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Dermatology > PAPULOSQUAMOUS DISEASES
Parapsoriasis
Article Last Updated: Feb 26, 2007
AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Henry K Wong, MD, PhD, Senior Professional Staff, Department of Dermatology, Henry Ford Hospital
Henry K Wong is a member of the following medical societies: American Academy of Dermatology, American Association of Immunologists, and Society for Investigative Dermatology
Editors: Abby S Van Voorhees, MD, Assistant Professor, Director of Psoriasis Services and Phototherapy Units, Department of Dermatology, University of Pennsylvania School of Medicine, Hospital of the University of Pennsylvania; David F Butler, MD, Professor of Dermatology, Texas A&M University College of Medicine; Director, Division of Dermatology, Scott and White Clinic; Director Dermatology Residency Training Program, Scott and White Clinic; Christen M Mowad, MD, Assistant Professor, Department of Dermatology, Geisinger Medical Center; Joel M Gelfand, MD, MSCE, Medical Director, Clinical Studies Unit, Assistant Professor, Department of Dermatology, Associate Scholar, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania; William D James, MD, Paul R Gross Professor of Dermatology, University of Pennsylvania School of Medicine; Vice-Chair, Program Director, Department of Dermatology, University of Pennsylvania Health System
Author and Editor Disclosure
Synonyms and related keywords:
digitate dermatosis, parapsoriasis en plaque, acuta pityriasis lichenoides, chronica pityriasis lichenoides, small plaque parapsoriasis, large plaque parapsoriasis, mycosis fungoides, MF, cutaneous T-cell lymphoma, CTCL
Background
Parapsoriasis describes a group of cutaneous diseases that can be characterized by scaly patches or slightly elevated plaques that have a resemblance to psoriasis, hence the nomenclature. However, this description includes several inflammatory cutaneous diseases that are unrelated with respect to pathogenesis, histopathology, and response to treatment. Because of the variation in clinical presentation and a lack of a specific diagnostic finding on histopathology, a uniformly accepted definition of parapsoriasis remains lacking.
In 1902, Brocq initially described 3 major entities that fit the description:
- Pityriasis lichenoides (acuta and chronica)
- Small plaque parapsoriasis
- Large plaque parapsoriasis (parapsoriasis en plaque)
Pityriasis lichenoides (acuta and chronica)
Pityriasis lichenoides variants describe scaly dermatoses with necrotic papules that are clinically and histologically different from parapsoriasis. These diseases generally are benign and undergo spontaneous resolution (see Pityriasis Lichenoides for further discussion).
Large plaque and small plaque parapsoriasis
Current terminology of parapsoriasis refers to 2 disease processes that are caused by T-cell–predominant infiltrates in the skin. These disease processes are large plaque parapsoriasis and small plaque parapsoriasis.
As the nomenclature and description of the disease spectrum under the descriptive term parapsoriasis evolved, the primary focus has been on the distinction of whether the disorder progresses to mycosis fungoides (MF) or cutaneous T-cell lymphoma (CTCL). Small plaque parapsoriasis is a benign disorder that rarely if ever progresses. Large plaque parapsoriasis is more ominous in that approximately 10% of patients progress to CTCL. Controversy exists in the classification of large plaque parapsoriasis because some think it is equivalent to the earliest stage CTCL, the patch stage.
The duration of parapsoriasis can be variable. Small plaque disease lasts several months to years and can spontaneously resolve. Large plaque disease is chronic, and treatment is recommended because it may prevent progression to CTCL.
Pathophysiology
The initiating cause of parapsoriasis is unknown, but the diseases likely represent different stages in a continuum of lymphoproliferative disorders from chronic dermatitis to frank malignancy of CTCL.
Small plaque parapsoriasis
Small plaque parapsoriasis likely is a reactive process of predominantly CD4+ T cells. Genotypic pattern observed in small plaque parapsoriasis is similar to that observed in chronic dermatitis, and the pattern of clonality of T cells is consistent with the response of a specific subset of T cells that have been stimulated by an antigen. Multiple dominant clones can be detected by polymerase chain reaction (PCR) of T-cell receptor gene usage, which supports a reactive process. Lymphocytes do not show histologic atypia to suggest malignant transformation. Southern blot analysis of T-cell receptor genes from parapsoriasis does not identify a dominant clone of T cells.
