HIV-associated pruritus: etiology and management

HIV: Inflammatory dermatoses

Patients living with HIV may experience a variety of inflammatory dermatoses, ranging from exacerbations of underlying conditions to those triggered by HIV infection itself. This article presents a current literature review on the etiology, diagnosis and management of atopic dermatitis, psoriasis, pityriasis rubra pilaris, lichen planus, seborrheic dermatitis, eosinophilic folliculitis, pruritic papular eruption and pruritus, in patients living with HIV.

HIV-Associated Immune Dysregulation in the Skin: A Crucible for Exaggerated Inflammation and Hypersensitivity

Skin diseases are hallmarks of progressive HIV-related immunosuppression, with severe noninfectious inflammatory and hypersensitivity conditions as common as opportunistic infections. Conditions such as papular pruritic eruption are AIDS defining, whereas delayed immune-mediated adverse reactions, mostly cutaneous, occur up to 100-fold more during HIV infection. The skin, constantly in contact with the external environment, has a complex immunity. A dense, tightly junctioned barrier with basal keratinocytes and epidermal Langerhans cells with antimicrobial, innate-activating, and antigen-presenting functions form the frontline. Resident dermal dendritic, mast, macrophage, and innate lymphoid cells play pivotal roles in directing and polarizing appropriate adaptive immune responses and directing effector immune cell trafficking. Sustained viral replication leads to progressive declines in CD4 T cells, whereas Langerhans and dermal dendritic cells serve as viral reservoirs and points of first viral contact in the mucosa. Cutaneous cytokine responses and diminished lymphoid populations create a crucible for exaggerated inflammation and hypersensitivity. However, beyond histopathological description, these manifestations are poorly characterized. This review details normal skin immunology, changes associated with progressive HIV-related immunosuppression, and the characteristic conditions of immune dysregulation increased with HIV. We highlight the main research gaps and several novel tissue-directed strategies to define mechanisms that will provide targeted approaches to prevention or treatment.

Common and discrete mechanisms underlying chronic pain and itch: peripheral and central sensitization

Normally, an obvious antagonism exists between pain and itch. In normal conditions, painful stimuli suppress itch sensation, whereas pain killers often generate itch. Although pain and itch are mediated by separate pathways under normal conditions, most chemicals are not highly specific to one sensation in chronic pathologic conditions. Notably, in patients with neuropathic pain, histamine primarily induces pain rather than itch, while in patients with atopic dermatitis, bradykinin triggers itch rather than pain. Accordingly, repetitive scratching even enhances itch sensation in chronic itch conditions. Physicians often prescribe pain relievers to patients with chronic itch, suggesting common mechanisms underlying chronic pain and itch, especially peripheral and central sensitization. Rather than separating itch and pain, studies should investigate chronic itch and pain including neuropathic and inflammatory conditions. Here, we reviewed chronic sensitization leading to chronic pain and itch at both peripheral and central levels. Studies investigating the connection between pain and itch facilitate the development of new therapeutics against both chronic dysesthesias based on the underlying pathophysiology.

Phototherapy in Skin of Color

Phototherapy in skin of color requires special consideration. Pigmented skin is an efficient ultraviolet filter. Hence, higher doses of ultraviolet radiation are generally more effective and well tolerated in skin of color. An objective and practical system has not yet been established to determine optimal phototherapy dosing in skin of color. The authors recommend obtaining a detailed history of each individual patient's response to sun exposure before prescribing a phototherapy dosing regimen. In addition, providers should consider the role of socioeconomic factors and their impact on phototherapy-related outcomes, including barriers to access and compliance.

Infectious differential diagnosis of chronic generalized pruritus without primary cutaneous lesions: a review of the literature

Pruritus is one of the most common complaints among patients referred to a dermatology clinic. "Chronic generalized pruritus" is described as the sensation of itching on the entire body surface, which lasts at least 6 or more weeks. This symptom can be a disabling phenomenon for patients and may sometimes interfere with daily activities such as sleep. If specific dermatological findings are observed, the physician easily comes to a diagnosis and treats the condition, whereas, when primary lesions are not detected, the diagnosis can become challenging, and some patients have to undergo extensive evaluations. The association between some systemic disorders and chronic generalized pruritus is widely known and confirmed. Many infections have been associated with pruritus, but few are considered to cause chronic generalized pruritus without any characteristic skin lesions. We aimed to gather all the available data on infectious causes of chronic generalized pruritus with no diagnostic cutaneous lesions to assist fellow physicians in the process of evaluation of these challenging cases.

