doi: 10.1111/j.1346-8138.2011.01367.x Journal of Dermatology 2011; 38: 1–2

LETTER TO THE EDITOR

Retrospective study of 24 patients with large or small plaqueparapsoriasis treated with ultraviolet B therapy

Table 1. Clinical characteristics

SPP (%) LPP (%)

Number of patients 8 16

Disease history, years

Median 0.4 2

Range 0.1–30 0.1–20Sex

Male 2 (25) 10 (62.5)

Age, yearsMedian 54 52.5

Range 32–69 26–76

Atypical cells 1 (12.5) 13 (81.25)

LPP, large plaque parapsoriasis; SPP, small plaque parapsoriasis.

Table 2. Clinical characteristics and outcome

All

patients (%)

Healed

(%)

Active

(%)

Developed

MF (%)

Number of patients 24 5 18 1

Sex

Male 12 (50) 3 (60) 8 (44) 1 (100)Age, years

Median 54 55 52

Range 26–76 32–69 26–76 74Disease

LPP 16 (67) 2 (40) 13 (72) 1 (100)

Atypical cells 14 (58) 2 (40) 11 (61) 1 (100)

No. of exposuresMedian 55 51 60

Range 16–196 18–101 23–196 –

Phototherapy

duration, yearsMedian 2 3.5 2

Range 0.3–5.5 0.5–4.8 1.1–5.5 –

LPP, large plaque parapsoriasis; MF, mycosis fungoides.

Dear Editor,

More than a 100 years ago, parapsoriasis en plaque was character-

ized by Brocq as a chronic inflammation of the skin with an

unknown etiology which is resistant to treatment. The possibility of

malignant change in this condition has been documented,1–3 but

the effect of phototherapy in preventing malignant change has not

been fully investigated.

A retrospective study was performed to evaluate the clinical out-

comes of patients with parapsoriasis en plaques who consulted the

Osaka Red Cross Hospital between April 1996 and December

2005. The study protocol was approved by the hospital review

board. Osaka Red Cross Hospital is a referral medical center and

patients with an advanced stage of disease were included in this

series. If the maximum size of the lesion was 6 cm or less, the

lesions were categorized as small plaque parapsoriasis (SPP). If the

size of the lesion was more than 6 cm, the lesions were categorized

as large plaque parapsoriasis (LPP).2 None of the patients had axil-

lary or inguinal lymphadenopathy. The laboratory results of all

patients were unremarkable.

The mean light intensity of the broadband ultraviolet (UV)-B was

0.46 mW ⁄ cm2 and narrowband UV-B was 5.0 mW ⁄ cm2 as mea-

sured by the integrated light-detecting instrument (X96 Irradiance

Meter; Gigahertz-Optik, Newburyport, MA, USA). UV-B therapy was

conducted once a week. If all of the lesions disappeared, UV-B ther-

apy was conducted once or twice a month thereafter or discontin-

ued. The first exposure was 50% of the predetermined minimal

erythema dose on the trunk. Successive doses were determined

using the following guidelines: if the previous exposure had not

caused any perceptible effect, the next exposure time was

increased by 20%; if the previous exposure had induced a slight

erythema, the same exposure time was repeated; and if there was

marked erythema, the next exposure time was decreased by 20%.

In addition to phototherapy, the patients received topical emollients

and corticosteroids for their symptoms. There was no evidence of

skin cancer as a side-effect of the phototherapy.

