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Extract from the "Textbook of Dermatology"
The PRP Support Group is extremely grateful to Blackwell Scientific for permission to publish the following extract from the "Textbook of Dermatology" 5th Edition, Edited by Champion, and published in 1992. Chapter 30: Disorders of Keratinization: Follicular Keratoses, pages 1358-1362.)
Pityriasis Rubra Pilaris
- Clinical Features
- Laboratory findings
Nomenclature. The term pityriasis rubra pilaris (PRP) has been applied somewhat loosely to a group of patients showing in varying degrees more-or-less circumscribed follicular keratosis, palmoplantar keratoderma and erythroderma. PRP as generally recognized comprises more than one entity  and a working classification has been suggested (Table 30.2).
Table 30.2 Varieties of pityriasis rubra pilaris
|Type I||Adult onset, classical|
|Type II||Adult onset, atypical|
|Type III||Juvenile onset, classical|
|Type IV||Juvenile onset, circumscribed|
|Type V||Juvenile onset, atypical|
Aetiology. The cause of the disease is unknown. The essential abnormality appears to be epidermal over activity [1, 10, 14, 15] as the labelling index is increased from an average normal 3% to 27% and the rate of growth of nails is faster than normal (although not as fast as in psoriasis). The findings may, however, represent epiphenomena to a more basic defect. Finzi and co-workers  reported a decreased level of serum retinal-binding protein in 11 patients and their relatives but this has not been confirmed by others.
Classical PRP affects the sexes equally and occurs at any age from early childhood to the eighth decade. There are, however, two peaks: the highest incidence is between 40 and 60, but there is a second smaller peak in the first decade. It is not certain that the juvenile and adult diseases are identical. Genetic factos have been considered important, but affected relatives are not found in the classical acute-onset varieties (types I and III) and are infrequent in the remainder (types II, IV and V) . The pattern of inheritance when it does occur is usually an autosomal dominant.
Some uncommon cases in children or adults show some features of the classical forms but also many atypical features. Touraine  noted that the juvenile cases with a positive family history showed unusual features.
Finally, there are less infrequent cases in which erythema and follicular keratosis are of very limited extent. The patients are prepubertal children, but a genetic factor has not been established. The term circumscribed juvenile PRP (type IV) has been proposed to describe this group .
Pathology [1,16]. The histological changes in adult classical PRP are distinctive, but vary according to the stage of the process and may therefore differ from site to site in the same patient. A thickened horny layer may consist of plump corneocytes with linear nuclei. The follicles are filled with dense, horny plugs and there are foci of parakeratosis in the perifollicular shoulder and in the epidermis between the follicles (Fig. 30.27). At other sites a basket-weave hyperkeratosis overlies a prominent granular layer and there is little parakeratosis. Thirdly, there may be a normal or thin horny layer shedding corneocytes over an absent or attenuated granular layer.
[Fig. 30.27 Pityriasis rubra pilaris, showing keratotic plug in follicle (x6)]
Although the epidermis is acanthotic it is not, as in psoriasis, thinned above the dermal papillae, and there is no tendency for polymorphonuclear leucocytes to invade the epidermis. Capillaries in the dermis are dilated, but not tortuous, and there is a dermal infiltrate of lymphocytes and histiocytes.
Circumscribed juvenile PRP shows dense lamellated hyperkeratosis with a normal of increased granular layer and little acanthosis. There is little capillary dilation and the sparese cellular infiltrate is mainly histiocytic. The pattern of keratin components on sodium dodecylsulphate-polyacrylamide gel electrophoresis indicates a rapid epidermal turnover, as in normal skin, following adhesive-tape stripping of the stratum corneum, which contrasts markedly with that found in psoriasis . Ultra structural changes of uncertain significance have been reported [1,12].
- Braun Falco O, Ryckmanns F, Schmoeckel C et al.
Pityriasis rubra pilaris: a clinico-pathological and therapeutic study with special reference to histochemistry, autoradiography and electron microscopy.
Arch Derm Res 1983; 275: 287-95.
