INTRODUCTION:Lichen planus pigmentosus (LPP) was first described by Bhutani et al.1 The lesions are small, brown, oval macules with diffuse borders. Later, they merge to form pigmented areas which are grey or brown. The pigmentation may be diffuse, reticulate, blotchy, or perifollicular. The patches are usually symmetrical in distribution but may be found in a segmental, zosteriform, or blaschkoid pattern.2 CASE REPORT:A 21 year old male, waiter by occupation, hailing from Assam presented to the dermatology OPD with complaints of asymptomatic black discoloration mainly over back, neck, arms, thighs since 4 monthsPatient first noticed brown to black asymptomatic lesion over upper left scapular region which gradually spread to involve the entire back, abdomen, bilateral shoulders, lateral aspect of upper arm, buttocks, thighs and lower legs.There was history of application of mustard oil all over body everyday in the night since 3 years of age. Patient denies any history of long duration of sun exposure or outdoor activities as the lesions were mainly present over the sun protected areas sparing the sun exposed areas and flexural folds.On examination multiple ill defined diffuse hyperpigmentation tending towards symmetry over back, bilateral shoulders, arms, buttocks, thighs and knees was seen. (Figure a-f)There was complete sparing of face, intertriginous areas, forearm, legs, hands, feet , nails , oral and genital mucosa.Histopathological examination shows sparse superficial perivascular lymphocytic infiltrate with numerous melanophages within the papillary dermis. The papillary dermis is slightly thickened and shows delicate fibroplasia and mucin. Overlying epidermis shows focal vacuolar change in the basal layer and infiltration of interface by lymphocytes. The epidermis is flattened at places. The findings were suggestive of Lichen Planus Pigmentosus.(Figure: g-h)