Pityriasis Rubra Pilaris: An Updated Review of Clinical Presentation, Etiopathogenesis, and Treatment Options

Pityriasis rubra pilaris (PRP) is a rare papulosquamous reaction pattern with a significant impact on quality of life. Type I PRP is the most common PRP variant, presenting as erythematous papules emerging in a follicular distribution and later coalescing into plaques with characteristic islands of sparing; histologically, an alternating pattern of orthokeratosis and parakeratosis is considered the hallmark of PRP (checkerboard hyperkeratosis). Other PRP variants (types II-V) differ in their age of onset and clinical presentation. Type VI PRP is a rare PRP subtype associated with human immunodeficiency virus infection and is occasionally associated with diseases of the follicular occlusion tetrad. Caspase recruitment domain family, member 14 (CARD14)-associated papulosquamous eruption and facial discoid dermatitis are newly described disease states that have an important clinical overlap with PRP, creating shared conundrums with respect to diagnosis and treatment. The etiology inciting PRP often remains uncertain; PRP has been suggested to be associated with infection, malignancy, or drug/vaccine administration in some cases, although these are based on case reports and causality has not been established. Type V PRP is often due to inborn CARD14 mutations. Furthermore, recent literature has identified interleukin-23/T-helper-17 cell axis dysregulation to be a major mediator of PRP pathogenesis, paving the way for mechanism-directed therapy. At present, high-dose isotretinoin, ixekizumab, and secukinumab are systemic agents supported by single-arm prospective studies; numerous other agents have also been trialed for PRP, with variable success rates. Here, we discuss updates on clinical manifestations, present new insights into etiopathogenesis, and offer a survey of recently described therapeutic options.

Pityriasis Rubra Pilaris After Moderna COVID-19 Vaccination: A Case Report and Literature Review

ABSTRACT

To date, over 60% of the world's population has received at least 1 dose of coronavirus disease 2019 (COVID-19) vaccination, with over 12 billion doses administered globally. Commonly reported adverse effects of COVID-19 vaccination include fever, headache, myalgia, and injection site reactions. The spectrum of documented cutaneous reactions after COVID-19 vaccination is broad; however, pityriasis rubra pilaris (PRP) or PRP-like eruption secondary to COVID-19 vaccine is exceedingly rare, with only 17 cases previously reported to date in the English literature. In this article, we describe an additional case of COVID-19 vaccination-associated PRP in a 50-year-old woman with a history of metastatic breast carcinoma, who developed a widespread cutaneous eruption characteristic of PRP, including palmoplantar keratoderma, 10 days after her third dose of Moderna COVID-19 vaccine. Punch biopsy specimen showed epidermal hyperplasia with overlying hyperkeratosis, alternating orthokeratosis and parakeratosis and focal follicular plugging, supporting the diagnosis of PRP. The patient improved within weeks of initiating oral acitretin and topical steroids, with resolution achieved after 3 months of continued therapy. To the best of our knowledge, this is the third reported case of Moderna COVID-19 vaccination-associated PRP and collectively the 18 th after the administration of all COVID-19 vaccines currently available, including Pfizer-BioNTech, and AstraZeneca.

Circumscribed Juvenile Pityriasis Rubra Pilaris (Type 4) Koebnerising after a Hot Water Burn: Mild Disease with Maximum Koebner Response

