Drug-induced panniculitides.

A substantial number of all panniculitides fails to recognize a specific etiology, and that is true also for a relatively frequent type of panniculitis, such as erythema nodosum (EN). Between the recognized causative factors of panniculitides, infectious, physical agents, autoimmune mechanisms and neoplastic disorders are well known. On the contrary, the role of drugs as inducers of panniculitides is marginally considered, and their report limited to anecdotal observations, often without due histopathological support. Since the clinical and histopathological features of drug-induced panniculitides are indistinguishable from those caused by other agents, the causative relationship may be demonstrated by the history of previous drug intake and by clinical improvement after drug discontinuation. We reviewed the currently reported descriptions of drug-induced panniculitis, including a few exemplificative original observations. EN results as the most frequently reported drug-induced panniculitis. Among the causative drugs of EN a variety of medications, with disparate, or even opposite, mechanisms of action are reported, thus limiting the understanding of the pathogenesis. Common causative drugs include oral contraceptives, nonsteroidal anti-inflammatory drugs, antiobiotics and leukotriene-modifying agents. Unfortunately, in several cases, the diagnosis of drug-induced EN is done on clinical findings alone. In those cases, the lack of histopathological support does not allow to define a precise clinicopathological correlation on etiologic grounds. Drug-induced lobular and mixed panniculitides, including eosinophilic panniculitis, are even more rarely described. Reported causative agents are glatiramer acetate, interferon beta and heparin (at sites of injections), and systemic steroids, tyrosine kinase inhibitors and BRAF with subcutaneous fat involvement at distance. In view of the recent introduction of new classes of drugs, attention should be paid to disclose their possible etiologic role in inducing among other side effects, also panniculitides.

Histopathologic spectrum of Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS): a diagnosis that needs clinico-pathological correlation.

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) is characterized by an heterogeneous group of severe dermatologic manifestations and systemic involvement, due to several groups of medicaments. A series of 9 consecutive cases, observed from 2008 to 2013 in the Department of Dermatology, University of Pavia, is reported, all satisfying the clinical, hematological and systemic diagnostic criteria of DRESS. Clinically, 4 out of 9 patients had an urticarial and papular eruption, 2 an erythema-multiforme-like (EM-like) pattern, 2 erythroderma and 1 had an erythematous and macular reaction. Aim of the study was to describe the histopathologic features of DRESS and to trace a possible correlation between the four clinical recognized types of the syndrome and the histopathological patterns. Predominantly, a superficial perivascular lymphocytic infiltrate, extravasation of erythrocytes, and focal interface changes characterized DRESS cases. Less frequently, histopathology revealed the presence of necrotic keratinocytes; surprisingly, only in 2 cases the presence of rare dermal eosinophils was detected, even if all the patients had significant peripheral eosinophilia. A histopathological diagnosis of DRESS seems per se, according to our data, not feasible, since the main histopathological changes (interface changes, superficial perivascular dermatitis, focal spongiosis, lichenoid infiltrate, rare presence of necrotic keratinocytes) can be interpreted generically as a drug induced dermatitis. The above mentioned histopathological changes, however, when associated with clinical information on cutaneous and systemic involvement of the patient, allow the pathologist or the dermatopathologist to make a diagnosis of DRESS with a reliable margin of certainty.