Some physicians believe that small plaque parapsoriasis is an abortive T-cell lymphoma; however, no clear distinguishing evidence, such as genetic changes (eg, TP53 mutations) observed in other malignancies, exists to support this contention. Nevertheless, a hint to the verity of this hypothesis is the recent identification of increased telomerase activity in T cells from CTCL at low-grade stages, high-grade lymphoma, and in parapsoriasis, which is activity not exhibited in normal T cells. A better understanding is likely to develop from further molecular characterization.
Large plaque parapsoriasis
Large plaque parapsoriasis is a chronic inflammatory disorder, and the pathophysiology has been speculated to be long-term antigen stimulation. This disorder is associated with a dominant T-cell clone, one that may represent up to 50% of the T-cell infiltrate. If the histologic appearance is benign, without atypical lymphocytes, classification of large plaque parapsoriasis is made. If atypical lymphocytes are present, many would classify such patients as having patch stage CTCL.
Frequency
United States
No accurate statistics on the incidence and frequency of parapsoriasis exist, but digitate dermatoses may be underreported because of the lack of symptoms and subtle presentation.
Patients may underreport the frequency of large plaque parapsoriasis when it is asymptomatic and subtle. Large plaque parapsoriasis may be greater than the reported incidence of MF, which is approximately 3 cases per million population per year.
International
No reported racial or geographic predilection exists.
Mortality/Morbidity
- Mortality has not been reported for small plaque parapsoriasis. Morbidity is limited to symptoms, which are minimal.
- For large plaque parapsoriasis, mortality may be associated with progression to MF (CTCL). Patch stage of MF represents the early stages of CTCL, and the 5-year survival rate is greater than 90%. Long-term survival is not different from a matched controlled population.
Race
No association with race is noted.
Sex
Small plaque parapsoriasis is associated with male predominance. The male-to-female ratio is 3:1. A slight asymmetry favoring male dominance for large plaque parapsoriasis may exist.
Age
For both small plaque parapsoriasis and large plaque parapsoriasis, presentation most frequently is in middle age; peak incidence is in the fifth decade of life.
History
Onset of parapsoriasis is indolent. It develops from a few patches and becomes more visible over a protracted period of time. Additional lesions develop progressively in some individuals.
- Small plaque parapsoriasis can last months to several years; the disease often resolves spontaneously.
- Large plaque parapsoriasis is a chronic disorder that manifests in an indolent manner and progresses over many years, sometimes decades.
- Large plaque parapsoriasis does not enter remission without treatment.
- The disorder may progress to MF, a CTCL, after an indeterminate number of years.
Physical
- Lesions of small plaque parapsoriasis are well-circumscribed, slightly scaly, light salmon-colored patches that measure less than 5 cm in diameter and are scattered over the trunk and extremities. Digitate pattern is a distinctive form of small plaque disease that consists of palisading elongated fingerlike patches that follow the dermatome and are most prominently displayed on the lateral thorax and abdomen.
- Large plaque parapsoriasis manifests as faint erythematous patches with arcuate geographic borders.
- Each lesion often is greater than 6 cm in diameter.
- Lesions are scattered on the proximal extremities and the trunk.
- Lesions often show a bathing suit distribution.
- Surfaces of the lesions have a faint red-to-salmon color; show flaky thin scales; and have an atrophic, cigarette paper or tissue paper, wrinkling quality.
Causes
No clear etiology for small plaque or large plaque parapsoriasis is known, and no specific association has been made with contact exposure or infections.
Contact Dermatitis, Allergic
Cutaneous T-Cell Lymphoma
Nummular Dermatitis
Pityriasis Alba
Pityriasis Lichenoides
Pityriasis Rosea
Psoriasis, Guttate
Syphilis
Lab Studies
- Complete blood cell count with differential: A high lymphocyte count or the presence of Sézary cells suggests MF/CTCL.
Procedures
- Skin biopsy with immunophenotyping analysis and gene rearrangement studies
Histologic Findings
Histopathology of small plaque parapsoriasis shows a mild superficial perivascular lymphocytic infiltrate with a nonspecific inflammatory infiltrate of CD4+ and CD8+ T cells. However, CD4+ T cells are predominant. The epidermis may show mild spongiosis, focal hyperkeratosis, scale crust, parakeratosis, and occasional exocytosis. Often the pattern is not diagnostic and is nonspecific. Lymphocytes are small and do not show atypical features.
