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mycosis fungoides palmaris et plantaris ( mfpp ) is an uncommon variant of mycosis fungoides ( mf ) limited to the palms and soles , first described by resnik et al . in 1995 .
since only 10 english papers about mfpp have been previously published , little is known about its pathogenesis . in this report
, we describe a case of mfpp showing a dense deposition of periostin ( postn ) in the cancer stroma , which might modulate the tumor microenvi ronment through tumor - associated macrophages ( tams ) .
our present case might suggest one of the possible reasons for the good prognosis of mfpp .
an 85-year - old japanese man visited our outpatient clinic with a 2-year history of pruritic erythema on his scalp .
his condition had been treated in a private clinic as pustulosis palmaris et plantaris with topical steroid and maxacalcitol , but they were ineffective . on his initial visit ,
physical examination revealed erosive , atrophic , well - demarcated scaly erythema on his right palm and right sole ( fig .
a biopsy specimen showed atypical large lymphocytes densely infiltrated mainly in the upper dermis with involvement of the overlying epidermis ( fig .
immunohistochemical ( ihc ) staining revealed that these atypical lymphocytes , which were distributed from the upper layer of the stratum spinosum to the dermis , were positive for cd3 , cd4 and cd5 , and negative for cd7 and cd8 . a full blood count and biochemical profile revealed eosinophilia ( 19.7% ) , and a significantly high level of serum il-2 receptor ( 925 u / ml ) .
we screened for possible metastatic lesions with positron emission tomography and computed tomography but found no evidence of metastasis . from the above findings , we diagnosed this patient as having mfpp .
we administered radiation therapy 40 gy in 20 fractions to the right palm and sole , and the erosive , atrophic erythema then disappeared .
to further investigate the possible immunological background of the mfpp , we employed ihc staining for postn , cd163 and cd206 .
ihc staining revealed the dense deposition of postn within the superficial to deep dermis ( fig .
mfpp is a rare variant of mf limited to the palms and soles [ 2 , 4 , 5 ] . since only a small number of cases
have been reported in english , the pathogenesis and biological behaviors of mfpp are still incompletely understood . among the published reports , nakai et al .  
reviewed 24 cases of mfpp , which suggested that patients with mfpp present a relatively good prognosis , and that radiotherapy is one of the best therapies for mpff .
excimer laser therapy ( 308 nm ) and bexarotene are also effective [ 4 , 5 ] and , to our knowledge , no patients have died from disease progression .
postn is an extracellular matrix protein that modulates the production of a series of chemokines from macrophages and fibroblasts [ 3 , 6 ] . as we previously reported , the deposition of postn is prominent in early stage ( patch to plaque stage ) of conventional mf .
in addition , previous reports also suggested that in vitro stimulation of monocyte - derived macrophages by postn induces the production of chemokines such as cxcl5 and cxcl10 , which correlates with the tumor - formation of mf in the early stage . in another report , zhou et al .   reported that postn secreted from glioblastoma stem cells increases the m2 tams in the tumor site , resulting in the growth of glioblastoma multiformes .
these reports suggest that the postn / tam axis might contribute to the progression of the early stage of mf . in our present case , unlike conventional mf in the tumor stage , the dense infiltration of atypical lymphoid cells as well as dense deposition of postn were observed throughout the dermis . in addition , the main population of tams was cd163cd206 macrophages , which suggested that tams were not polarized to m2 macrophages in mfpp . as a previous reports suggested ,
m2 macrophages produce ccl17 and ccl22 [ 9 , 10 , 11 ] , which recruit regulatory t cells ( tregs ) in the tumor microenvironment .
since a large population of tregs is associated with a poor prognosis in various types of human cancer , and the depletion of m2-like tams delays the cutaneous t - cell lymphoma development in vivo , the inhibition of m2 polarization in tams might be connected with the progression of mf .
concerning our present case , the phenotypes of tams were not polarized to the m2 phenotype , which might be responsible for the good prognosis in mfpp . since this report presented a single case of mfpp , and since we did not directly prove the relationships between immunomodulatory effects of postn and prognosis of mfpp , further analysis of the mechanisms underlying this phenomenon may provide fundamental insights into the mechanisms of postn with mfpp .
mycosis fungoides palmaris et plantaris ( mfpp ) is a rare variant of mycosis fungoides limited to the palms and soles . 
 although little is known about the pathogenesis of mfpp , this variant of mycosis fungoides presents a relatively good prognosis . in this report 
 , we describe an 85-year - old japanese man with mfpp . 
 immunohistochemical staining revealed the dense deposition of periostin in the cancer stroma , as well as infiltration of cd163+cd206 tumor - associated macrophages ( tams ) , which suggested the phenotypes of tams were not polarized to the m2 phenotype in the lesional skin of mfpp . 
 our present case might suggest one of the possible reasons for the good prognosis of mfpp .