Treatment-resistant prurigo nodularis: challenges and solutions

Prurigo nodualris (PN) is a chronic condition with highly pruritic, hyperkeratotic papules or nodules arising in the setting of chronic pruritus. While PN may serve as a phenotypic presentation of several underlying conditions such as atopic dermatitis, chronic kidney disease-related pruritus, and neurological diseases, it represents a distinct clinical entity that may persist despite the removal of the underlying cause, if one is identified. Neuronal proliferation, eosinophils, mast cells, and small-fiber neuropathy play a role in the production of pruritus in PN, although the exact mechanism has not yet been established. Identifying an underlying cause, if present, is essential to prevent recurrence of PN. Due to often present comorbidities, treatment is typically multimodal with utilization of topical and systemic therapies. We performed a PubMed/MEDLINE search for PN and present a review of recent developments in the treatment of PN. Treatment typically relies on the use of topical or intralesional steroids, though more severe or recalcitrant cases often necessitate the use of phototherapy or systemic immunosuppressives. Thalidomide and lenalidomide can both be used in severe cases; however, their toxicity profile makes them less favorable. Opioid receptor antagonists and neurokinin-1 receptor antagonists represent two novel families of therapeutic agents which may effectively treat PN with a lower toxicity profile than thalidomide or lenalidomide.

Immune reconstitution inflammatory syndrome associated with dermatophytoses in two HIV-1 positive patients in rural Tanzania: a case report

Background

Immune reconstitution inflammatory syndrome associated with dermatophytoses (tinea-IRIS) may cause considerable morbidity. Yet, it has been scarcely reported and is rarely considered in the differential diagnosis of HIV associated cutaneous lesions in Africa. If identified, it responds well to antifungals combined with steroids. We present two cases of suspected tinea-immune reconstitution inflammatory syndrome from a large HIV clinic in rural Tanzania.

Cases presentation

A first case was a 33 years-old female newly diagnosed HIV patient with CD4 count of 4 cells/μL (0 %), normal complete blood count, liver and renal function tests was started on co-formulated tenofovir/emtricitabine/efavirenz and prophylactic cotrimoxazole. Two weeks later she presented with exaggerated inflammatory hyperpigmented skin plaques with central desquamation, active borders and scratch lesions on the face, trunk and lower limbs. Tinea-IRIS was suspected and fluconazole (150 mg daily) and prednisolone (1 mg/Kg/day tapered down after 1 week) were given. Her symptoms subsided completely after 8 weeks of treatment, and her next CD4 counts had increased to 134 cells/μL (11 %). The second case was a 35 years-old female newly diagnosed with HIV. She had 1 CD4 cell/μL (0 %), haemoglobin 9.8 g/dl, and normal renal and liver function tests. Esophageal candidiasis and normocytic-normochromic anaemia were diagnosed. She received fluconazole, prophylactic cotrimoxazole and tenofovir/emtricitabine/efavirenz. Seven weeks later she presented with inflammatory skin plaques with elevated margins and central hyperpigmentation on the trunk, face and limbs in the frame of a good general recovery and increased CD4 counts (188 cells/μL, 6 %). Tinea-IRIS was suspected and treated with griseofulvin 500 mg daily and prednisolone 1 mg/Kg tapered down after 1 week, with total resolution of symptoms in 2 weeks.

Conclusion

The two cases had advanced immunosuppression and developed de-novo exaggerated manifestation of inflammatory lesions compatible with tinea corporis and tinea facies in temporal association with antiretroviral treatment initiation and good immunological response. This is compatible with unmasking tinea-IRIS, and reminds African clinicians about the importance of considering this entity in the differential diagnosis of patients with skin lesions developing after antiretroviral treatment initiation.