Dear Editor, Pityriasis rubra pilaris (PRP) is a chronic, inflammatory, papulosquamous skin disorder that is characterized by follicular hyperkeratosis and reddish-orange, scaling dermatitis with islands of normal skin (1,2). PRP is classified into 5 groups based on clinical features. Type 4 PRP is characterized by well-demarcated, hyperkeratotic erythematous plaques localized on the elbows and knees with palmoplantar keratoderma (1,2). An 8-year-old girl presented to our clinic with erythematous plaques on both elbows, the legs, and the knees. Plantar keratoderma was noticed on clinical examination. The lesions had started on the elbows and knees about a year ago. The lesions on the leg were surrounded by an irregular, hyperpigmented border. On close inspection, the plaques were formed by follicular papules and mild desquamation was noticed. Upon questioning, it was learned that the lesions on the leg with hyperpigmented borders had emerged after a hot water burn three months ago and that they were localized exactly on the burned areas of the skin (Figure 1). A biopsy was performed on the new lesions, and histopathological evaluation revealed parakeratosis with alternating orthokeratosis, irregular hyperkeratosis, keratotic plugs, and a mild perivascular lymphocytic infiltration around the blood vessels (Figure 2). A diagnosis of PRP was established. The Koebner phenomenon (KP) is described as the development of lesions in previously normal skin after exposure to internal or external trauma such as surgical incisions, burns, friction, insect bites, and allergic and irritant reactions (3). The pathogenesis of KP is not fully understood, but epidermal cell injury and dermal inflammation have been proposed as having a role in the pathophysiology (4). Experimental studies on the mechanism of KP have been performed mostly on patients with psoriasis (3). Disease severity, early age of disease onset, and multiple previous therapies have been found to be associated with KP (5,6). KP has previously been reported after injury with the sharp end of a stick in type 3 PRP, a generalized PRP form (7). However, our patient was diagnosed with type 4 PRP, which is a localized form of the disorder. Griffiths reported type 4 PRP does not evolve to generalized forms (8). In this respect, our case was interesting as maximum Koebner response was observed despite the mild PRP. We therefore believe that disease severity is not a determining factor in KP and that the severity of skin damage plays a crucial role. We also think that changes in the cytokine milieu in the burn area may be responsible for KP, as levels of IL-17 and IL-22, which have been shown to be upregulated in burns, also play a role in PRP pathogenesis (9,10). The disease onset at an early age might have also had a contributing role in the Koebner response in this patient. The hyperpigmented borders of the Koebnerized plaques were also notable as they were spared from KP. Some spared areas were also seen within the Koebnerized plaques themselves. A threshold level of trauma is thought to be necessary for inducing KP (3). The clinical picture of our patient may indicate that the skin damage was much less severe in some areas of the burn, especially in the periphery, and that KP was therefore not observed in these areas. Our case clearly demonstrates that the Koebner response is not related to disease severity. We believe that the type of trauma is an important factor in determining the severity of skin damage and the changes in the cytokine milieu in the involved skin. Early disease onset also seems to contribute to the development of KP. Further studies investigating the mechanism of KP in various skin disorders are necessary. As far as we are aware, this is the first case reporting Koebnerization in the circumscribed juvenile form of PRP.

[Pityriasis rubra pilaris]

Pityriasis rubra pilaris is a rare heterogeneous disorder characterized by follicular keratosis, perifollicular erythema and palmoplantar hyperkeratosis. The aetiology is still unknown. In the majority of cases some triggering factors are found such as trauma or bacterial infection, possibly on a predisposed condition. In other cases, some immunological disorders are associated, and in familial cases a genetic disorder of keratinization has been suggested. The evolution is variable according to the clinical type. The treatment is not well defined, and there is a lack of clinical trials. The best results however are obtained with oral retinoids, methotrexate or ciclosporine as alternative therapy. New TNF inhibitors and anti-IL-12/23 showed a good result and could be have interest in the future.

Paraneoplastic pityriasis rubra pilaris as the presenting manifestation of metastatic squamous cell carcinoma

Pityriasis rubra pilaris (PRP) is a rare idiopathic papulosquamous eruption. Few cases of PRP have been reported in association with malignancies. We report a case of an 83-year-old Caucasian male who presented with recalcitrant paraneoplastic PRP as the presenting manifestation of metastatic squamous cell carcinoma with unknown primary. Treatment with chemotherapy and radiation led to temporary radiologic and symptomatic regression of the cancer as well as resolution of cutaneous findings. This suggests a direct relationship between the PRP and the underlying malignancy in this patient. This case highlights a rare, but important phenomenon in which PRP may act as a harbinger for underlying malignancy.

Letter: Adenocarcinoma of the lung associated with pityriasis rubra pilaris

We describe a case of pityriasis rubra pilaris refractory to conventional treatment, found to be associated with an unrecognized primary adenocarcinoma of the lung. Complete resolution of the eruption followed surgical resection of the tumor.