In large plaque parapsoriasis, a superficial dermal inflammatory infiltrate consists predominantly of lymphocytes. Numerous lymphocytes abut the dermal epidermal junction and single lymphocytes can be observed in the epidermis. Lymphocytes are generally small and do not show atypical nuclei. Blood vessels are dilated, and melanophages can be present. The epidermis shows flattening of the rete ridges when epidermal atrophy is prominent on clinical examination. Acanthosis of the epidermis and irregular hyperkeratosis of the cornified layer are present. In contrast to small plaque parapsoriasis, spongiosis is absent.
Gene rearrangement studies can assist in excluding MF or CTCL.
Medical Care
Parapsoriasis can be managed conservatively, based on symptoms. Often, topical treatment is effective.
- Small plaque parapsoriasis usually is asymptomatic. Treatment should be based on alleviation of symptoms associated with scaliness. Patients should be reassured of the benign self-limiting nature of the disease.
- Emollients may be sufficient to treat scaliness; however, a trial of midpotency topical steroids (class 3-5) may lead to greater clinical responsiveness.
- Phototherapy is effective in treating lesions that are widely scattered. Broad- or narrow-band UV-B can be effective and can lead to remission. More recalcitrant presentations can be treated with psoralen and long-wave ultraviolet radiation (PUVA).
- Annual follow-up is recommended. An increase in the number of lesions, an increase in the size of lesions, or the development of induration or epidermal atrophy should prompt a repeat biopsy to consider a diagnosis of MF in evolution.
- Large plaque parapsoriasis should be treated because this may prevent progression to MF (CTCL).
- Therapy includes mid- to high-potency topical steroids (class 2-4), topical nitrogen mustard, and topical carmustine (BCNU).
- Phototherapy with either broad- or narrow-band UV-B or PUVA can be effective in inducing remission.
- Follow-up every 6 months is recommended. Increasing number of lesions, increase in lesion size, or the development of induration or epidermal atrophy should prompt a repeat biopsy to consider a diagnosis of MF in evolution.
Consultations
Consult with a dermatologist specializing in cutaneous lymphoma to coordinate medical care if progression to MF (CTCL) occurs.
Diet
Normal diet without restrictions is indicated.
Activity
Activity is not restricted.
Emollients are helpful in reducing clinically apparent scaliness and mild pruritus. Emollients may be sufficient in small plaque parapsoriasis. Midpotency topical corticosteroids can be useful in small plaque parapsoriasis and large plaque parapsoriasis. UV-B or PUVA (8-methoxypsoralen combined with UV-A phototherapy) can bring about remission of both small and large plaque parapsoriasis.
Drug Category: Corticosteroids
Topical steroids are divided into 7 levels of potency, ranging from ultrapotent fluorinated compounds to low-potency hydrocortisone.
| Drug Name | Triamcinolone (Aristocort) |
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| Description | Anti-inflammatory steroid that suppresses lymphocyte activation and causes vasoconstriction and release of inflammatory mediators. This midpotency formulation fits into class III-V.
Use 0.1% ointment or cream. |
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| Adult Dose | Apply to affected area bid/tid, depending on severity; once response is noted, decrease frequency to maintain efficacy of response |
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| Pediatric Dose | Apply bid to affected area; once response is noted, taper frequency to prevent adverse effects; not to exceed 10 g/wk |
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| Contraindications | Documented hypersensitivity; fungal, viral, and bacterial skin infections |
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| Interactions | None reported |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Do not use in decreased skin circulation; prolonged use, applications over large areas, and use of potent steroids and occlusive dressings may result in systemic absorption; systemic absorption may cause Cushing syndrome, reversible HPA axis suppression, hyperglycemia, and glycosuria |
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Drug Category: Phototherapy agents
After intercalating with DNA and irradiation by UV-A, phototherapy leads to formation of DNA psoralen adducts that cross-link DNA. This affects gene expression by inhibiting DNA replication, mitosis, and cell division.