- Cohen PR, Prystowsky JH.
Pityriasis rubra pilaris: a review of diagnosis and treatment.
J Am Acad Dermatol 1989; 20: 801-7.
- Davidson CL Jr, Winkelmann RK, Keirland RR.
Pityriasis rubra pilaris. A follow-up study of 57 patients.
Arch Dermatol 1969. 100: 175-8.
- Finzi AF, Altomare G, Bergamaschini L et al.
Pityriasis rubra pilaris and retinol-binding protein.
Br J Dermatol 1981; 104: 253-6.
- Gelmetti C, Schiuma AA, Cerri D et al
Pityriasis rubra pilaris in childhood.
Pediatr Dermatol 1986; 6: 446-51.
- Griffiths, WA.
Pityriasis rubra pilaris - an historical approach.
Trans St John's Hosp Dermatol Soc 1975; 61: 58-69.
- Griffiths, WA.
Pityriasis rubra pilaris - an historical approach.
Clin Exp Dermatol 1976; 1: 37-50.
- Griffiths, WA.
Pityriasis rubra pilaris.
Clin Exp Dermatol 1980; 5: 105-12.
- Gross DA, Lindan JW, Newcomer VD.
Pityriasis rubra pilaris: report of a case and analysis of the literature.
Arch Dermatol 1969; 99: 710-16.
- Harper RA, Rispler J.
Pityriasis rubra pilaris epidermal cells in vitro: a comparison with normal and psoriatic cells.
Arch Dermatol Res 1977; 260: 253-5.
- Hunter I, Skerrow D.
The effect of increase tissue turnover on the keratinization of human epidermis.
Biochim Biophys Acta 1981; 674: 155-9.
- Kanerva L, Lauharanta, J, Niemi K-M et al.
Ultra structure of pityriasis rubra pilaris with observations during retinoid (etretinate) treatment.
Br J Dermatol 1983; 108: 653-63.
- Kierland RR, Kulwin M.
Pityriasis rubra pilaris: a clinical study.
Arch Dermatol Syphilol 1950; 61: 925-30.
- Marks R, Griffiths A.
The epidermis in pityriasis rubra pilaris: a comparison with psoriasis.
Br J Dermatol 1973; 89 (Suppl. 9): 19-20 (Abstr.)
- Ralfs IG, Dawber RPR, Ryan TJ et al.
Pityriasis rubra pilaris: epidermal cell kinetics.
Br J Dermatol 1981; 104: 249-52.
- Soeprono FF.
Histologic criteria for the diagnosis of pityriasis rubra pilaris:
Am J Dermatopathol 1986; 6: 277-83.
- Touraine A.
L'heredite dans la pityriasis rubra pilaris.
Ann Dermatol Syphiligr 1942; 2: 175-7.
The disease is rare and affects males and females equally. All races are affected
Classical adult onset PRP (type I). The eruption starts most often on the head, neck, or upper trunk as an erythematous, slightly scaly macule without obvious precipitating factors. Further macules associated with profuse follicular lesions consisting of erythematous perifollicular papules with a central keratotic acuminate plug appear within a few weeks. Follicular lesions appear singly at first and then coalesce to form groups of two, three or more. Irritation is absent initially but may be pronounced as the disease spreads. Interfollicular erythema appears and the follicular lesions are gradually submerged in sheets of erythema with a slightly orange colour (Fig. 30.28) The erythema typically spreads in a cephalocaudal direction . The face becomes uniformly erythematous and mild ecotropion may follow. The scalp shows diffuse bran-like scaling. The palms and soles become hyperkeratotic and yellow (PRP 'sandal') (Fig. 30.28). Erythroderma frequently develops within 2-3 months. In most cases sharply demarcated islands of unaffected skin 1 cm in diameter remain as a helpful diagnostic sign . Islands of deeper erythema are sometimes seen. The nails are grossly thickened and discoloured distally showing splinter haemorrhages, but there is no dystrophy of the nail plate and pitting is minimal, features which separate it from psoriasis  (Fig. 30.29). Spontaneous resolution occurs in 80% of patients in 1-3 years. In the resolving stage the eruption resembles seborrhoeic dermatitis. Relapses are recognized but are uncommon [2, 6]. Myasthenia [1>, 14] and hypothyroidism  are rare associations, and occasional patients have developed leukaemia  or multiple seborrhoeic warts .
