suggest that a review of the regulations with regard to isothiazolinone concentrations in industrial and household detergents is necessary.