a 23-year - old female presented with an asymptomatic , erythematous , atrophic macule on the upper right side of her back that increased gradually in size within the last four years without any symptoms ( figure 1a ) . on physical examination the surface of the lesion was smooth and no induration was examined on palpation .
dermatoscopic evaluation of the lesion using 3gen dermlite - ii pro hr and documented with dermlite - foto 3gen ( llc , dana point , ca , usa ) showed a homogenous pigment network on a purplish erythematous background ( figure 1b ) .
histopathological examination of h&e ( hematoxylin and eosin ) stained sections revealed epidermal atrophy , increase in melanin in basal keratinocytes and heavy dermal cellular infiltrate composed of spindle - shaped cells arranged in a storiform pattern that extended into the subcutaneous tissue ( figure 2 ) .
immunhistochemical staining for cd34 was positive , while factor xiiia was negative ( figure 3a , b ) .
dfsp is a rare , slow growing , locally invasive cutaneous neoplasm of fibrohistiocytic origin with intermediate grade malignancy with an incidence between 0.85.0 cases per 1 million persons per year .
the atrophic presentation of dfsp is the rarest variant of this infrequent neoplasm , which was first described in 1985 .
the non - protuberant dfsp can be considered the early clinical stage of dfsp before developing the typical protuberant feature unless it remains as a non - protuberant tumor that is called atrophic dfsp .
it occurs as an atrophic , asymptomatic plaque that can be difficult to distinguish from morphea , morphea like basal cell carcinoma , scar , lipoatrophy and atrophic dermatofibroma .
although the clinical appearance of atrophic dfsp is different from common protuberant type , histopathological features are similar .
atrophic presentation of the lesions may be due to the marked cellularity of the tumor cells in the dermis and infiltration to the subcutaneous fat .
immunhistochemical staining is important to distinguish dfsp from atrophic dermatofibroma and medallion - like dermal dendrocyte hamartoma .
while dfsp cells are positive for cd34 and negative for factor xiiia , atrophic dermatofibroma cells are usually negative for cd34 and both of cd34 and factor xiiia are positive in the medallion - like dermal dendrocyte hamartoma [ 3 , 4 ] .
dermatoscopic studies of dfsp are very rare in the literature . in 2013 , bernard et al reported the first study of dermatoscopic analysis of dfsp in 15 cases .
delicate pigment network , vessels , structureless light brown areas , shiny white streaks , pink background coloration and structureless hypopigmented or depigmented areas were defined as six main dermatoscopic features of dfsp . in 2014 , dermatoscopic features such as peripheral dilated vessels forming a mesh - like pattern , milky - red areas , whitish linear structures and fine pigment network were reported in a series of four cases of dfsp . to our knowledge , only one case of atrophic dfsp was presented with dermatoscopic features in the literature .
the reported dermatoscopic findings of that case were branching vessels on a yellowish background without pigment network .
the authors suggested that the dermatoscopic features might be the result of dermal atrophy and close approximation the subcutis to the epidermis .
in contrast , our case showed dermatoscopically regular brown lines reticular on a purplish erythematous background .
homogenous brown lines reticular seen in our case correspond to the accumulation of melanin in basal keratinocytes , while the erythematous background is the result of dilated vessels in the dermal plexus . here , the smooth surface reflects the stratum corneum being normal .
the most frequent dermatoscopic pattern associated with dermatofibromas , a well - known and benign cousin of dfsp , is the central white scar - like patch and peripheral delicate pigment network .
the histopathologic correlation of white scar - like patch in dermatofibroma is pronounced fibrosis within the papillary dermis .
contrary to dermatofibromas , fibroplasia in the upper half of the dermis is uncommonly observed in dfsp which may explain the absence of white scar - like areas in our case . in conclusion , we have presented the dermatoscopic findings in an unusual case of atrophic dfsp .
atrophic dfsp should be kept in the differential diagnosis for atrophic and depressed skin lesions , particularly those seen on the trunks of women .
dermatoscopy , a noninvasive method , may not only help to differentiate atrophic dfsp from other skin diseases but may also indicate the need for histopathological examination since the disease has prognostic significance .
 dermatofibrosarcoma protuberans ( dfsp ) is an uncommon locally aggressive mesenchymal tumor with a high local recurrence rate . 
 atrophic dfsp is a rare variant of dfsp characterized by a non - protuberant lesion . 
 we report on a 23-year - old female , who presented with an atrophic , asymptomatic macule on the right side of her back 2 cm in diameter . 
 dermatoscopic examination revealed homogenous pigment network on a purplish erythematous background . 
 the histopathological finding of the incisional biopsy material was consistent with dfsp . 
 to our knowledge , this is the second case of atrophic dfsp discussing the dermatoscopic features of this relatively rare condition . 