[Fig 30.28 Pityriasis rubra pilaris; keratoderma of the palm.]
[Fig 30.29 Pityriasis rubra pilaris; thickening of the nails, subungual hyperkeratosis and splinter haemorrhages.]
Atypical adult onset (type II). This uncommon variety affects some 5% of patients. The disease shows atypical morphological features and starts in adult life. Follicular hyperkeratosis in prominent in some areas while more lamellar scaling may be seen elsewhere, especially on the legs. Many patients show areas of eczematous change. The orderly caudal progression seen in type I does not occur and there is less tendency for the disease to become erythrodermic.
Classical juvenile PRP (type III). (Figs 30.30 & 30.31). The onset is between the ages of 5 and 10 and shows all the features of type I PRP, of which it may be the juvenile counterpart. In 3 of 4 patients, the PRP rapidly followed an acute infection . Spontaneous clearing is common within 1-2 years [4, 8]. The atypical varieties described below are less exanthematic and have a poorer prognosis.
[Fig 30.30 Pityriasis rubra pilaris - Type III. Cephalocaudal spread with confluent erthyema in upper half and follicular papules still visible from mid-trunk downwards.]
[Fig 30.31 Pityriasis rubra pilaris - Type III; islands of sparing and follicular papules running to the confluence at extending margin.]
Circumscribed juvenile PRP (type IV). Several years after birth, well-demarcated plaques of follicular plugging with variable degrees of erythema appear on the knees and elbows (Fig. 30.32). A few scattered scaly erythematous macules are often found on the trunk or in the scalp. Some case also show marled palmoplantar keratoderma. The histological changes in this type are more reminiscent of psoriasis but lack the formation of neutrophil microabcess. Despite the resemblance to localized psoriasis, no case have been observed to progress to psoriasis vulgaris. Keratosis circumscripta (q.v.) seen in Africa is very similar and perhaps identical. The prognosis is uncertain but in some cases clear in the late teens.
[Fig 30.32 Circumscribed juvenile PRP showing well-demarcated plaques of follicular plugging.]
Atypical juvenile PRP (type V). Patients in this group show erythema and hyperkeratosis at birth or in the first few years of life. Keratoderma is common and the presence of follicular plugging and erythema suggest a diagnosis of PRP. However it is probable that the group overlaps with several poorly defined icthyotic disorders including follicular icthyiosis  and the erythrokeratodermas. Several patients have shown a scleroderma-like change of the digits. There is little tendency for the disorder to clear spontaneously.
- Aguilar AR, Gomez F, Balsa FT et al
Pityriasis rubra pilaris with muscle and joint involvement
Dermatologica 1973; 146: 361-6.
- Dugois P, Colomb L, Ambland P.
Pityriasis rubra-pilaire. Seconde pousee chez un enfant de sans.
Bull Soc Fr Dermatol Syphiligr 1963; 70: 924-5.
- Tunnessen WW Jr, Neburg PI, Voorhess ML.
Hypothyroidism and pityriasis rubra pilaris. Response to thyroid hormone.
J Pediatr 1976; 88: 456-8.
- Gelmetti C, Schuima AA, Cerri D et al.
Pityriasis rubra pilaris in childhood - a long term study of 29 years.
Pediatr Dermatol 1986; 3: 446-51.
- Griffiths, WAD.
Juvenile pityriasis rubra pilaris (type III). In: Wilkinson DS, Mascaro JM, Orfanos CE, eds.
Clinical Dermatology Berlin CMD Case Collection. Stuttgart: Schattauer, 1987: 131-2.
- Griffiths WAD, Hall-Smith P.
Pityriasis rubra pilaris with relapses.
Br J Dermatol 1981; 105 (Suppl. 19): 59.
