Drug-induced skin reactions: a pathologist viewpoint

Immunological Mechanisms in Cutaneous Adverse Drug Reactions

Adverse drug reactions (ADRs) are an inherent aspect of drug use. While approximately 80% of ADRs are predictable, immune system-mediated ADRs, often unpredictable, are a noteworthy subset. Skin-related ADRs, in particular, are frequently unpredictable. However, the wide spectrum of skin manifestations poses a formidable diagnostic challenge. Comprehending the pathomechanisms underlying ADRs is essential for accurate diagnosis and effective management. The skin, being an active immune organ, plays a pivotal role in ADRs, although the precise cutaneous immunological mechanisms remain elusive. Fortunately, clinical manifestations of skin-related ADRs, irrespective of their severity, are frequently rooted in immunological processes. A comprehensive grasp of ADR morphology can aid in diagnosis. With the continuous development of new pharmaceuticals, it is noteworthy that certain drugs including immune checkpoint inhibitors have gained notoriety for their association with ADRs. This paper offers an overview of immunological mechanisms involved in cutaneous ADRs with a focus on clinical features and frequently implicated drugs.

Dipeptidyl Peptidase-4 inhibitor associated cutaneous eruptions - A retrospective observational study

BACKGROUND

Dipeptidyl peptidase-4 (DPP-4) plays a complex role in immune regulation and its inhibition can have effects on the pathogenesis of various skin diseases. Studies have shown that DPP-4 inhibitors are associated with an increased risk of bullous pemphigoid.

OBJECTIVES

To analyze the clinical and histopathological features of cutaneous adverse events in patients on DPP-4 inhibitors.

METHODS

We performed a retrospective review of patients with suspected DPP-4 inhibitor associated cutaneous adverse events, at a tertiary teaching hospital from 1^st January 2017 to 31^st December 2020. Patients with previous history of chronic skin disease, those without histopathological reports or follow-up records were excluded. The clinical characteristics, latency period, Naranjo adverse drug reaction probability scale and clinical outcomes were evaluated.

RESULTS

18 patients (M:F-10:8) with a mean age of 68.6 years (range:38-89) were included. The distribution of DPP-4 inhibitors was Teneligliptin (N=6), Vildagliptin (N=6), Sitagliptin (N=4), Linagliptin (N=1) and Saxagliptin (N=1). The mean duration of onset of lesions after the initiation of therapy was 8.8 months (Range:1-24 months). Dermatoses noted were bullous pemphigoid (N=12, 66.6%), lichenoid dermatitis (N=4, 22.2%), psoriasiform dermatitis (N=1, 5.6%) and spongiotic dermatitis (N=1, 5.6%). 8 patients (44.4%) had necrotic keratinocytes as one of the distinct histological features. Causality assessment using the Naranjo adverse event scale place the causative role of DPP-4 inhibitors as 'possible' in all patients. 11 patients (61.1%) noted improvement in their condition following discontinuation of DPP-4 inhibitors, with 5 patients having complete remission within 6 months of stopping the drug.

CONCLUSION

DPP-4 inhibitors associated dermatoses need not necessarily be limited to bullous pemphigoid. It is necessary to recognize the possibility of other dermatoses in patients on DPP-4 inhibitors as substitution of the drug may improve disease morbidity.

SARS-CoV-2 infection as a potential triggering factor for urticarial vasculitis during pregnancy: A case report

During the COVID-19 pandemic, physicians must maintain a high index of suspicion for COVID-19 in cases of urticarial vasculitis or other forms of urticaria. This is particularly important for acute presentations in otherwise asymptomatic individuals and pregnant women, where a prompt approach to the patient can prevent undesirable complications.

Clinicopathological Features of Seborrheic-Like Dermatitis in HIV-Infected Adults: A Single Institutional Descriptive Cross-Sectional Study

BACKGROUND

Atypical and severe clinical presentations of seborrheic-like dermatitis (SLD) are associated with HIV infection, correlating with advanced disease or low CD4 counts. Previous studies documented histological findings characteristic of seborrheic dermatitis in HIV-positive patients.

OBJECTIVE

To expand current knowledge of the clinicopathological characteristics of SLD in South African HIV-seropositive individuals.

METHODS

This prospective study included HIV-seropositive adult patients presenting with SLD to a dermatology clinic from March 2017 to April 2018. A dermatologist established the diagnosis of SLD and the severity of the disease. Detail about antiretroviral therapy (ART), the latest CD4 count, and the viral load was retrieved from the patients' clinical records. Histopathological assessment of the patients' skin biopsies was recorded using standardized data sheets and semiquantifiable grades.

RESULTS

This study included 13 women and 17 men. Fifty percent of patients showed severe or very severe SLD. Six (20.0%) patients presented with erythroderma. Statistical analysis did not show a significant correlation between severity of disease and CD4 count, viral load, or ART, respectively. This study confirmed that the presence of confluent parakeratosis, necrotic keratinocytes, plasma cells, neutrophils with leukocytoclasia, and leukoexocytosis are histopathological clues to SLD occurring in HIV-seropositive patients.

CONCLUSION

SLD in HIV patients may present with varying clinical severity, including erythroderma. The association between the prevalence and severity of SLD with CD4 count, viral load, and ART requires further studies with larger patient populations. The presence of specific histopathological features in a skin biopsy of SLD is a clue to the diagnosis of HIV.

Chlortetracycline and melanin biopolymer - The risk of accumulation and implications for phototoxicity: An in vitro study on normal human melanocytes

Tetracyclines belong to antimicrobial classes with the highest consumption in veterinary medicine and agriculture, which leads to the contamination of the environment and food products, as well as to antibiotic resistance and adverse drug reactions. Chloro-derivatives of tetracyclines are thought to be relatively more phototoxic than others and belong to the most frequently cited drugs as photosensitizers. Melanins are heterogenous biopolymers determining skin, hair and eye colour. They are biosynthesized in a multistep process in melanocytes. Melanins, besides photoprotective and antioxidant properties, may also contribute to adverse skin drug reactions, which involve e.g. hyperpigmentation disorders and phototoxic reactions. Furthermore, they have the ability to form a drug-melanin complex, which leads to deposition of the drug or its metabolites in pigmented tissues. The aim of the study was to examine the ability of chlortetracycline to form a complex with melanin, as well as the effect of the drug on viability, antioxidant defence system and melanogenesis in normal human epidermal melanocytes exposed to the UVA radiation. The obtained results show for the first time that chlortetracycline forms a complex with melanin polymers, which creates a possibility of the drug accumulation in pigmented tissues. A simultaneous exposition of normal melanocytes to chlortetracycline and to the UVA radiation decreases cell viability, proportionally to the drug concentration and the irradiation time. The phototoxic effect appears to be related to the induction of oxidative stress in melanocytes, mainly through an increase of SOD and a decrease of the CAT activity. Chlortetracycline itself does not influence the melanin content or the activity of tyrosinase. The UVA radiation appeared to be a conditioning factor stimulating melanogenesis, whereas the presence of the drug augmented this effect.