Frequency, pattern, and extent of skin diseases in relation to CD4+ cell count among adults with human immunodeficiency virus infection or acquired immunodeficiency syndrome in Osogbo, southwestern Nigeria

BACKGROUND

Skin diseases characterize all stages of human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) and contribute significantly to associated morbidity and mortality.

OBJECTIVES

The aim of this study was to document the prevalences, patterns, and extents (severity) of skin diseases and their relationships with immunologic status in HIV/AIDS patients.

METHODS

A total of 140 HIV/AIDS patients in different stages of HIV infection and 140 controls were recruited. Skin diseases were documented and CD4+ cell counts determined in all subjects. Severity was assessed according to the body surface area affected (using the Wallace rule of nines and the rule of palm) for lesions that tended to be widespread. The number of digits involved was counted for lesions involving the nails. Intensity of pain was graded for specific conditions such as herpes zoster. Chi-squared statistics and Pearson correlations were determined.

RESULTS

Mean±standard deviation age was 35.04±8.83 years in the patient group and 32.21±8.30 years in the control group. The prevalences and patterns of skin diseases in HIV/AIDS patients were similar to those reported in previous studies. Most commonly found dermatoses were oral candidiasis (n=28, 20.0%), pruritic papular eruption (n=27, 19.3%), xeroderma (n=23, 16.4%), dermatophytosis (n=22, 15.7%), and fluffy hair (n=19, 13.6%). The presence of specific skin lesions represented a better correlate with immunosuppression than cutaneous extents. However, the extents of viral warts and multiple blue–black nails correlated significantly with CD4+ cell count. The presence of a lighter hair color phenotype signifies a lower CD4+ cell count than a softer hair phenotype.

CONCLUSIONS

The presence of specific skin lesions correlates more strongly with a low CD4+ cell count than does the extent of their distribution, except in cases of viral warts. The presence of and higher numbers of nails affected with blue–black nail hyperpigmentation suggest severe immunosuppression.

The neurology of itch

Research over the past 15 years has helped to clarify the anatomy and physiology of itch, the clinical features of neuropathic itch syndromes and the scientific underpinning of effective treatments. Two itch-sensitive pathways exist: a histamine-stimulated pathway that uses mechanically insensitive C-fibres, and a cowhage-stimulated pathway primarily involving polymodal C-fibres. Interactions with pain continue to be central to explaining various aspects of itch. Certain spinal interneurons (Bhlhb5) inhibit itch pathways within the dorsal horn; they may represent mediators between noxious and pruritic pathways, and allow scratch to inhibit itch. In the brain, functional imaging studies reveal diffuse activation maps for itch that overlap, but not identically, with pain maps. Neuropathic itch syndromes are chronic itch states due to dysfunction of peripheral or central nervous system structures. The most recognized are postherpetic itch, brachioradial pruritus, trigeminal trophic syndrome, and ischaemic stroke-related itch. These disorders affect a patient's quality of life to a similar extent as neuropathic pain. Treatment of neuropathic itch focuses on behavioural interventions (e.g., skin protection) followed by stepwise trials of topical agents (e.g., capsaicin), antiepileptic drugs (e.g., gabapentin), injection of other agents (e.g., botulinum A toxin), and neurostimulation techniques (e.g., cutaneous field stimulation). The involved mechanisms of action include desensitization of nerve fibres (in the case of capsaicin) and postsynaptic blockade of calcium channels (for gabapentin). In the future, particular histamine receptors, protease pathway molecules, and vanilloids may serve as targets for novel antipruritic agents.

