dapsone , 4 - 4-diaminodiphenyl - sulfone ( dds ) , was synthesized over a century ago and still continues to be used as a treatment option in many skin diseases including leprosy , dermatitis herpetiformis , acne , bullous pemphigoid , pyoderma gangrenosum , recurrent erythema multiforme , and urticaria . other adverse effects occurring infrequently include vomiting , anorexia , headache , hepatitis , insomnia , psychosis , tachycardia , and hypoalbuminuria . livedo reticularis is a complex clinical syndrome caused by changes in the blood flow of skin vasculature . this condition demands a detailed and meticulous etiological investigation since it can result from a wide variety of conditions including certain drugs . we report a case of a female patient who developed livedo reticularis during her therapy with dapsone for chronic urticaria . a 45-year - old normotensive and non - diabetic female presented with chronic urticaria of seven months duration . she was prescribed a fixed dose combination of montelukast 10 mg and levocetirizine 5 mg on a daily basis , and iv hydrocortisone 100 mg and i m pheniramine maleate 45 mg on an as and when required basis . one week later , the patient was given first dose of autologous serum therapy ( ast ) . the day patient received third dose of ast , she was also prescribed tablet dapsone 100 mg once a day as three days earlier she had an episode of urticaria . two weeks after starting dapsone , she developed a lace - like reddish rash all over her body particularly on the inner surface of upper and lower limbs , abdomen , and trunk [ figure 1 ] . the patient did not give any history of recent surgery , abortions or similar cases in family or complain of any joint symptoms , fever , and thrombotic episodes . complete blood count ( cbc ) , coagulogram , erythrocyte sedimentation rate ( esr ) , thyroid function tests ( tft ) , kidney function test ( kft ) , serum calcium , serum c3 , c4 , cryoglobulin , antinuclear antibodies , rheumatoid factor , serologies for hepatitis b and c , and urine analysis were reported to be normal . a diagnosis of livedo reticularis was made , and skin biopsy from left thigh region was sent for histopathological examination , which revealed hyperkeratosis of epidermis and mild perivascular collections of chronic inflammatory cell infiltrate along with a few eosinophils in subjacent dermis without thrombi [ figure 2 ] . ( a ) reticular reddish mottling of the skin of abdomen of the patient ( b ) reddish mottling of the skin of trunk of the patient histopathological examination showing hyperkeratosis of epidermis and mild perivascular collections of chronic inflammatory cell infiltrate along with a few eosinophils in subjacent dermis patient was asked to come for follow up every week . the rash persisted for first month and then resolved gradually over the period of next three months . livedo reticularis is a reticular red - violaceous mottling of the skin that appears usually on legs but may be generalized . it occurs due to reduction or interruption of the blood flowing through dermal vessels of skin . blood is supplied to skin in cones with 1 - 4-cm base located on the skin surface . each cone is fed by an arteriole , and it is this arteriole that is affected in the livedo , causing a mottled reticular pattern . livedo reticularis may be physiological ( due to cold ) , idiopathic , or secondary to many causes , for example , intravascular obstruction , drugs , arteritis , and infections . the evaluation of a case of livedo reticularis involves detailed history , physical examination , and laboratory tests along with histopathological examination , which may aid in identifying the underlying cause . in patients with secondary livedo reticularis or livedo racemosa , addressing the approximate cause amantadine as a causal agent for livedo reticularis is well known with other drugs like bismuth , pentazocine , non - steroidal anti - inflammatory drugs , and minocycline also implicated . amantadine - induced livedo reticularis was first described by shealy et al . in 1970 , occurring in 2 - 28% of patients , with most of them being females . livedo reticularis following amantadine usually appears weeks after initiation of therapy ; its etiology is not entirely understood , but it is believed to be due to the depletion of catecholamines at the peripheral nerve terminals . dapsone , one of the oldest antibacterial agents , continues to treat a range of dermatologic disorders characterized by abnormal neutrophil and eosinophil accumulation . it has been reported to affect other cellular processes that occur in eukaryotic cells , such as inflammation , migration , and apoptosis . in our patient , the condition appeared two weeks after dapsone therapy was started suggesting a temporal relationship . during this time , changes leading to development of livedo reticularis might have been in progress ; for instance , depletion of neurotransmitters or development of antibodies . punch biopsy of the lesion was inconclusive ; livedo reticularis is an occlusive condition rather than inflammatory one . we could not find any case of livedo reticularis with dapsone in pubmed or vigiflow database , while eight such cases have been reported to ehealthme.com till our last search . this reaction was reported by sher - i - kashmir institute of medical sciences ( skims ) , srinagar via indian pharmacopoeia commission - national coordinating centre ( ipc - ncc ) , pharmacovigilance programme of india ( pvpi ) on vigiflow . a causality category of  probable  using the naranjo scale was assigned to this adverse event . in view of the widespread use of dapsone , it was important to draw the attention of clinicians and dermatologists to this possible and rare adverse cutaneous reaction of dapsone .
dapsone is a drug commonly used in the treatment of various dermatological diseases . here , we report the case of a 45-year - old female prescribed dapsone for chronic urticaria after which she developed extensive livedo reticularis in the limbs , abdomen , and trunk . 
 the use of dapsone may be associated with a plethora of adverse effects including rash but livedo reticularis has been very rarely reported . 
 emphasis should be laid on the possible drug etiology in any patient who develops new signs and symptoms while on medications , even if it may not be supported by enough literature .