Molecular mimicry: a true pathogenetic concept for T-cell-mediated autoimmune and reactive skin diseases?

Sweet's Syndrome (SS) in the Course of Acute Myeloid Leukaemia (AML)

Firstly described by Robert Douglas Sweet in 1964, febrile neutrophilic dermatosis is a disabling, not only cutaneous disorder, clinically characterised by fever and painful erythematous nodules, with a typical background of neutrophilia. Sweet’s syndrome (SS) is a chronic inflammatory reactive disorder of unknown cause and incompletely established pathogenesis, although an interplay between genetic and environmental factors, including infections, is likely to occur. A significant part of cases has been demonstrated to be linked with malignancies, especially in the hematologic setting. Because of the underlying disease and related therapeutic measures, SS may present atypical clinical course, whereas the response to treatment is strictly dependent on the concurrent hematologic disease. Herein we describe a case of a lady who had a refractory form of SS, resulted in a paraneoplastic cutaneous disease, and AML. Surprisingly, clinical remission of SS followed cytotoxic chemotherapy while hematologic disorder obtained a further complete response.

Lateralized exanthem mimicking figurate inflammatory dermatosis of infancy after methimazole therapy

We reported a case of an 11-year-old girl admitted to our hospital for goiter, tachycardia, sweating, and visible and palpable thyroid. Thyroid function tests revealed a low thyrotropin level (<0.004 mIU/L) and elevated free thyroxine level (3.4 ng/ dL) diagnosed with Graves' disease and treated with methimazole. This anti-thyroid drug is recommended as first-line treatment in children with Graves' disease because it produces minor adverse effects with respect to propylthiouracil. She developed a lateralized exanthem mimicking figurate inflammatory dermatosis of infancy after methimazole therapy. The symptoms resolved after discontinuation of methimazole and treatment with an antihistamine and a corticosteroid. Furthermore, the treatment was changed to propylthiouracil without any adverse effects. According to current literature this is the first case of cutaneous figurate erythema related to methimazole, different from other well-known reactions such as skin eruption or urticaria.