Pityriasis rubra pilaris: a review of diagnosis and treatment

Pityriasis rubra pilaris (PRP) is a rare inflammatory dermatosis of unknown etiology, and finding a successful therapy can be challenging. PRP occurs equally in men and women. In some patients, associated autoimmune diseases, infections, or malignancies are possible trigger factors. PRP shows a bimodal age distribution, peaking in the first as well as in the fifth to sixth decade. Its classification into five subgroups is based on age at onset, clinical course, morphologic features, and prognosis. More than 50% of patients are best classified as type I with adult-onset PRP. This form is also characterized by high spontaneous remission rates (80%) within 1-3 years. Clinically, the classical adult (type I) and classical juvenile (type III) forms appear to be the same except for the patient's age. Recently, the designation of a new category of PRP (type VI) has been proposed that is characterized by the presence of HIV infection with different clinical features and a poorer prognosis. Typical morphologic features of PRP are erythematosquamous salmon-colored plaques with well demarcated islands of unaffected skin. Often, keratoderma of the palms and soles is present. In patients with extensive disease, ectropion is a dreaded complication. Histology shows hyperkeratosis, alternating orthokeratosis and parakeratosis in a checkerboard pattern, and focal acantholytic dyskeratosis. Descriptions and therapeutic experiences are mainly based on case reports. Mostly, systemic retinoids, methotrexate, and other immunosuppressive agents as well as UV light therapy are applied, with varying response rates. In recent years, treatment with so-called 'biologics' is becoming more and more popular for treating recalcitrant PRP. We present a review of the clinical features, histopathologic findings, classification, differential diagnoses, and treatment of PRP.

Pityriasis rubra pilaris in a HIV-positive patient (Type 6 PRP)

A 45-year-old previously healthy man presented with minimally itchy spiny papular lesions of 3 years' duration and discharging nodular cystic lesions for the past 2 years. Initially, lesions appeared on his ears, followed by the gradual appearance of similar lesions over his face, back, and extremities. The lesions were not associated with photosensitivity. Over the years, the patient continued to have similar lesions without any significant response to various topical medications and oral antibiotics. There was no history of fever or any other systemic complaints and the patient denied any other significant medical problems in the past. Cutaneous examination revealed multiple, grouped, spiny papular lesions coalescing to form plaques at places over the ears, extremities, and trunk (Figure 1). Elongated, horny, follicular spires were noted on the top of the papular lesions. Multiple discharging nodular lesions with crusting were seen predominantly over the chest, abdomen, and back (Figure 2), and closed comedonal lesions were noted on the face and trunk. Multiple orange-brown scaly plaques were seen over the extensor aspect of the patient's thighs (Figure 1, inset). A few nails showed wedge-shaped thickening without subungual hyperkeratosis or other nail changes. Palms, soles, and oral mucosa were normal. Considering the atypical cutaneous findings, the clinical possibility of pityriasis rubra pilaris (human immunodeficiency virus [HIV]-associated type 6 PRP) was considered. Hematoxylin and eosin stain of skin biopsy specimens taken from the spiny papular and plaque lesions revealed marked hyperkeratosis with alternating orthokeratosis and parakeratosis with follicular keratotic plugging (Figure 3; Figure 3, inset). Irregular broad acanthosis was also detected in the epidermis. Dermis showed moderate perivascular lymphomononuclear inflammatory infiltrate. Thus, the skin biopsy was consistent with PRP. HIV serology by enzyme-linked immunosorbent assay (ELISA) with 3 different kits was found to be positive for HIV-1. The patient denied any risk factors associated with acquiring HIV infection, and laboratory values for complete blood cell count, routine serum biochemical profile, and lipid profile were normal. The patient was prescribed oral isotretinoin and asked to come for follow-up for CD4 T-cell count, but did not return.

Pityriasis rubra pilaris: a clinical review

Pityriasis rubra pilaris is a skin condition with many different clinical presentations. History, histology, clinical presentation, its different classified forms, treatments, and differential diagnoses are reviewed.

Paraneoplastic pityriasis rubra pilaris in association with bronchogenic carcinoma

Pityriasis rubra pilaris (PRP) is an uncommon dermatosis occasionally reported in association with an underlying malignancy. We report a 61-year-old woman in whom PRP preceded the diagnosis of bronchogenic carcinoma by approximately 11 months. The clinical picture in this case included atypical cutaneous signs and mucous membrane involvement. Curative treatment of the malignancy with radiotherapy led to resolution of the mucocutaneous changes within months. A presentation of PRP, particularly if atypical, or in an older patient, should prompt consideration of an associated internal malignancy.

Inflammatory myopathy in a patient with cutaneous findings of pityriasis rubra pilaris: a case of Wong?s dermatomyositis

We report the case of a 46-year-old woman presenting cutaneous lesions similar to those of pityriasis rubra pilaris, characterized by diffuse scaling erythroderma and palmoplantar keratoderma; skin biopsy showed follicular hyperkeratosis with a perivascular lymphocytic infiltrate. One year later she developed an inflammatory myopathy; on the basis of clinical features, a diagnosis of dermatomyositis was made. Treatment with prednisone and hydroxychloroquine led to complete control of the cutaneous and muscular involvement, which was maintained during prednisone tapering.

