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Paper text:
kaposi sarcoma ( ks ) was described in 1872 as a neoplasm originated from vascular and lymphatic endothelia . since then
, four types have been described : classic , iatrogenic , endemic ( african ) and epidemic ( aids related ) .
human herpes virus 8 is often detected in all types of ks lesions which clinically can be seen as a violaceous patch , plaque or nodule . since the introduction of the combined antiretroviral therapy ( carv ) , the incidence of epidemic sk has dropped from 35% to only 3% , as reported in developed countries .
however , it is still a common finding among recently diagnosed aids patients and remains the most common type of sk seen in clinical practice . on the other hand , lichenoid keratosis
( lk ) , or benign lichenoid keratosis also known as lichen planus - like keratosis ( lplk ) , is a common lesion frequently seen as a single papule on the chest or upper extremities , more common in fair skinned women between 50 and 60 years - old .
its size varies between 3 and 10 mm , of light pink color , or intensely violaceous .
it usually is a single lesion , and only 8% present two and less than 1% present three lesions .
although initially described in 1966 as an incomplete or frustrated form of lichen planus , several clinical differences have made it a separate entity .
it has been suggested that lk may be the inflammatory stage of regressing solar lentigines or reticulated seborrheic keratosis , and possibly related to uv exposure .
some cases present spontaneous resolution although the usual treatment includes cryotherapy , curettage , electrosurgery and/or shaving .
we present the case of a 54-year - old male , diagnosed with hiv in 2002 , under carv therapy since february 2003 with emtricitavine , tenofovir and efavirenz .
he attended the dermatology office in january 2013 for presenting a 2-year evolution unique violaceous plaque on the right shin , oval shaped , that measured 2.5  3 cm , well demarcated and elevated , with some scale in the surface [ figure 1 ] .
violaceous patch on the right shin at the time of consultation , the cd4 lymphocyte cell count was of 491 and the viral load undetectable .
histopathology of the lichen planus - like keratosis with the inflammatory band infiltrate ( h and e 20 ) he received successful treatment with cryotherapy .
ks is an aids - defining clinical condition , and as such , a very strong association between ks and immunosuppression has been documented , further supported by the results that carv has diminished the ks incidence .
several reports have noted ks regression after successful response to antiretroviral therapy with increases in cd4 lymphocyte counts and undetectable viral load .
sk can manifest in patients receiving carv with undetectable viral load and high cd4 lymphocyte cell count .
as lplk is a common and benign lesion , scarce recent articles are written about it .
the importance of the correct diagnosis resides on the clinical differential diagnosis , which is primarily with malignant lesions of melanocytic origin or basal cell carcinoma , so one should keep this diagnosis in mind
. the histopathological differential diagnosis should be with lichen planus , lichenoid drug eruption , lichenoid acral lupus erythematosus , lichenoid graft - versus - host disease , inflamed seborrheic keratosis , halo nevus and lichenoid regression of melanoma .
fortunately for our patient , the biopsy reported a benign and localized non - hiv - related dermatosis , but cases like this teach us that although the clinical picture may be compatible with ks , we must still perform a skin biopsy which will clarify the diagnosis and determine which further studies and treatment should be done , if necessary . even if the patient is under good control for the hiv infection .
endemic sk continues to be a common finding even with high cd4 cell counts and undetectable viral load .
epidemic kaposi sarcoma is a common finding among hiv / aids patients that are not under antiretroviral treatment , and sometimes it is the first sign of the disease . 
 however , it can be seen even in patients with undetectable viral load and high cd 4 cell count . under these circumstances , 
 the clinical presentation can be atypical in location or number . 
 for this reason , the number of differential diagnosis is increased and biopsy of the suspicious lesions is essential for an accurate diagnosis and further apropiate treatment .