- Griffiths WAD, Pieris S.
Pityriasis rubra pilaris - an autoradiographic study.
Br J Dermatol 1982; 107: 665-7.
- Griffiths WAD.
Pityriasis rubra pilaris.
J Am Acad Dermatol 1984; 10: 1086-8.
- Hazell M, Marks R.
Br J Dermatol 1984; 111: 101-9.
- Larregue M, Champion R, Bressieux J-M et al.
Le pityriasis rubra pilaire aigu de l'enfant.
Ann Dermatol Venereol 1983; 110: 221-8.
- Reinhardt LA, Rosen T.
Pityriasis rubra pilaris as the initial manifestation of leukemia.
Cutis 1983; 31: 100-2.
- Schwengle LEM, Rampen FHJ.
Eruptive seborrheic keratoses associated with erythrodermic pityriasis rubra pilaris.
Acta Derm Venereol 1989; 68: 443-5.
- Sonnex TS, Dawber RPR, Zachary CB et al.
The nails in adult type I pityriasis rubra pilaris - a comparison with Sezary syndrome and psoriasis.
J Am Acad Dermatol 1986; 15: 956-60.
- Waldorf DS, Humbrick GW, Jr.
Vitamin A-responsive pityriasis rubra pilaris with myasthenia gravis.
Arch Dermatol 1965; 92: 424-7.
Laboratory findings Haematological and biochemical findings are normal. Plasma vitamin A and carotenoids are normal [6, 11], but a low retinol-binding protein has been reported and disputed . Saurat's group found elevated CRBP and CRABP levels similar to plaques of psoriasis . Studies of HLA typing and direct immunofluorescence were negative . Takematsu has reported a normal level of LTB4 and low levels of anaphylatoxins in scale extract from PRP, within the range found for normal non-inflamed skin and differing from psoriatic scale [16,17]. Shvili reported activated T-suppresor cells and impairment of T-helper cells . Lectin marking of keratinocytes for b-D-galactose was increased . A different keratin marker (PKK2) showed predominantly basal marking, whereas psoriatic plaques showed marking throughout the epidermis .
Diagnosis Acceptance of the clinical and histological heterogeneity of PRP imposes rigid diagnostic criteria. PRP in adults or children may be difficult to diagnose with complete confidence in its early or later stages, when some of the distinctive signs may be lacking. Repeated observation and a number of biopsies may be necessary. Psoriasis, notably follicular psoriasis in children, may present difficulties, but these are resolved by the course or the histological demonstration of psoriasis. Some differences between psoriasis and PRP are indicated in Table 30.3.
'Atypical PRP' must be regarded as a provisional diagnostic category. Such cases may ultimately acquire other labels.
Circumscribed juvenile PRP must be differentiated from the erythrokeratodermas such as Gottron's syndrome (p. 1350).
Table 30.3 Differences between pityriasis rubra pilaris and psoriasis
|Age at onset||Bimodal||Second decade|
|'Islands' of pale skin||Constant||Less common|
|Nail changes||No salmon patches||Present|
|Nail growth rate||Moderate increase||Marked increase|
|Epidermal kinetics||Moderate increase||Marked increase|
|Munro microabcesses||Very rare||Common|
|Response to methotrexate||Poor||Good|
|PAGE electrophoresis||'Stripping' pattern||Reduced 70K|
Treatment. The assessment of the value of treatment is difficult because the natural course of the conditions reported as PRP is so variable. With present diagnostic criteria classical PRP of adults has been shown to have a relatively good prognosis and it is questionable whether those who have claimed benefit from cycotoxic drugs or corticosteroids have always taken the natural history into account. Rest and bland applications should be advised. If the erythrodermic phase is active, etretinate can be used at a dosage of 0.75mg/kg . However, results are unpredictable with some patients showing dramatic clearing while others appear to be resistant to systemic retinoids. Isotretinoin has also been used successfully [3, 5]. Topical and systemic steroids are ineffective. Toxic doses of oral vitamin A (up to 1 mega-unit daily for 2 weeks) produce a brisk exfoliation followed by resolution in a few patients, but relapses are common and toxicity limits the value of this therapy .