The clinical and histomorphological features of pityriasis rubra pilaris. A comparative analysis with psoriasis

Pityriasis rubra pilaris (PRP) is an idiopathic erythematous scaling eruption which can be difficult to distinguish from psoriasis. We explored the clinical features, including background medical illnesses and potential triggers in patients with PRP, and also its histomorphologic spectrum. Patients with PRP were selected by natural language search of dermatopathology databases containing 250,000 cases accessioned over a 3-year period. A detailed medical history was obtained on each patient via office chart review and patient interviews. We compared the histologic findings in skin biopsies from patients with PRP to those of biopsies matched for site and age from control patients with psoriasis. Certain aspects of the clinical presentations encountered in the study group patients have not been previously emphasized, including eruptions compatible with a vesiculobullous disorder in 4 patients. Several patients had evidence of underlying iatrogenic or systemic immune dysregulatory states and certain triggers could be isolated such as emotional stress and prior exposure to microbial pathogens. Histomorphologic features predictive of PRP included follicular plugging, an increased granular cell layer, and acantholysis. While seen in a minority of biopsies of PRP, morphologic discriminators supportive of a diagnosis of psoriasis included neutrophils in the parakeratotic scale crust, and dermal papillae capillary ectasia with vessels lying in direct apposition to the epidermis. Other morphologic features were encountered in biopsies of PRP which have received little emphasis in the dermatopathology literature, including epithelial atrophy, significant dermal inflammation, the presence of eosinophils and plasma cells within the inflammatory infiltrates, an abnormal granular cell layer, and epidermolytic hyperkeratosis, albeit none were statistically signficant predictors of PRP over psoriasis. Nevertheless, their identification emphasizes the varied histologic spectrum of PRP. The almost ubiquitous finding of acantholysis and the presence of an abnormal granular cell layer in many biopsies of PRP suggests that abnormal keratins or defects in the retinol signalling pathway may be of pathogenetic importance.

Dermatomyositis with a pityriasis rubra pilaris-like eruption: a little-known distinctive cutaneous manifestation of dermatomyositis

A pityriasis rubra pilaris-like eruption has been described in patients with dermatomyositis. These patients showed generalized follicular hyperkeratosis and diffuse thickening of the palms and soles. Histopathological findings consisted of keratotic plugging of the follicular infundibulum and features of erector pili myositis. We report on an 18-year-old woman with dermatomyositis. The diagnosis was established by characteristic enzymatic alterations, electromyographic pattern of myositis and the findings in a muscle biopsy, although the patient had no evidence of muscular weakness during a follow-up of 14 years. She developed an erythematosus and squamous eruption associated with diffuse palmoplantar keratoderma. Histopathological features consisted of a papillomatous epidermis with spicules of compact eosinophilic hyperkeratosis over the tips of papillae that were not related to hair follicles. Pityriasis rubra pilaris-like eruption seems to be a characteristic although uncommon cutaneous manifestation in dermatomyositis.

Pityriasis rubra pilaris as the initial manifestation of internal neoplasia

Pityriasis rubra pilaris (PRP) is a rare papulosquamous disorder of unknown aetiology. There are only three cases reported occurring coincident with internal neoplasia. We report a case of this disorder presenting as the initial manifestation of a previously undiagnosed malignancy with metastases in the liver. The primary tumour was not detected. The patient had a complete remission of his PRP with topical steroids alone, but died of the malignancy.

Photosensitive and phototriggered pityriasis rubra pilaris

We report a 59-year-old man with photosensitive and photodistributed pityriasis rubra pilaris. The phototriggering of the lesions was obtained by the iterative polychromatic phototest (3 times the minimal erythema dose (MED) on 3 consecutive days) and was also observed on the supra MED sites, which began the 10th day and persisted several months. Our results are comparable to those already obtained in photosensitive psoriasis, which helped us to identify the clinical similarities of photosensitivity in these two instances of dermatosis.

Clinical aspect of pityriasis rubra pilaris in childhood

Two patients with pityriasis rubra pilaris (PRP) in childhood were observed. The affection was characterised by an acute onset and relatively short evolution. It was not noted that the disease was familiar. A focal infection of the tonsils which existed prior to the skin lesions in both cases was considered as a provocative factor. PRP of an acute onset in childhood could not be considered as special entity, but as a clinical variety of PRP and is characterised by satisfactory prognosis. Both of our cases were completely cured within 2–3 months. The therapy with penicillin and vitamin A was very effective.