Blood, Vol. 95 No. 11 (June 1), 2000:
pp. 3635-3636
CORRESPONDENCE
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To the Editor: |
Variable course of patients with plaque psoriasis: lack of
transformation into tumorous mycosis fungoides
The question of whether plaque psoriasis (PP) must be
assessed as a premalignant state of mycosis fungoides (MF) is
still a matter of intense controversy.1-3 Muche et
al4 pointed the way, reporting that clonal T cells have
been found in high percentages in the blood of patients with small
plaque psoriasis (SPP), indicating the potential of malignant
transformation of this disease into T-cell lymphoma, whereas there were
no T-cell clones found in the blood of controls with contact
dermatitis. But in the skin of patients with SPP, no
T-cell clones were detected, and Muche et al suggested that
the clinical and histologic findings in SPP might be a successful
antitumor response to cutaneous T-cell lymphoma (CTCL). Our own
clinical and histopathologic data strongly support Muche et al's view.
In our study, 30 patients (29 males, 1 female)
diagnosed with PP had been admitted to the university`s
dermatology department in Munich from 1962 to 1985. We were able to
follow them up for a long time period. The observation time was 1 to 5 years for 13 patients, 6 to 10 years for 8 patients, and more than 10 years for 9 patients; the maximum observation period was 23 years.
The clinical type of PP was classified according to Bonvalet
et al.5 No patient in our study group suffered from
poikilodermatous PP. Bonvalet's classification was extended to the
mixed type of plaque psoriasis (MTPP) for those patients
with different types of plaques and for those who changed
from one type to another during the period of observation. The
different types of PP and their age-related distribution are listed in
the Table.
Some of the patients improved during the observation
period, but none of them showed complete clearing of all skin
lesions. PP is not a static disease but is characterized by a rather
dynamic clinical course. In only 12 of 30 cases was the diagnosis
maintained throughout the observation period. Different types of
eczema were discussed in 8 patients. In 12 patients a manifest MF was
diagnosed and histopathologically confirmed, and in 5 patients a
transformation into MF was considered.
Altogether 56 histopathologic specimens were taken from the 30 patients at the beginning of the disease and/or during its course. The histopathologic criteria were grading of the
exocytosis, density of the dermal infiltration, the presence of
microabscesses, and the extent of spongiosis present in the epidermis.
In 18 specimens taken during the course of the disease, the
diagnosis of PP has been dropped in favor of eczema. Transformation
into MF has been found in 4 specimens, and a manifest MF was diagnosed
histologically in 14 specimens. But none of the patients who had been
observed for at least 5 years developed the clinical findings of
terminal, tumorous MF or died from this disease.
Our findings indicate that PP often shows a changing feature
during its course of disease both clinically and histopathologically. None of the patients developed terminal MF, but the fact that in more
than 30% of the patients the diagnosis of MF was made at least once
during the course of PP and that in 17% a transformation into MF was
considered clearly indicates the problems in arriving at a definite
assessment of PP for nearly 1 century, because it was described for the
first time about 100 years ago. The investigator's uncertainty cannot be the only explanation; the histological specimens often do show signs that are typical for MF in the infiltrative state,
such as microabscesses or exocytosis.
Our study was based on a close clinical and
immunohistochemical follow-up, and no studies on clonal rearrangements
were performed with these patients. But modern
technologies such as polymerase chain reaction that locate
clonal cell populations provide greater opportunity for distinguishing malignant changes from
benign ones in the skin and blood when CTCL is suspected. Although
transformation to MF seemed to be present in a large number of our
patients, none of them developed the terminal stage of MF. That would
indicate in patients with PP the presence of a very strong factor with the ability to fight lymphoma. A similar possibility was
discussed by Muche et al. Identification of this
antitumorous factor would be one of the most interesting
discoveries that could be achieved in CTCL research.
Silke Stachowitz
Martin Mempel
Christian Schmöckel
Rita von Spanyi
Dietrich Abeck
Department of Dermatology and Allergy Biederstein
Technical
University
Munich, Germany
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References |
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Les differents formes du parapsoriasis on plaques: a propos de 90 cas.
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