Tables 1 and 2 summarize the results of both Japanese and

Korean patients. Only one patient with LPP progressed to myco-

sis fungoides (MF) and died as a result. This patient was male

and did not have a long history of LPP, but the eruption

involved a large area of the body including the head, and histo-

pathology demonstrated atypical cells. The patient was unable

to continue the UV treatment because of photo-induced inflam-

mation of the skin. Lesions that persisted without enlargement

during UV-B treatment were categorized as ‘‘active’’, and those

that resolved with treatment were categorized as ‘‘healed’’; this

categorization follows that reported by Vakeva et al.2 Regarding

the outcome, the group of patients with active disease (median

Correspondence: Rie Arai, M.D., M.P.H., Department of Dermatology

551-0032, Japan. Email: arai88@gaia.eonet.ne.jp

� 2011 Japanese Dermatological Association

history of disease 1.75 years, range 0.1–30 years) had a longer

disease course than the healed group (median history of disease

0.5 years, range 0.1–2 years). Most of the patients with active

disease had LPP (72.2% [13 ⁄ 18]) as well atypical cells (61.1%

[11 ⁄ 18]). The one patient with disease progression also had LPP

and atypical cells. The buttock was more frequently involved in

patients with active disease (55.6% [10 ⁄ 18]) than in the healed

group (20% [1 ⁄ 5]). All patients in the healed group had recei-

ved broadband UV-B phototherapy. The median duration of

, Osaka Saiseikai Izuo Hospital, 3-4-5 Kitamura, Taisho-ku, Osaka

1

R. Arai and Y. Horiguchi

phototherapy in the healed group (3.5 years) was longer than that

in the active group (2 years), but the difference was not significant.

All patients in the healed group had received broadband UV-B

phototherapy. It was also noted that the median duration of photo-

therapy in the healed patients was longer than that in the group

showing active disease. These findings suggest that disease remis-

sion requires sufficient phototherapy. Notably, the case that devel-

oped MF had not continued with phototherapy because of photo-

induced inflammation.

The effect of oral psoralen and UV-A (PUVA) phototherapy on

parapsoriasis may be better than UV-B phototherapy. However, we

are unable to obtain psoralen tablets for systemic PUVA photothera-

py in Japan. Considering the greater risk of side-effects including

carcinogenicity of PUVA compared with UV-B, it is important to

study the therapeutic effect of broadband or narrowband UV-B

phototherapy for this condition. Unfortunately, our study could not

certify the effect of narrowband UV-B phototherapy for parapsoria-

sis because the device had only been recently introduced at our

clinic. Considering that epidermal turnover time is approximately

1 month, our schedule of maintenance phototherapy was once or

twice a month. It has been reported that lesions of parapsoriasis

relapsed when phototherapy was discontinued.4 Although photo-

therapy is important for the treatment of parapsoriasis and MF,

there is still a lack of consensus regarding the frequency of mainte-

nance therapy.5

A previous study indicated that 10% (7 ⁄ 69) of patients with

SPP and 35% (12 ⁄ 36) of patients with LPP developed histologi-

cally confirmed MF within a median of 10 and 6 years, respec-

tively.2 In our study, the progression of parapsoriasis into MF

occurred only in the LPP group. This finding is consistent with a

previous study showing that LPP is prone to progress to MF.

2

Most of the initial skin lesions developed on the buttock and other

sun-protected areas in this study. It has been reported that atypi-

cal cells in the infiltrate tended to be found in lesions on the waist

or trunk.1 Cases showing lesions of parapsoriasis en plaques on

the buttock and other sun-protected areas may require more

careful follow up.

We suggest that long-term phototherapy has clinical benefits for

patients with parapsoriasis en plaques and that careful observation

is needed for patients with LPP, especially those with lesions on the

buttock area.

Rie ARAI, Yuji HORIGUCHIDepartment of Dermatology,

Osaka Red Cross Hospital, Osaka, Japan

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2 Vakeva L, Sarna S, Vaalasti A, Pukkala E, Kariniemi AL, Ranki A. A retro-

spective study of the probability of the evolution of parapsoriasis en

plaques into mycosis fungoides. Acta Derm Venereol 2005; 85: 318–323.

3 Belousova IE, Vanecek T, Samtsov AV, Michal M, Kazakov DV. A patient

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small plaque parapsoriasis and early-stage mycosis fungoides. ArchDermatol 1999; 135: 1377–1380.

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survey and literature review. J Am Acad Dermatol 2009; 60: 39–50.

� 2011 Japanese Dermatological Association