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Paper text:
nearly half of pg cases are associated with underlying diseases and conditions such as rheumatoid arthritis , inflammatory bowel disease and a broad spectrum of hematologic disorders .
several substances including medications , substances of abuse and cosmetics have been reported to trigger pg through either systemic use or local injection .
in contrast to the long - held ancient belief that hirudotherapy can purify the body from almost any ailment , medicinal leech is most commonly used in the treatment of venous congestion after reconstructive surgery in contemporary medicine . hereby , we present a case of unjustified leech therapy for ulcerative colitis triggering several pg lesions at leech bite sites . 


 a 22-year - old woman with a 3-year history of ulcerative colitis was admitted to the hospital because of painful skin ulcerations on her legs ( figure 1 a - c ) .
she had nt been taking the treatment prescribed for her ulcerative colitis and had been lost to follow - up since diagnosis .
a few days before admission she received a single treatment of 4 to 6 locally applied leeches on her legs .
after the leeches dropped from her extremities , there were some itchy areas on the leech - adhered parts of her legs . on the third day after leech therapy
, she presented to the emergency department with several painful skin lesions on her legs . 
 
( a - c ) painful skin ulcerations with purple border 
 tissue cultures of the ulcerative skin lesion for bacteria , fungi and atypical mycobacteria were negative .
histopathological examination of a specimen from ulcer showed perivascular infiltrate of neutrophils and few lymphocytes in superficial and deep dermis , which confirmed the diagnosis of pyoderma gangrenosum .
abnormal results of laboratory tests included a hematocrit level of 16.2% , crp of 120 mg / l and erythrocyte sediment rate ( esr ) of 70 mm / hr . although she denied any history of bloody diarrhea or other symptoms of uc , colonoscopy showed diffuse ulceration with exudate and spontaneous bleeding along the rectal mucosa ( figure 2 ) . due to active ulcerative mucosa ,
sulfasalazine enema ( 1 g / day ) and prednisolone ( 30 mg / day ) were prescribed .
the skin lesions were considerably healed 6 weeks after commencement of treatment ( figure 3 a - c ) . 
  diffuse ulceration with exudate and spontaneous bleeding along the rectal mucosa ( a - c ) healing of skin lesions following treatment

 pyoderma gangrenosum ( pg ) is a rare non - infectious neutrophil - predominant inflammation of the skin that most commonly begins as a papule , nodule , vesicle or pustule on the lower extremities and rapidly progresses to a very painful purulent ulcer with a purple undermined border .
pg may also cause bullous or vegetative lesions and it may also involve peristomal , genital or extracutaneous sites .
systemic manifestations including fever , malaise , arthralgia , and myalgia may or may not accompany the skin lesions . 
 
 in approximately 50% of patients with pyoderma gangrenosum , an underlying systemic disease is found .
the most frequent systemic associations of pg are inflammatory bowel diseases , inflammatory arthropathies and hematologic disorders .
case reports of numerous other potential triggers and associations for pg exist : substances ranging from several medications , substances of abuse to tattoo dye and diseases ranging from rheumatologic disorders to major depression .
the exact pathogenesis of pg remains to be elucidated but the frequency of its association with autoimmune disorders suggests an immunological aberrancy at the heart of its pathogenesis .
the immunological theory is supported by several studies demonstrating various abnormalities in the immune cells of pg patients and helps explain certain clinical behaviors of pg including pathergy ( development of pg lesions at the site of minor skin trauma ) , peristomal development and favorable response to immunosuppressive drugs . 
 

this case deserves attention because the ancient use of medicinal leech has been resurrected in the last century ( including an fda approval in 2004 ) with modern research revealing several potentially beneficial bioactive substances in its saliva .
modern medicine has found use for leech therapy in a wide array of diseases and conditions such as cvd , reconstructive and microsurgery , malignancy , dm , infectious diseases , hearing abnormalities , arthritis and musculoskeletal pain . 
 

medical literature have reported post - leeching complications such as infections , local hypersensitivity reactions including itching , blister formation , necrotic ulcers and even local tissue damage ( flap death ) , blood loss because of prolonged hemorrhage and scars left by impaired healing of leech bites .
however there is no report of pyoderma gangrenosum triggering by leech in the literature . 
 

we report the first case to our knowledge where leech therapy triggered pg in a susceptible patient .
this could be a case of pathergy phenomenon , which is well recognized in up to 50% of patients with pg , but since our patient did not develop any reactions at other sites of skin trauma including her iv access sites and the skin biopsy did not exacerbate her existing lesion , the mere trauma of leech bite could not sufficiently explain her skin reaction .
allergic reactions have been reported as an uncommon precipitant of pathergy phenomenon . a local hypersensitivity reaction to leech saliva
could have induced the pg lesions in our patient . 
 
 as ancient medicine has been popularized in the recent decades in many nations , the unusual complications such as triggering pyoderma gangrenosum
should be considered in mind and searched appropriately in the evaluation of our patients . 


 we thank the patient for allowing us to discuss her case in this article .
pyoderma gangrenosum ( pg ) is a painful skin lesion that results from excessive inflammatory response to a host of traumatic , inflammatory , or neoplastic processes in susceptible individuals . 
 a clear pathogenetic mechanism as well as an exhaustive list of potential triggers for pg is yet to be fully characterized . 

 
 this case documents the occurrence of pyoderma gangrenosum following leech - therapy in a patient who is a known case of ulcerative colitis and it deserves attention because leeches have been part of medical armamentarium since ancient times and have re - emerged in the last century relying on their ancient charm and modern research revealing potential benefits of several bioactive substances in their saliva .