| Drug Name | Methoxsalen (8-MOP, Oxsoralen) |
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| Description | Photosensitizer that suppresses DNA synthesis by the formation of monoadducts and cross-links between DNA. UV-A (320-400 nm) is required for reaction to occur. PUVA causes selective immunosuppression, selective cytotoxicity, and stimulation of melanocytes. |
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| Adult Dose | 0.3-0.4 mg/kg PO 1.5 h before UV-A exposure; alternatively, 0.57 mg/kg 1.5-2 h before exposure to UV light; treatments are at least 48 h apart |
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| Pediatric Dose | <12 years: Consider topical psoralen
>12 years: Administer as in adults |
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| Contraindications | Documented hypersensitivity; ingestion of photosensitizing drugs; photosensitive disorders (eg, porphyrias, lupus erythematosus, xeroderma pigmentosa), avoid; hepatitic disease; arsenic therapy; breastfeeding |
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| Interactions | Avoid concurrent tolbutamide use; toxicity increases with phenothiazines, griseofulvin, nalidixic acid, tetracyclines, thiazides, and sulfanilamide |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Severe burns may occur from sunlight or UV-A if dose or treatment frequency is exceeded; use only if response to other forms of therapy is inadequate; long-term use may increase risk of skin cancer; must avoid UV-A/sunlight for 24 h and wear protective lenses while outdoors |
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Drug Category: Chemotherapeutic agents
BCNU and nitrogen mustard are both alkylating agents and are not cell-cycle specific. They inhibit DNA, RNA, and protein synthesis.
| Drug Name | Mechlorethamine (Mustargen) |
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| Description | Topical nitrogen mustard that has been used for decades in the treatment of CTCL (MF). Forms interstrand and intrastrand cross-links in DNA, which in turn results in miscoding, breakage, and failure of replication.
Aqueous solution is prepared by combining mechlorethamine 10 mg and 60 mL of water. Normally, application is performed in bathtub to protect against spillage, and the tub is thoroughly rinsed after application. Concentration may be increased to 20 mg or even 40 mg added to the 60 mL of water. Intertriginous areas are painted lightly, and the face and genitalia are spared. Response to treatment may require 3-6 mo.
Ointment formulation is prepared by dissolving 10 mg mechlorethamine in 10 mL of 95% alcohol and mixing with anhydrous ointment base (white petrolatum) in a final concentration of 10 mg/100 g. If total body therapy is required, mix 90 mg in 900 g of white petrolatum. |
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| Adult Dose | Aqueous solution: Apply from neck to toes with small soft paint brush qd
Ointment formulation: Apply from neck to toes qd |
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| Pediatric Dose | Not established |
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| Contraindications | Documented hypersensitivity; preexisting profound myelosuppression or infection; pregnancy or breastfeeding |
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| Interactions | None reported |
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| Pregnancy | D - Unsafe in pregnancy
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| Precautions | Allergic contact sensitivity has occurred in two thirds of patients using aqueous solution but in 5% of patients using ointment; systemic absorption may induce hyperuricemia, suppression of bone marrow, and immunosuppression; monitoring for potential toxicities should be done at least every mo during initiation of therapy; may decrease fertility and is known to be a carcinogen |
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| Drug Name | Carmustine (BiCNU) |
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| Description | Bischloroethylnitrosourea (BCNU) is commonly used in chemotherapy and has proven helpful in treatment of CTCL and related conditions. Alkylates and cross-links DNA strands, inhibiting cell proliferation.
To make aqueous solution, BCNU 100 mg is dissolved in 50 mL of 95% ethanol, yielding a concentration of 2 mg/mL stock solution; 5 mL (10 mg BCNU) of stock solution is diluted in 60 mL of water for total skin coverage; 300 mg of BCNU in 150 mL of ethanol is usually dispensed so that sufficient solution can be mixed up to last a month.
To make the ointment, 10 mL of stock solution (20 mg BCNU) is mixed into 100 g of ointment base (eg, white petrolatum). A 40% ointment concentration may be used but should not be used for >10% of body because of potential for bone marrow suppression. |
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| Adult Dose | Aqueous solution: Apply from neck to toes with small soft paint brush qd
Ointment: Apply from neck to toes qd |
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| Pediatric Dose | Not established |
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| Contraindications | Documented hypersensitivity; myelosuppression from previous chemotherapy |
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| Interactions | Coadministration with cimetidine may increase toxicity; coadministration with etoposide may cause severe hepatic dysfunction (eg, hyperbilirubinemia, ascites, thrombocytopenia) |
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| Pregnancy | D - Unsafe in pregnancy
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| Precautions | Caution in patients with depressed platelet, leukocyte, or erythrocyte counts or hepatic or renal impairment; perform baseline pulmonary function tests; erythema, skin tenderness, and telangiectasias are common adverse effects; BCNU is a weak topical carcinogen |
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Further Outpatient Care
- Patients with small plaque parapsoriasis may have follow-up care every year unless new symptoms or changes in therapy indicate a need for reevaluation. Progression of lesions suggests a need for reevaluation by skin biopsy.