Pruritus in HIV-infected patients in the era of combination antiretroviral therapy: a study of its prevalence and causes

Pruritus is a common symptom in HIV-infected patients. However, there is a lack of studies examining this symptom. We investigated the prevalence of pruritus and its causes in this population by offering the possibility of participating in a skin health programme to all HIV-infected patients who attended our service in Alicante, Spain. Those who accepted (n = 303) underwent an interview and a detailed physical examination by specialists from the Dermatology Department. Between May 2003 and October 2003, 94 patients (31%) reported pruritus: xerosis, seborrhoeic eczema and interdigital tinea pedis were the most frequent dermatological entities responsible for this symptom. Patients with pruritus had higher viral loads (P = 0.006). We conclude that pruritus is still a frequent symptom in HIV-infected patients. To the best of our knowledge this is the first prevalence study of pruritus in an HIV population in the combination antiretroviral therapy (cART) era.

New insights into HIV-1-primary skin disorders

Since the first reports of AIDS, skin involvement has become a burdensome stigma for seropositive patients and a challenging task for dermatologist and infectious disease specialists due to the severe and recalcitrant nature of the conditions. Dermatologic manifestations in AIDS patients act as markers of disease progression, a fact that enhances the importance of understanding their pathogenesis.

Broadly, cutaneous disorders associated with HIV type-1 infection can be classified as primary and secondary. While the pathogenesis of secondary complications, such as opportunistic infections and skin tumours, is directly correlated with a decline in the CD4⁺ T cell count, the origin of the certain manifestations primarily associated with the retroviral infection itself still remains under investigation.

The focus of this review is to highlight the immunological phenomena that occur in the skin of HIV-1-seropositive patients, which ultimately lead to skin disorders, such as seborrhoeic dermatitis, atopic dermatitis, psoriasis and eosinophilic folliculitis. Furthermore, we compile the latest data on how shifts in the cytokines milieu, impairments of the innate immune compartment, reactions to xenobiotics and autoimmunity are causative agents in HIV-1-driven skin diseases. Additionally, we provide a thorough analysis of the small animal models currently used to study HIV-1-associated skin complications, centering on transgenic rodent models, which unfortunately, have not been able to fully unveil the role of HIV-1 genes in the pathogenesis of their primarily associated dermatological manifestations.

Chronic pruritus in the absence of specific skin disease: an update on pathophysiology, diagnosis, and therapy

Chronic pruritus is a major and distressing symptom of many cutaneous and systemic diseases and can significantly impair the patient's quality of life. Pruritus perception is the final result of a complex network involving dedicated nerve pathways and brain areas, and an increasing number of peripheral and central mediators are thought to be involved. Itch is associated with most cutaneous disorders and, in these circumstances, its management overlaps with that of the skin disease. Itch can also occur without associated skin diseases or primary skin lesions, but only with nonspecific lesions secondary to rubbing or scratching. Chronic itch with no or minimal skin changes can be secondary to important diseases, such as neurologic disorders, chronic renal failure, cholestasis, systemic infections, malignancies, and endocrine disorders, and may also result from exposure to some drugs. The search for the cause of pruritus usually requires a meticulous step-by-step assessment involving careful history taking as well as clinical examination and laboratory investigations. Few evidence-based treatments for pruritus are available. Topical therapy, oral histamine H(1) receptor antagonists, and phototherapy with UV radiation can target pruritus elicitation in the skin, whereas antiepileptic drugs, opioid receptor antagonists, and antidepressants can block signal processing in the CNS.

[Frequent and rare dermatological diseases in HIV patients]

HIV patients develop a variety of infectious and non-infectious diseases of the skin and mucous membranes. Some of these serve as indicator diseases for a weakening immune system. While none of the dermatological complications is pathognomonic, conditions such as oral hairy leukoplakia, herpes zoster, thrush, and eosinophilic folliculitis should make physicians consider the possibility of underlying HIV disease. Moreover, one has to consider HIV if these skin diseases take an atypical or severe course, or if they do not respond properly to appropriate medication. Frequent and rare dermatoses occurring in HIV infection are discussed.

Inflammatory Noninfectious Dermatoses of HIV

Since the advent of HIV/AIDS, a variety of inflammatory noninfectious skin conditions have been described in HIV-infected patients. This review will discuss a group of inflammatory, noninfectious dermatoses that, although not exclusive to HIV/AIDS, are commonly observed in HIV-infected patients and pose an apparent paradox in a disease that supposedly involves suppression of cellular immunity.