Cytostatic agents such as methotrexate are disappointing but can be tried if retinoids fail [1, 8]. At the time of writing two personal cases have failed to respond to cyclosporin therapy, as did a case of Meyer .
Oxholm reported a case receiving cytostatics, retinoids, PUVA and cyclosporin who developed a squamous cell carcinoma of the parotid . PUVA usually exacerbates the condition but occasional successes have been reported .
A bibliography of over 1000 references on PRP was published in 1983 .
- Anderson FE.
Pityriasis rubra pilaris treated with methotrexate.
Aust J Dermatol 1965; 8: 183-5.
- Brenner W, Gschnait F, Honigsmann H et al.
The testing of photochemotherapy in various dermatoses.
Hautarzt 1978; 29: 541-4.
- Dicken CH.
Isotretinoin treatment of pityriasis rubra pilaris.
J Am Acad Dermatol 1987; 16: 297-301.
- Fleissner J, Happle R.
Etretinate in the treatment of juvenile pityriasis rubra pilaris.
Arch Dermatol 1981; 117: 749-50.
- Goldsmith LA, Weinrich AE, Shupack J.
Pityriasis rubra pilaris response to 13-cis-retinoic acid (isoretinoin).
J Am Acad Dermatol 1982; 6 (Suppl.): 710-5.
- Griffiths WA.
Vitamin A and pityriasis rubra pilaris.
J Am Acad Dermatol 1982; 7: 555 (letter).
- Kariniemi AL, Virtanen I.
Altered keratin expression in benign and malignant skin disease revealed with monoclonal antibodies.
Am J Dermatopathol 1989; 11: 202-8.
- Knowles WR, Chernowsky ME.
Pityriasis rubra pilaris. Prolonged treatment with methotrexate.
Arch Dermatol 1970; 102: 603-12.
- Kuster W.
Pityriasis rubra pilaris.
Bibliogr Genet Med 1983; 17: 1-86.
- Meyer P, van Voorst PC.
Lack of effect of cyclosporin A in pityriasis rubra pilaris.
Acta Derm Venereol 1989; 69: 272.
- Niemi KM, Kousa M, Storgards K et al.
Pityriasis rubra pilaris. A clinico-pathalogical study with a special reference to autoradiography and histocompatability antigens.
Dermatologica 1976; 152: 109-18.
- Ojeda LM, Bosca AR, Cavero FV.
Marcaje mediante lectinas de trastornos en la queratinizacion II.
Med Cut Ib Lat Amer 1988; 16: 183-6.
- Oxholm A, Homsen K, Menne T.
Squamous cell carcinoms in relation to cyclosporin therapy of non-malignant skin disorders.
Acta Derm Venereol 1988; 69: 89-90.
- Randle DW, Diaz-Perez JL, Winkelmann RK.
Toxic doses of vitamin A for Pityriasis rubra pilaris.
Arch Dermatol 1980; 116: 888-92.
- Shvili D, David M, Mimouni M.
Childhood-onset pityriasis rubra pilaris with immunologic abnormalities.
Pediatr Dermatol 1987; 4: 21-3.
- Seigenthaler G, Saurat JH, Salomon D et al.
Skin cellular retinoid-binding proteins and retinoid-responsive dermatoses.
Dermatologica 1986; 173: 163-73.
- Takematsu H, Ohkohchi K, Tagami H.
Demonstration of anaphylatoxins C3a C4a and C5a in the scales of psoriasis and inflammatory pustular dermatoses.
Br J Dermatol 1986; 114: 1-6.
- Takematsu H, Terui T, Tagami H.
Demonstration of leukotriene B4 in the scales of psoriasis and inflammatory pustular dermatoses.
Acta Derm Venereol 1986; 66: 6-10.
- Valquist A.
Retinol binding protein and pityriasis rubra pilaris.
Br J Dermatol 1982; 107: 125-7 (letter).