- Large plaque parapsoriasis requires closer follow-up than small plaque parapsoriasis. When treating this disease, follow-up frequency is determined by the treatment modality used. Phototherapy requires an evaluation to response after every 8-12 visits or monthly. Patients using topical treatment need follow-up every 2-3 months. If patients remit or do not desire treatment, follow-up is still recommended to assess for recurrence or progression.
Complications
- Development of contact dermatitis upon administration of topical chemotherapy agents
Prognosis
- Small plaque parapsoriasis may persist in a stable pattern for years to decades and then resolve spontaneously. A small number of cases may progress to MF.
- Large plaque parapsoriasis remains indolent for many years. The disease may progress to CTCL with transformation of lymphocytes from benign small size to larger atypical lymphocytes. The 5-year survival rate, however, still remains high and is greater than 90%.
Medical/Legal Pitfalls
- Parapsoriasis is relatively benign and may persist for many years. Provide follow-up in the case of large plaque parapsoriasis every 6 months because the disease may progress to CTCL.
- Ackerman AB. If small plaque (digitate) parapsoriasis is a cutaneous T-cell lymphoma, even an 'abortive' one, it must be mycosis fungoides!. Arch Dermatol. May 1996;132(5):562-6. [Medline].
- Baskan EB, Tunca B, Cecener G, et al. Analysis of p53 gene mutation in parapsoriasis. J Eur Acad Dermatolo Venereol. 2006;20:882-3. [Medline].
- Burg G, Dummer R, Nestle FO, et al. Cutaneous lymphomas consist of a spectrum of nosologically different entities including mycosis fungoides and small plaque parapsoriasis. Arch Dermatol. May 1996;132(5):567-72. [Medline].
- Herzinger T, Degitz K, Plewig G, Rocken M. Treatment of small plaque parapsoriasis with narrow-band (311 nm) ultraviolet B: a retrospective study. Clin Exp Dermatol. Jul 2005;30(4):379-81. [Medline].
- Hofer A, Cerroni L, Kerl H, Wolf P. Narrowband (311-nm) UV-B therapy for small plaque parapsoriasis and early-stage mycosis fungoides. Arch Dermatol. Nov 1999;135(11):1377-80. [Medline].
- Kikuchi A, Naka W, Harada T, et al. Parapsoriasis en plaques: its potential for progression to malignant lymphoma. J Am Acad Dermatol. Sep 1993;29(3):419-22. [Medline].
- Kim YH, Jensen RA, Watanabe GL, et al. Clinical stage IA (limited patch and plaque) mycosis fungoides. A long-term outcome analysis. Arch Dermatol. Nov 1996;132(11):1309-13. [Medline].
- Koh HK, Charif M, Weinstock MA. Epidemiology and clinical manifestations of cutaneous T-cell lymphoma. Hematol Oncol Clin North Am. Oct 1995;9(5):943-60. [Medline].
- Rook AH, Heald P. The immunopathogenesis of cutaneous T-cell lymphoma. Hematol Oncol Clin North Am. Oct 1995;9(5):997-1010. [Medline].
- Willemze R, Kerl H, Sterry W, et al. EORTC classification for primary cutaneous lymphomas: a proposal from the Cutaneous Lymphoma Study Group of the European Organization for Research and Treatment of Cancer. Blood. Jul 1 1997;90(1):354-71. [Medline].
- Wu K, Lund M, Bang K, Thestrup-Pedersen K. Telomerase activity and telomere length in lymphocytes from patients with cutaneous T-cell lymphoma. Cancer. Sep 15 1999;86(6):1056-63. [Medline].
Parapsoriasis excerpt Article Last Updated: Feb 26, 2007
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