ashy dermatosis is a hypermelanotic disorder of the idiopathic variety characterized by bluish - grey macules in healthy individuals .
it is a controversial entity and is sometimes considered as a variant of lichen planus .
etiology of ashy dermatosis is mostly unknown and it usually affects the face , arms , neck , and trunk .
ashy dermatosis usually has a symmetrical distribution but cases with unilateral presentation have also been observed .
lichen planus pigmentosus , occupational dermatosis with hyperpigmentation , drug - related dermatoses , universal acquired melanosis , and familial progressive hyperpigmentation are the common entities confounding diagnosis .
our case was a 20 year - old indian male who presented with slowly progressive , diffuse darkening of the face , arms , neck , and trunk seen over the last two years [ figures 1 and 2 ] .
he had no previous history of skin diseases and was not on any kind of medication during this two - year period .
laboratory investigations suggested normal blood counts , blood glucose level , normal liver and kidney function test and normal acth stimulation ( sensitive ) test results .
bluish black discoloration of face , chest , and upper extrimity bluish black discoloration of neck and back oral mucous membrane and palate are not involved
 it has been a controversial topic that has showed a tendency to appear mostly in dark colored individuals and also in asians .
confusion also arises because the disease is also known by many different names like erythema dyschromicum perstans and lichen planus pigmentosus .
others have suggested that ashy dermatosis presents clear clinical characteristics but that histopathological findings are not specific .
our differential diagnoses revolved around lichen planus pigmentosus , occupational dermatosis with hyperpigmentation , drug - related dermatoses , universal acquired melanosis , allgrove 's syndrome , dermatomyositis , and familial progressive hyperpigmentation syndrome .
absence of occupational exposure ruled out occupational dermatosis with hyperpigmentation ; dermatomyositis is a condition of muscle weakness , and allgrove syndrome is characterized by alacrima , achalasia , and acth insensitivity .
but the patient did not show any of these symptoms and signs . a normal creatinine phosphokinase ( cpk ) level ruled out the chances of dermatomyositis , and a normal barium meal x - ray and acth sensitivity test ruled out allgrove syndrome .
the patient had not taken any drugs in this period.so drug - related dermatosis was ruled out .
the histopathological study was not conclusive enough to differentiate from lichen planus pigmentosus but the absence of pruritus , the lack of involvement of the oral mucosa , and the bluish - black discoloration in our patient , a dark colored indian in his second decade of life support our diagnosis in favor of ashy dermatosis of the idiopathic variety .
the only treatment in this condition resulting in considerable improvement in pigmentation is clofazimine at a dose of 100 mg three times per week for three to five months .
 we present here the case of a young indian male with slowly progressive , diffuse darkening of the face , arms , neck , and trunk . 
 the patient was not taking any medication and there was no history of any previous skin disease and the mucous membrane was not involved . 
 these findings are consistent with a diagnosis for ashy dermatosis of unknown etiology . 
Introduction
Case Report
Discussion